Immunological Aspects of Leprosy with Special Reference to Autoimmune Diseases 0

'Bull. Org. mond. Sante 1969, 41, 793-804 Bull. Wld Hlth Org.

Immunological Aspects of Leprosy with Special Reference to Autoimmune Diseases 0. WAGER1

Leprosy, particularly lepromatous leprosy, is associated with a multitude of (auto) immune aberrations, and its clinical features also have much in common with the collagen diseases. Immunopathological studies of the 2 groups of diseases may thus elucidate the basic mechanisms of both. The reported evidencefor a genetically determined hyporeactivity ofcell-mediated (CM) immunity in lepromatous subjects is reviewed; most, but not all, of the findings fit such a hypothesis well. The possibility remains that the observed hyporeactivities may be secondary to direct effects of Mycobacterium leprae. Evidencefor a general hyperreactivity of the antibody-mediated (AM) immunity in lepromatous leprosy is then reviewed and considered to be fragmentary. The concept and general criteria of autoimmunity are discussed briefly and the high incidence in lepromatous leprosy of various (auto)immune aberrations, resembling those in systemic lupus erythematosus (SLE) and in rheumatoid arthritis is reviewed. Although autoantibodies are not likely to be directly deleterious to the host, immune complexes containing autoantibodies may be pathogenic. Mixed cryoimmunoglobulins, consisting of 2 (IgG-IgM or IgG-IgA) or 3 immunoglo-. bulins, and occasionally also containing measurable amounts of complement components, have recently been encountered in SLE and its variants and also in a number of microbial diseases with autoimmune features (syphilis, streptococcal nephritis and endocarditis, mononucleosis, Mycoplasma pneumoniae pneumonia). They may represent circulating immune complexes, analogous to the IgM (IgA) rheumatoid factors in combination with their IgG reactants. In leprosy also, the existence of pathogenic immune complexes is indirectly suggested by mixed cryoglobulinemia andfurther by a number of other features reviewed in this article.

leprosy is an infectious disease associated with a The clinical features of leprosy also have much in multitude of immunological aberrations. Both the common with collagen diseases. In fact, as has been cell-mediated (CM, " thymus-dependent ") and the pointed out by Matthews & Trautman (1965), were antibody-mediated (AM, " bursa-dependent ") im- leprosy not present in patients with, for example, mune systems are involved (Oort & Turk, 1965; polyarthritis, subcutaneous nodules, lymphadeno- Parrott, de Sousa & East, 1966; Cooper, Gabriel & pathy, hepatosplenomegaly, butterfly facial lesions, Good, 1967). The responses fall predominantly etc., a collagen disease would immediately be sus- within the types III and IV of the widely used classi- pected on the basis of clinical findings. fication of allergic responses by Gell & Coombs The immunological aberrations in leprosy, with (1963) (see Annex). Many of the AM responses are the exception of the lepromin reactivity, have only similar to those regarded as typical of the so-called recently been subjected to more extensive analyses by collagen diseases, say, systemic lupus erythematosus modern immunological techniques. Similar aberra- (SLE) and rheumatoid 'arthritis. tions in collagen diseases, on the other hand, have for some decades already been studied intensively, and much valuable information has been collected I Assistant Professor of Serology and Bacteriology, Helsinki University, and Head of the Municipal Bacterio- on the underlying mechanisms and their pathogenic logical Laboratory, Aurora Hospital, Helsinki, Finland. role.

2434 - 793 - 4 794 0. WAGER

The etiology of the collagen diseases, however, closely to that seen in guinea-pigs treated with anti- remains unknown, whereas that of leprosy, with lymphocyte serum (Turk & Waters, 1968), i.e., a reasonable likelihood, is infection by Mycobacterium replacement of the lymphocytes in the paracortical leprae. Thus, the information extracted from immu- (thymus-dependent) area by reticulohistiocytes (Turk nological studies of leprosy, on one hand, and of the & Willoughby, 1967). The germinal centres and the collagen diseases on the other, might possibly be medullary cords (bursa-dependent area), however, mutually useful in elucidating the basic mechanisms were normal. of both. These findings all fit well the hypothesis of genetic- In the following report the main emphasis is laid ally determined general depression of the CM im- upon descriptions of the AM immune responses and munity (Turk, 1968 and personal communication; reference is made to analogies between the AM re- Newell, 1966). sponses in leprosy and in collagen disease. There are, however, other features in lepromatous leprosy not so compatible with such a hypothesis. First, the distribution of the incidence of tuberculin IMMUNE MECHANISMS positivity (Mantoux) in different age-groups of Cell-mediated immunity patients with lepromatous leprosy is the same, or only slightly lower, than that found in the general The lepromin reactivity of the Mitsuda type is population (Hart & Rees, 1967; Guinto & Mabalay, generally regarded as an example of delayed cell- 1962) 1 in spite ofthe common antigenic determinants mediated hypersensitivity to the bacillary component shared by Myco. leprae, Myco. tuberculosis and a of lepromin. To the arguments favouring this view, variety of other mycobacteria and Nocardia (Rees et as given recently in a comprehensive review by Hart al., 1965; Norlin et al., 1966; Estrada-Parra, Rojas- & Rees (1967), may now be added a claim of success- Espinosa & Reyes-Gomez, 1968; Navalkar, 1968). ful passive transfer of lepromin sensitivity by Secondly, in lepromatous leprosy, BCG-induced lymphoid cells from sensitized guinea-pigs to isolo- weak lepromin reactivity is 11 %-50 % in different gous recipients (Goihman-Yahr, Raffel & Ferraresi, studies, while converting normally to tuberculin 1968). reactivity (Hart & Rees, 1967). In addition to lepromin negativity, other phenom- Thirdly, CM immunity is generally believed to ena compatible with a depression of CM immunity play a central part in the resistance not only to have been observed in lepromatous leprosy. These mycobacterial infections (Lurie, 1964; Salvin, 1963), include the following: but also to fungal and viral infections and in resis- (1) impaired reactivity to unrelated skin test tance to tumours. Yet, tuberculosis is no more antigens, such as Candida albicans, 2, 4-dinitrochloro- common among patients with lepromatous leprosy benzene and picryl chloride (Buck & Hasenclever, than in the general population (Khoshoo, 1968), nor 1963; Guinto, 1968; Bullock, 1968; Waldorf et al., is malignancy (Oleinick, 1968) with the possible 1966). exception of tumours of the skin (Michalany, 1966). (2) Impaired lymphocyte transformation response The same seems to apply to the incidence of viral to phytohaemagglutinin, to Myco. leprae and Myco. infections. tuberculosis antigens (Dierks & Shepard, 1968), and Thus, the evidence so far produced for the attrac- to streptolysin,O (Sheagren et al., 1967), in cultures tive thesis of a genetically determined general from peripheral blood. depression of the CM immunity in lepromatous leprosy cannot yet be regarded as conclusive. The (3) Delay in the rejection of skin homografts up possibility remains that this depression may be secon- to a maximum of 70 days in 4 patients with lepro- dary to direct effects ofMyco. lepraeinfection (Guinto, matous leprosy grafted with skin from donors with a 1968), resulting, for instance, in specific tolerance similar type of disease (Job & Karat, personal com- of the CM system while the AM system remains munication, cited by Hart & Rees, 1967). (4) A higher than normal incidence of local I See also Bechelli, L. M. (1965) A review of present necrotic and disseminated reactions following small- literature on the immuno-allergic correlation between tuberculosis and leptosy; unpublished WHO working document pox vaccination (Turk, personal communication). PA/66.59. A limited number of copies of this document is A of available to persons officially or professionally interested on (5) histological picture lymph nodes from request to Leprosy, Division of Communicable Diseases, 9 patients with lepromatous leprosy, corresponding World Health Organization, 1211 Geneva, Switzerland. IMMUNOLOGICAL ASPECTS OF LEPROSY 795 specifically active. Burnet (1968) has recently sug- enhancing effect upon the agglutinin titres, as it is gested that such a state of split tolerance may be known to do in rheumatoid sera (Wager, 1950). caused in subacute sclerozing panencephalitis by in- The specificity of the elevated antistreptolysin-O fection of the thymus with the measles virus. titres, again, was not ascertained by removal of the Further research should include extension of the lipids known to cause non-specific increase of the most challenging histological studies of 9 lymph antistreptolysin titres in dysproteinaemic states, such nodes taken from patients with bacilliferous lepro- as hepatitis and liver cirrhosis. matous leprosy (Turk & Waters, 1968) to bacillus- And yet, taken together, these pieces of evidence free nodes from both polar ends of the spectrum, and constitute a mosaic, suggesting a possible general particularly to nodes from lepromin-negative subjects hyperreactivity of the AM immune responses. The without clinical leprosy and to the thymus gland. In presence of large amounts of mycobacterial adjuvant order to ascertain the inclusion of subjects genetically in the tissues of lepromatous patients, in fact, lacking the " N-factor " (Newell, 1966), a sufficiently would suffice to explain such a hyperreactivity large number of samples should be collected from without any additional hypothesis of a primary cons- adults living in heavily infected endemic areas. titutional host-dependent hyperreactive make-up of the lepromatous host. Antibody-mediated immunity More extensive and controlled vaccination trials In sharp contrast to the hyporeactive state of the with a variety of immunogens unrelated to Myco. CM immune responses in lepromatous leprosy, data leprae may throw more light upon these considera- compatible with a general hyperreactivity of the AM tions. immune responses in lepromatous leprosy have been In this context, it may be mentioned that a similar published. dissociation of the CM and the AM immune re- In addition to precipitating antibodies to a variety sponses has been observed in rheumatoid arthritis of mycobacterial antigens (Bullock, 1968; Rees et al., (Houba et al., 1964). 1965; Estrada-Parra, Rojas-Espinosa & Reyes- Gomez, 1968; Navalkar, 1968) found in the sera from Autoimmune serum factors lepromatous patients and in much lesser degree The concept of autoimmunity has become increas- in those from patients with tuberculoid leprosy, ingly difficult to define. The original term "auto- typhoid vaccination induced higher agglutinin titres immune disease" implies direct attack by immunologi- in lepromatous patients than in normal controls cal factors on the tissues towards which the immuno- (Almeida, Brandao & de Lima, 1964). The titre level logical factors are directed. However, in many condi- of isoagglutinins (Buck & Hasenclever, 1963), of tions, traditionally accepted as respectable members agglutinins against Candida albicans (Buck & of the family of autoimmune states, say, SLE Hasenclever, 1963), and the antistreptolysin-O titres nephritis, the tissue damage actually seems to be (Eliasberg, 1911) were also higher in non-vaccinated caused by antigen-antibody interactions unrelated to patients with lepromatous leprosy than in controls. the target tissue (see below). The role of the target Depressed level of haemolytic complement (Elias- tissue, so to speak, seems to be limited to that of an berg, 191 1; de Azevedo & Melo, 1966) and its innocent bystander caught up in an immunological components (Bonomo et al., 1967) have also been event not of its own making (Vaughan, 1965). reported to occur particularly in the reactional phases However, the term " autoimmunity " being widely of leprosy, and interpreted as indirect evidence for accepted, it does not seem wise to become hopelessly- complement-fixing antigen-antibody interactions in entangled in semantics, e.g., by suggesting replace- vivo. ment of this traditional term by others, such as auto- The evidence for a general hyperreactivity of the allergy, auto-aggression or autosensitivity. A better AM immune mechanisms, however, is rather frag- choice, according to the advice of Dixon (1967), is to mentary, and only too susceptible to criticism. As to concentrate upon the different basic, and possibly the effects of typhoid vaccination (Almeida, Brandao pathogenic, immune mechanisms operative within & de Lima, 1964), the lepromatous leprosy series and this fairly ill-defined group of diseases. the control series were not comparable as regards age. To this end, the classification of the allergic reac- The probable presence of the rheumatoid factor in tions into 4 types by Gell & Coombs (1963) is appli- many of the lepromatous leprosy sera (Bonomo & cable, and for practical diagnostic and therapeutic Dammacco, 1968), furthermore, may have exerted an purposes, the " markers of autoimmunity " as 796 0. WAGER

proposed by Mackay & Burnet (1963) have proved directly any major part in the pathogenesis of most useful. The two classifications, slightly modified, leprosy. are given in the Annex. As to those immunological mediator mechanisms, Leprosy, particularly its lepromatous type with possibly responsible for tissue lesions in leprosy, the erythema nodosum leprosum (ENL) reactions, meets experimental observations on the phlogogenic most of the requirements for autoimmunity as laid capacity of soluble antigen-antibody complexes and down by these markers. Its infectious etiology, the rapidly accumulating evidence that similar however, has excluded it from " full membership " mechanisms are operative in SLE nephritis are of in the family of autoimmune diseases sensu stricto. greatest interest, and will be dealt with below. Hypergammaglobulinaemia, for example, is a common finding in leprosy (Matthews & Trautman, Antigen-antibody complexes as a cause of tissue 1965; Bonomo & Dammacco, 1968; Bonomo, damage Dammacco & Gillardi, 1968). A high, SLE-like Experiments in animals have clearly established incidence of various autoantibodies or " autoim- that intermediate-sized antigen-antibody complexes mune serum factors" has been reported by several formed in moderate antigen excess and therefore authors to be a feature of lepromatous leprosy. soluble are able to cause tissue lesions that neither These observations have recently been discussed and antigen nor antibody alone causes, if administered summarized by Bonomo & Dammacco (1968), who separately (Dixon, 1962-63, 1965; Weigle, 1961). also made a comparison between the autoimmune Pathogenetically, the simplest complex-induced patterns in leprosy and SLE. The approximate lesion is the Arthus reaction, a localized, acute incidences in lepromatous leprosy (and SLE) were necrotizing vasculitis. The complexes, once deposited for antinuclear factors 30% (95 %), for LE-cells in vessel walls, via their reaction with complement, 8% (95 %), for rheumatoid factors 50% (70%), for attract polymorphonuclear leucocytes which, in turn, thyroglobulin antibodies 40% (20%), for cryoglo- release various enzymes injurious to vessel walls. In bulins 95% (50%), for biologically false positive the sites of tissue lesions, the antigen in question, host tests for syphilis 70 % (20 %), and for low complement immunoglobulin (probably the corresponding anti- levels 50% (50 %). Thus, a broad serological overlap body) and complement components can be shown by between SLE, the autoimmune diseasepar excellence, immunofluorescent methods. More complex, but and lepromatous leprosy has been clearly established, closer to the situation in systemic human disease, is and as to the incidence of the rheumatoid factor (RF), the classical " one-shot " serum sickness. also between lepromatous leprosy and rheumatoid Most applicable to systemic human disease, how- arthritis. An issue of greater importance than the ever, is the experimental antigen-antibody complex mere presence of the various autoimmune factors in nephritis, first induced by Dixon and his co-workers the circulation, however, is their possible role in the (Unanue & Dixon, 1967) in rabbits by intravenously pathogenesis of the leprosy lesions. injecting daily for prolonged periods small amounts Circulating autoantibodies in general do not seem of heterologous serum protein (BSA, HSA, BGG, to be directly deleterious to the host, with the notable HGG). In those rabbits making antibody responses exception of autoantibodies causing red cell destruc- too small to cause elimination ofantigen but sufficient tion in autoimmune haemolytic anaemia. In leprosy, to result in the formation of soluble antigen-antibody cold agglutinins against human 0 cells have not been complexes, a chronic progressive glomerulonephritis found (Matthews & Trautman, 1965). On the con- developed. Again, antigen, host gammaglobulin, trary, a protective role has been ascribed to some and host complement were found concentrated in the autoantibodies, e.g., the RF (Vaughan, 1959; Houba thickened glomerular basement membranes. By et al., 1964). The best example of a " physiologi- electron microscopy, a lumpy, dense deposit was cal ", non-aggressive autoantibody is the immuno- seen along the outer aspect of the basement mem- conglutinin, which fulfils all the criteria for an auto- brane. antibody against autologous altered complement, and During the last few years, evidence has been accu- yet with reasonable likelihood enhances the resis- mulating that analogous mechanisms are responsible tance, at least of mice, to a variety of bacterial infec- for the nephritis (Koffler et al., 1967; Christian, tions (Coombs, Coombs & Ingram, 1960). Hanauer & Pincus, 1967) and the skin lesions By analogy with what has been said above, the (Kunkel & Tan, 1964) in human SLE as well as for circulating autoantibodies are not likely to play the spontaneous lupus-like glomerulonephritis in IMMUNOLOGICAL ASPECTS OF LEPROSY 797

NZB and related strains of mice (bIixon, Edgington ditis. This method, however, is elaborate, insensitive & Lambert, 1967). and, in addition, it does not make certain the antigen- In addition to demonstrating gammaglobulin and antibody nature of the gammaglobulin complexes. complement components by immunofluorescence at The recent findings on cryoglobulinaemia, to be the sites of lesions, gammaglobulin-containing acid reviewed below, may have opened new possibilities eluates from the SLE kidneys and NZB mouse to attack these problems. kidneys contained high concentrations of antinuclear antibodies. Nuclear antigens deposited along the Cryoimmunoglobulins glomerular capillary walls also were detectable by Cryoglobulins, by definition, are serum globulins immunofluorescence (Dixon, Edgington & Lambert, precipitating in the cold (+4°C) and soluble at body 1967; Koffler et al., 1967). Furthermore, nuclearDNA temperatures (Lerner, Barnum & Watson, 1947). antigen was found in the serum of NZB mice by the Cryoimmunoglobulins most likely to represent Ouchterlony technique (Dixon, Edgington & Lam- circulating immune complexes are those composed bert, 1967), and in the serum of patients with SLE of 2 (IgG-IgM or IgG-IgA) or 3 (IgG-IgM-IgA) nephritis a replacement of antinuclear antibody by polyclonal immunoglobulins and occasionally also circulating nuclear antigen has been observed in containing measurable amounts of complement association with aggravation of this form of renal components, primarily C'3A (P,A). disease (Tan, Schur & Kunkel, 1965). Mixed (IgG-IgM and IgG-IgA) cryoglobulinaemia These findings suggest that the possibly pathogenic, has been recently encountered in association with complement-fixing immune complexes in human SLE, with its variants, such as the purpura-arth- SLE, and in the SLE-like nephritis in NZB mice, ralgia-Raynaud phenomenon-glomerulonephritis- are composed of nuclear antigens and the corres- rheumatoid factor syndrome, with rheumatoid ponding antibodies. arthritis, with polyarteritis nodosa and with other Other indirect pieces of evidence for the presence pathological conditions probably caused by under- of immune complexes (or other complement-fixing lying autoimmune (immune complex) mechanisms aggregates) in the circulation of patients with SLE (Hanauer & Christian, 1967; Meltzer & Franklin, are the depression of the C'3 component (P,iC-PiA 1966; Peetoom & Loghem, 1965; Wager, Mustakallio globulin) and of the total haemolytic complement & Rasanen, 1968; Wager et al., 1967; Wager & activity occurring during periods of clinical exacerba- Rasanen, 1969). tion, the presence in fresh plasma of altered com- The simultaneous occurrence of mixed cryoglo- plement component C'3A (flA), and the anticom- bulins and a number of recognized autoantibodies plementary activity of many SLE sera (Christian, (cold agglutinins, rheumatoid factors, antinuclear Hanauer & Pincus, 1967). antibodies) in syphilitic infections (Mustakallio, Recently, Penttinen and his co-workers have re- Lassus & Wager, 1967; Wager et al., 1967), post- ported most interesting observations on the capacity streptococcal nephritis (van Loghem, 1966), staphylo- of minute amounts of certain soluble viral antigen- coccal osteitis, subacute bacterial endocarditis and antibody complexes to aggregate platelets, and they Mycoplasma pneumoniae pneumonia (Wager, un- have produced evidence suggesting a pathogenic role published data), infectious mononucleosis and for rubella antigen-antibody complexes in the post- cytomegalovirus-mononucleosis (Wager et al., rubella thrombocytopenic purpura (Penttinen & 1968a), and in other diseases related to microbial Myllyla, 1968; Myllyla et al. 1969). From their infection, is interesting, considering a possible results, it appears possible that virus antigen-anti- causal relationship between infection on the one body interactions may be important also in other hand and autoimmunity on the other. manifestations and late complications of viral infec- Recently,Wager and his co-workers have isolated tions. and characterized 120 cryoglobulins composed of Attempts at direct identification and isolation of IgG and 1gM or IgA or both, out of which 19 also the immune complexes from human sera, however, contained PiA (Wager & Riisiinen, 1969). In addition have met with difficulties. Ultracentrifuge analyses, it to cryoimmunoglobulinaemia, other immunological is true, have yielded evidence for the presence of aberrations were encountered in the sera of these soluble immune complexes, e.g., in the sera frcm 120 patients. Cold agglutinins were found in 58% patients with SLE, purpura, rheumatoid arthritis, (normal incidence 21 %), rheumatoid factor activity Sjogren's syndrome, and subacute bacterial endocar- in 30% (4.1 %), and antinuclear antibodies in 35% 798 0. WAGER

(0.5%) of the cryoglobulinaemic sera. The various (2) The thermolabile anticomplementary effect of serological activities were recovered in several the isolated cryoglobulins. instances from the isolated cryoglobulins, and were (3) The presence of complement components in in some instances found in these only. Most of the the isolated cryoglobulins. isolated cryoglobulins, their parent sera and the serum supernatants left after removal of the cryo- (4) The various (auto)antibody-like activities of precipitate, possessed a strong anticomplementary the isolated cryoglobulins. activity, similar to that shown under the same (5) The presence of DNA in some of the cryo- experimental conditions by known specific precipi- globulins isolated from sera of patients with SLE tates of human and rabbit origin (Wager et al., 1967, (Forsen & Barnett, 1968). 1968a, 1968b; Wager, Mustakallio & Riisiinen, It seems possible that only a part of the circulating 1968). Heating at +56°C in most instances abolished immunocomplexes possess a cryoprecipitating pro- or greatly reduced the anticomplementary effect of perty as the various serological activities, including the cryoglobulins (and their parent sera), and prob- the anticomplementary activity of the whole sera, ably had some similar action upon the diphtheria mostly diminished only slightly or non-measurably toxoid-human IgG-IgM-IgA antitoxin precipitate, following removal of the cryoprecipitate. but it had no measurable effect upon the egg albumin- Assuming that the mixed cryoimmunoglobulins rabbit IgG antibody precipitate formed by Ea and represent complexes composed of "IgG-antigen " hyperimmune rabbit antiserum. Three human poly- and " IgM and/or IgA-antibody" components, clonal IgG preparations were not anticomplementary, 2 questions immediately arise. First, what is the but became slightly anticomplementary following primary event making the autologous IgG auto- treatment at +56°C and highly so when treated at antigenic? Second, are these immune complexes, all +63°C. Human IgA and IgM -preparations were or a part of which possess cryoprecipitating pro- not anticomplementary and were not affected by perties, pathogenic like those believed to be re- treatments at +56°C or +630C. sponsible for the lesions in the experimental nephritis The IgG-IgM cryoglobulins have been subjected and in SLE? to some dissociation and reprecipitation analyses As to the first question, the primary events might employing acid buffers and gel-filtration on Sephadex well be similar to those probably responsible for the G-200 (LoSpalluto et al., 1962; Peetoom & van elaboration of the rheumatoid factor, i.e., a sustained Loghem, 1965; Wager et al., 1967). Neither of the stimulation with some antigen or antigens, leading dissociated components possessed cryoprecipitating first to specific IgG antibody formation against the capacity alone, but reprecipitation in the cold oc- primary antigen or antigens and then, via antigen- curred when the components were brought together. IgG antibody complex formation to unfolding of The IgM component behaved as the "antibody " by the IgG molecule and exposure of hidden auto- accepting as its cryoprecipitating "antigen " any antigenic determinants on the latter. These exposed human (and even rabbit) IgG, whereas the IgG IgG-determinants would then secondarily induce the component for cryoprecipitation required the IgM elaboration of anti-IgG autoantibodies, usually of component of the cryoglobulin, and failed to cryo- the IgM variety (Christian, 1965). precipitate with IgM from other sources. The The primary inciting antigen then would likely be evidence, admittedly mainly circumstantial, for the the corresponding causative agent (treponeme, immune complex nature of the mixed cryoimmuno- streptococcus, cytomegalovirus) in infectious diseases, globulins may be summarized as follows: unknown in rheumatoid arthritis (perhaps myco- (I) The dissociation and reprecipitation patterns plasma or virus), and Myco. leprae antigens in of the IgG-IgM cryoglobulins resembling the be- leprosy. There is clinical as well as experimental haviour of the IgM rheumatoid factor (" anti-IgG evidence suggesting that mechanisms as delineated factor ") reacting with its human IgG "antigen " above may be responsible for the production of and cross-reacting with heterologous IgG (Aho, rheumatoid factors (Abruzzo & Christian, 1961; 1961). This analogy is further supported by'the pre- Aho et al., 1962; Aho & Wager, 1961) and also of sence in practically all of the mixed cryoimmuno- mixed cryoimmunoglobulins (Catsoulis, Franklin & globulins hitherto reported of IgG as one of the Rothschild, 1965; Wager & Raisanen, 1969). components, the other components being either IgM As to the second question, not much is actually or IgA or both. known about the pathogenicity of the cryoimmuno- IMMUNOLOGICAL ASPECTS OF LEPROSY 799 globulins proper. The most suggestive evidence is line defence " anti-IgG antibodies. The free antigen- indirect and comes from the clinical observations of IgG complexes, untrapped by the latter, would then the various manifestations of cold sensitivity asso- be the likely culprits causing tissue damage. ciated with the. purpura-arthralgia-Raynaud-rheu- To conclude, whatever the role of the mixed matoid factor syndrome. In skin biopsy specimens cryoimmunoglobulins may be in the pathogenesis taken from a few patients with this syndrome, of various diseases, they seem to offer a multitude of immunoglobulins (IgG and IgM) and complement possibilities for further studies, which may throw (PiA) have been found in the vessel walls by immuno- light upon the corresponding basic immunopatho- fluorescent methods, and histologically Arthus-like logical mechanisms. changes were seen (Miescher, Paronetto & Koffler, 1966). Nothing is known, however, of the possible Immune complexes in leprosy cryoprecipitating properties of these deposited The pathogenic significance of immune complexes immune complexes. composed of mycobacterial antigens and the cor- In most other conditions associated with cryo- responding antibodies, as a probable major cause of immunoglobulinaemia, the patients do not exhibit tissue lesions in leprosy has been emphasized par- any overt clinical signs of cold sensitivity (Wager ticularly by Almeida (1963a, 1963b, and personal et al., 1968a, 1968b). Intradermal injection of communication). autologous IgG-IgM cryoglobulin isolated from a Direct proof for the existence in leprosy of such patient with M. pneumoniae pneumonia and skin pathogenic immune mechanisms, however, is lacking. rash did not cause any immediate or delayed local The indirect evidence is only suggestive, inferior to reaction (Wager, unpublished data). that presented for analogous mechanisms in SLE There appears to be a considerable variation in (see above, pp. 796-797), and may be summarized the solubility patterns of individual cryoglobulins. as follows: Most of them were readily redissolved in vitro at +37°C, but some, primarily those isolated from (1) The initial local lesions of the ENL reaction is patients with the purpura-cold sensitivity syndrome, characterized by vasculitis and polymorphonuclear were only partially soluble at +37°C (Wager, leucocytic infiltration (Panel on Lepra Reaction, unpublished data). The same applies to the tem- 1963), resembling the Arthus reaction (Turk, 1968), perature and pH requirements for dissociation of the and the systemic pyrexial reactional phases with components, as shown by preparative procedures renal and joint involvement have common features (Wager, unpublished data) and also by analytical with serum sickness. ultracentrifugation of some cryoglobulins (LoSpal- (2) In reactional phases and following initiation luto et al., 1962; Wasastjerna et al., 1967). Thus, of sulfone treatment, fresh sera of patients with some cryoglobulins seem to be composed of more lepromatous leprosy exhibit high anticomplementary " avid " components than do others. The size of the activity, which is thermolabile (Almeida, 1963 and immune complexes, shown under experimental con- personal communication).' The haemolytic comple- ditions to be of paramount importance for their ment level (Eliasberg, 1911; Azevedo & Melo, 1966) localization in vascular structures (Cochrane, Haw- and the level of C'3A (P,A) is low (Bonomo et al., kins & Kniker, 1967), may be added to the list of 1967). factors probably determining the in vivo behaviour (3) Free or excess mycobacterial antigen has been of the cryoimmunoglobulins also. demonstrated in some leprosy sera (Rees et al., 1965) Finally there remains the possibility that the IgM and polysaccharides, possibly of mycobacterial or IgA components or both of the circulating cryo- origin, in reactional states (Silva & Tuma, 1960). globulins, by analogy with what has been said about the rheumatoid factors above (see above, pp. 795- (4) Leprosy sera caused sharp contractions of 796), are exponents of defence mechanisms of the host guinea-pig uterine horns under Schultz-Dale type against exogenous or endogenous antigens in com- experimental conditions. This property was heat- binations with their corresponding IgG antibody. labile and was inhibited by anti-histamines (Castro, If so, then the mixed cryoglobulins might represent Silva & Castro, 1963). intermediate products of host defence, the possibly 1 See also Almeida, J. 0. (1963) Work conference on the pathogenic antigen-IgG antibody complex having serology of leprosy; unpublished Pan-American Health been successfully trapped in them by the " second Organization working document RES.63.3. 800 0. WAGER

(5) Renal lesions appeared in relation to the Since Myco. leprae is the etiological agent of reactional phases of lepromatous leprosy; they began leprosy, more knowledge is greatly needed of its with proteinuria, which progressed eventually to antigenic constituents, and also of those, possibly renal failure (Granells, 1968). In a single patient with useful, cross-reacting antigens from other mycobac- lepromatous leprosy, proteinuria appeared on the teria that are more easily propagated in vitro than the fourth day of the clinical ENL reaction (Turk, capriciously fastidious Myco. leprae. The studies by personal communication). Ouchterlony and his co-workers (Norlin et al., 1966), (6) Cryoglobulinaemia occurs in 50 %-90 % of being based on vast experience in the use of sophisti- patients with lepromatous leprosy (Matthews & cated analytical gel-diffusion techniques, may be Trautman, 1965; Bonomo & Dammacco, 1968 and regarded as most promising from this point of view. personal communication). The cryoglobulins isolated The still-imperfectly understood life-cycle of the from the sera of 2 patients with lepromatous leprosy etiological agent of leprosy, manifesting itself as the were characterized by immunoelectrophoresis as acid-fast Myco. leprae bacillus when thriving in IgM-IgG (Bonomo & Dammacco, personal com- lepromatous human tissue, should also be given due munication). consideration (Barksdale, personal communication). Finally, the importance of mutual exchange of Removal of cryoprecipitate abolished the rheu- information extracted from the immunopathological matoid factor, thyroid antibody and the VDRL study of the collagen diseases, on the one hand, and activities of the parent lepromatous leprosy sera from that of leprosy, on the other, cannot, in the (Matthews & Trautman, 1965). Antinuclear factor opinion of the writer, be stressed too much. activity disappeared from the lepromatous leprosy Detailed research plans do not fall within the sera on storage at +4°C (Bonomo & Dammacco, scope of this general report but some suggestions for personal communication). the partially overlapping main lines of future im- The observations mentioned above are all com- munopathological study of leprosy are summarized patible with the presence and activities of the below. postulated immune complexes. However, much more information than that available at the present time is (1) Further extension of the studies of the AM needed to replace speculation by valid conclusions. (bursa-dependent) immunological aberrations, including cryoimmunoglobulinaemia, by the methods FUTURE LINES OF RESEARCH of modern immunology, as already successfully applied by Bonomo and his co-workers (Bonomo & From the immunopathological point of view, the Dammacco, 1967, 1968 and personal communica- same general rules apply to the study of leprosy as to tion; Bonomo, Dammacco & Gillardi, 1968; Bonomo that of the autoimmune diseases sensu stricto, say, et al., 1963, 1965, 1967). SLE and rheumatoid arthritis. Intensive research on (2) Confirmation and extension of the recent the latter has alkeady resulted in most valuable challenging observations by Turk and his co-workers information be ng assembled, strongly suggesting an (Turk, 1968; Turk & Waters Turk & essential role in 1968; pathcgenic for immune mechanisms Willoughby, 1967) suggesting a genetically determi- these diseases. The study of leprosy by modern im- ned general depression of the CM (thymus-depend- munological methods, however, has just begun but immune in this disease, compared with the autoimmune diseases, ent) responses lepromatous leprosy. offers the advantage of known etiology. (3) Tracing of the reactants in the postulated Studies to be carried out in the field of the immu- immune complex-caused tissue damage in lepro- nopathology of leprosy, therefore, should aim at matous leprosy. identifying the postulated participants (immuno- (4) Isolation and characterization of soluble globulins, complement, mycobacterial antigens) in antigenic components from Myco. leprae and other, the possibly pathogenic immunological events at the cross-reacting mycobacteria. sites of lesions, and also at tracing the pathways of reactions leading to the lesions of the target tissue. (5) Further development and analysis of the To this end, immunofluorescent techniques (and experimental model of Myco. leprae-caused disease in possibly other tracer-labelling techniques) should be mice, with particular reference to the immunological the methods of choice. aberrations possibly associated with it. IMMUNOLOGICAL ASPECTS OF LEPROSY 801

(6) Exploration of the life-cycle of Myco. leprae, recent progress made in the methods of cultivation of e.g., search by tracer-labelling methods of Myco. other fastidious micro-organisms, e.g., viruses and leprae-specific defined antigens (see under (4) above) mycoplasmas (Hoorn, 1966; Jansson & Wager, 1967), from tissue sections free of acid-fast bacilli. may encourage microbiologists to continued efforts (7) Despite frustrations associated with previous at creating in vitro conditions acceptable to this true attempts at in vitro cultivation of Myco. leprae, the devotee among microbes of live human tissue.

RESUME LES ASPECTS IMMUNOLOGIQUES DE LA L-PRE DANS LEURS RAPPORTS AVEC LES MALADIES AUTO-IMMUNES

La lpre, en particulier sous sa forme lepromateuse, globulines (95 %), reactions serologiques faussement posi- s'accompagne d'un tres grand nombre d'anomalies immu- tives pour la syphilis (70%), faible taux de complement nologiques et ses aspects cliniques rappellent a maints (50 %). Les auto-anticorps circulants ne font probable- egards ceux que l'on observe dans les maladies du ment pas preuve d'une nocivite directe pour F'h6te, mais colUagene. les immun-complexes contenant des auto-anticorps Plusieurs faits plaident en faveur d'une hyporeactivite, peuvent avoir un effet pathogene. d'origine genetique, de l'immunit6 a support cellulaire On dispose d'un certain nombre de donnees experi- chez les malades 1epromateux. Outre l'absence de reac- mentales concernant le pouvoir phlogogene des complexes tion aa' l6promine, on observe chez ces patients toute antigene-anticorps et leur r6le pathogene dans les mala- une serie de phenomenes explicables par la carence de dies auto-immunes. Les cryo-immunoglobulines mixtes cette immunite: sensibilite amoindrie vis-a-vis de divers (formees de deux (IgG-IgM ou IgG-IgA) ou de trois antigenes lors des tests cutanes; affaiblissement de la immunoglobulines) mises en evidence dans le lupus capacite de transformation des lymphocytes; retard dans erythemateux et dans certaines maladies microbienes A le rejet des homogreffes cutanees; presence, au niveau composantes auto-immunitaires (syphilis, nephrite et des ganglions lymphatiques, d'alterations histologiques endocardite streptococciques, mononucleose infectieuse, comparables a celles qui succedent chez le cobaye a pneumonie a Mycoplasma pneumoniae) representent peut- l'administration de s6rum anti-lymphocytes. Toutefois, etre des immun-complexes circulants. on ne peut exclure completement la possibilite que cet Dans la lepre egalement, diverses observations sug- affaiblissement de l'immunite a support cellulaire resulte gerent l'existence d'immun-complexes pathogenes: pre- d'une action directe de l'infection par Mycobacterium sence de cryoglobulines mixtes, analogies entre les lesions leprae. Quant aux observations qui font etat d'une stimu- locales de l'erytheme noueux lepreux et celles du phe- lation generale des mecanismes immunitaires assurant la nomene d'Arthus, episodes reactionnels generaux rap- production des anticorps circulants, elles sont fragmen- pelant la maladie du serum, activite anticomplementaire taires et doivent etre interpretees avec prudence. transitoire, diminution de l'activite du complement et de Apres avoir brievement rappele les conceptions actuelles sa teneur en certains constituants, presence d'antigenes relatives a l'auto-immunite et les criteres qui permettent mycobacteriens dans le serum, concomitance de l'appa- de classer une affection dans le groupe des maladies auto- rition des lesions renales et des episodes r6actionnefs. immunes, I'auteur enumere certaines anomalies (sem- Les recherches sur l'immunopathologie de la lepre blables A celles que l'on rencontre dans le lupus erythe- doivent etre conduites selon les memes principes que les mateux dissemine et dans l'arthrite rhumatolde) dont etudes consacrees aux maladies auto-immuries sensu l'incidence est particulierement elevee dans la lepre stricto. Les principaux secteurs vers lesquels cette lepromateuse: facteurs antinucleaire (30 %) et rhuma- recherche devrait etre orientee sont succinctement tolde (50%), anticorps anti-thyreoglobuline (40%), cryo- evoques.

REFERENCES

Abruzzo, 0. & Christian, C. L. (1961) J. exp. Med., 114, Aho, K. & Wager, 0. (1961) Ann. Med. exp. Fenn., 39, 79 791 Almeida, J. 0. (1963a) Int. J. Leprosy, 31, 609 Aho, K. (1961) Ann. Med. exp. Fenn., 39, suppl., p. 7 Almeida, J. O., Brandao, H. & de Lima, E. G. (1964) Aho, K., Konttinen, A., Rajasalmi, W. & Wager, 0. Int. J. Leprosy, 32, 292 (1962) Acta path. microbiol. scand., 56, 478 Almeida, N. C. & Silva, C. (1963) Int. J. Leprosy, 31, 540 802 0. WAGER

Azevedo, M. P. de & Melo, P. H. de (1966) Int. J. Leprosy, Estrada-Parra, S., Rojas-Espinosa, 0. & Reyez-Gomez, P. 34, 34 (1968) Isolation ofpolysaccharides from M. leprae and Bonomo, L. & Dammacco, F. (1967), Immunology, 13, M. lepraemurium and their reaction with sera from 565 patients with leprosy. In: Transactions of the 9th Inter- Bonomo, L. & Dammacco, F. (1968) Protein changes and national Leprosy Congress, London (Int. J. Leprosy, 36, immunity in some chronic infectious diseases. In: No. 4, Pt. 2, abstract, Miscellaneous 231) Chini, V., Bonomo, L. & Sirtori, C., ed., Proceedings Forsen, N. R. & Barnett, E. V. (1968) Arthr. and Rheum., of the International Symposium on Gammapathies, 11, 479 Infection, Cancer and Immunity, Milan, Carlo Erba Gell, P. G. & Coombs, R. R. A., ed. (1963) Clinical Foundation aspects of immunology. Oxford, Blackwell p. 580 Bonomo, L., Dammacco, F. & Gillardi, U. (1968) Int. Goihman-Yahr, M., Raffel, S. & Ferraresi, R. W. (1968) J. Leprosy (in press) Passive transfer of lepromin sensitivity. In: Trans- Bonomo, L., Dammacco, F., Pinto, L. & Barbieri, G. actions of the 9th International Leprosy Congress, (1963) Lancet, 2, 807 London (Int. J. Leprosy, 36, No. 4, Pt. 2, abstract VIII Bonomo, L., Dammacco, F., Tursi, A. & Barbieri, G. 102) (1967) Int. J. Leprosy, 35, 65 Granells, M. (1968) Renal lesions in leprosy. In: Trans- actions of the 9th International Leprosy Congress, Bonomo, L., Tursi, A., Trimigliozzi, G. & Dammacco, F. London (Int. J. Leprosy, 36, No. 4, Pt. 2, abstract XIV (1965) Brit. med. J., 2, 688 181) Buck, A. A. & Hasenclever, H. F. (1963) Amer. J. Hyg., Guinto, R. S. (1968) Nature of the negative Mitsuda 77, 305 reaction in lepromatous leprosy. In: Transactions ofthe Bullock, W. E. (1968) New Engl. J. Med. 278, 298 9th International Leprosy Congress, London (Int. J. Burnet, M. (1968) Lancet, 2, 610 Leprosy, 36, No. 4, Pt. 2, abstract VIII 93) Castro, N., Silvera, S. M. & Castro, N. (1963) Int. J. Guinto, R. S. & Mabalay, M. C. (1962) Int. J. Leprosy, Leprosy, 31, 573 30, 278 Catsoulis, E. A., Franklin, E. C. & Rothshild, M. A. Hanauer, L. B. & Christian, C. L. (1967) J. clin. Invest., (1965) Immunology, 9, 327 46, 400-408 Christian, C. L. (1965) Rheumatoid arthritis. In: Samter, Hart, P. D. & Rees, R. J. W. (1967) Brit. med. Bull., 23, M., ed., Immunological diseases, Boston, Little Brown, 80 p. 725 Hoorn, B. (1966) Acta path. microbiol. scand., 66, Christian, C. L., Hanauer, L. B. & Pincus, T. (1967) suppl., p. 183 Systemiclupus erythematosus-immune complexdisease? Houba, V., Adam, M., Malacek, J. & Tesarek, B. (1964) In: Miescher, P. A. & Grabar, P., ed., Immuno- Experentia (Basel), 20, 522 pathology, 5th International Symposium, Basel, Schwabe Jansson, E. & Wager, 0. (1967) Ann. N. Y. Acad. Sci., Co., p. 83 143, 535 Cochrane, C. G., Hawkins, D. & Kniker, W. T. (1967) Khoshoo, P. N. (1968) Prevalence of tuberculosis among Mechanisms involved in the localization of circulating leprosy patients. In: Transactions of the 9th Inter- immune complexes in blood vessels. In: Miescher, P. A. national Leprosy Congress, London (Int. J. Leprosy, 36, & Grabar, P., ed., Immunopathology, 5th International No. 4, Pt. 2, abstract 11I11) Symposium, Basel, Schwabe, p. 32 Koffler, D., Schur, P. H., Kunkel, H. G. & Graf, M. (1967) Evidence for the renal deposition of antigen- Coombs, R. R. A., Coombs, A. M. & Ingram, D. G. antibody complexes in patients with systemic lupus (1960) The serology of conglutination and its relation to erythematosus. In: Miescher P. A. & Grabar, P., ed., disease. Oxford, Blackwell Immunopathology 5th International Symposium, Basel, Cooper, M. D., Gabriel, A. E., Snr, & Good, R. A. (1967) Schwabe, p. 70 Ann. Rev. Med., 18, 113 Kunkel, H. G. & Tan, E. M. (1967) Advanc. Immunol., Dierks, R. E. & Shepard, C. C. (1968) Proc. Soc. exp. 4, 351 Biol. (N. Y.), 127, 391 Lerner, A. B., Barnum, C. P. & Watson, C. J. (1947) Dixon, F. J. (1962-63) The role of antigen-antibody com- Amer. J. med. Sci., 214, 416 plexes in disease. In: The Harvey Lectures, New York, Loghem, J. J. van (1966) Discussion. In: Grabar, P. & Academic Press, Series 58, p. 21 Miescher, P. A., ed., Immunopathology, 4th Inter- Dixon, F. J. (1965) Ann. N. Y. Acad. Sci., 124, 162 national Symposium, Basel, Schwabe, p. 411 Dixon, F. J., Edgington, T. S. & Lambert, P. H. (1967) LoSpalluto, J., Dorward, B., Miller, W. Jr & Ziff, M. Non-glomerular antigen-antibody complex nephritis. (1962) Amer. J. Med., 32, 142 In: Miescher, P. A. & Grabar, P., ed., Immunopa- Lurie, M. B. (1964) Resistance to tuberculosis, Cam- thology, 5th International Symposium, Basel, Schwabe, bridge, Mass., Harvard University Press p. 17 Mackay, J. R. & Burnett, F. M. (1963) Autoimmune Eliasberg, J. (1911) Dtsch. med. Wschr., 37, 302 diseases, Springfield, Charles Thomas, p. 16 IMMUNOLOGICAL ASPECTS OF LEPROSY 803

Matthews, L. J. & Trautman, J. R. (1965) Lancet, 2, 915 Sheagren, J. N., Block, J. B., Trautman, J. R. & Wolff, Meltzer, M. & Franklin, E. C. (1966) Amer. J. Med., S. M. (1967) Clin. Res., 15, 300 40, 828 Silva, C. & Tuma, M. (1960) Rev. bras. Leprol., 28, 17 Michalany, J. (1966) Int. J. Leprosy, 34, 274 Tan, E. M., Schur, P. H. & Kunkel, H. G. (1965) J. clin Miescher, P. A., Paronetto, F. & Koffier, D. (1966) Invest., 44, 1104 Immunofluorescent studies in human vasculitis. In: Turk, J. L. (1968) The immunological basis ofreactions in Grabar, P. & Miescher, P. A., ed., Immunopathology, leprosy. In: Transactions of the 9th International 4th International Symposium, Basel, Schwabe, p. 446 Leprosy Congress, London (Int. J. Leprosy, 36, No. 4, Mustakallio, K. K., Lassus, A. & Wager, 0. (1967) Int. Pt. 2, p. 628, abstract XII 141) Arch. Allergy, 31, 417 Turk, J. L. & Waters, M. F. R. (1968) Lancet, 2, 436 Myllyla, G., Vaheri, A., Vesikari, T. & Penttinen, K. Turk, J. L. & Willoughby, D. A. (1967) Lancet, 1, 249 (1969) Clin. exp. Immunol., 4, 323 Unanue, E. R. & Dixon, F. J. (1967) Advanc. Immunol., Navalkar, R. G. (1968) Immunologic analysis ofM. leprae 6, 1 antigens and human sera by means of gel-diffusion Vaughan, J. H. (1959) Amer. J. Med., 26, 596 methods. In: Transactions of the 9th International Vaughan, J. H. (1965) Introduction to Part 4; diseases Leprosy Congress, London (Int. J. Leprosy, 36, No. 4, with immunological features. In: Samter, M., ed., Pt. 2, abstract VIII 97) Immunological diseases. Boston, Little Brown, p. 723 Newell, K. W. (1966) Bull. Wld Hlth Org., 34, 827 Wager, 0. (1950) Ann. Med. exp. Fenn., suppl. p. 12 Norlin, M., Navalkar, R. G., Ouchterlony, 0. & Lind, A. Wager, O., Mustakallio, K. K. & Rasanen, J. A. (1968) (1966) Acta path. microbiol. scand., 67, 555 Amer. J. Med., 44, 179 Oleinick, A. (1968) Cancer mortality among leprosy Wager, 0. & Rasanen, J. A. (1969) Mixed cryoimmuno- patients. In: Transactions of the 9th International globulinemia in relation to autoimmune aberrations. In: Leprosy Congress, London (Int. J. Leprosy, 36, No. 4, Transactions ofthe International Symposium on Immune pt. 2, abstract 11 13) Complex Diseases, Spoleto, Carlo Erba Foundation Oort, J. & Turk, J. L. (1965) Brit. J. exp. Path., 46, 147 Wager, O., Rasanen, J. A., Hagman, A. & Klemola, E. Panel on Lepra Reaction (1963) Report. In: Proceedings (1968a) Int. Arch. Allergy, 34, 345 of the 8th International Leprosy Congress, Rio de Wager, O., Rasanen, J. A., Hagman, A. & Mustakallio, Janeiro (1963) (Int. J. Leprosy, 31, 480) K. K. (1968b) Kryoimmunoglobulinemi och auto- Parrott, D. M. V., de Sousa, M. A. B. & East, J. (1966) immunitet. In: Transactions of the XII Scandinavian J. exp. Med., 123, 191 Congress of Rheumatology, Helsinki, p. 37 Peetoom, F. & Loghem, E. van (1965) Vox Sang. (Basel), Wager, O., Rasanen, J. A., Lassus, A. & Mustakallio, 10, 281 K. K. (1967) Acta path. microbiol. scand., 69, 610 Penttinen, K. & Myllyla, G. (1968) Ann. Med. exp. Fenn., Waldorf, D. S., Sheagren, J. N., Trautman, J. R. & 46, 188 Block, J. B. (1966) Lancet, 2, 773 Rees, R. J. W., Chatterjee, K. R., Pepys, J. & Tee, R. D. Wasastjerna, C., Kalliala, H., Rasanen, J. A. & Wager, 0. (1965) Amer. Rev. resp. Dis., 92, 139 (1967) Scand. J. Haemat., 4, 473 Salvin, S. B. (1963) Progr. Allergy, 7, 213 Weigle, W. 0. (1961) Advanc. Immunol., 1, 283

Annex CLASSIFICATION OF ALLERGIC REACTIONS (modified from Gell & Coombs, 1963)

Type I (anaphylactic) Type III (Arthus) (a) General anaphylaxis. (a) Arthus reaction and serum sickness. (b) Local anaphylaxis (urticaria, Prausnitz-Kuestner (b) Toxic-complex syndromes (sensitivity to penicillin, reaction, asthma); mediated by IgE, complement not systemic lupus erthematosus, polyarthritis, cryoimmuno- involved. globulinaemia); mediated by Ag-Ab complexes invol- ving precipitating IgG, IgM and IgA, complement Type II (cytotoxic) involved. (a) Antigen of cell surface (transfusion reactions, haemolytic disease of newborn). Type IV (delayed) (b) Antigen attached to cell surface (apronal (Sedormid) (a) Tuberculin reaction and contact dermatitis. purpura); mediated by IgG, IgM and IgA, complement (b) Homograft rejection; mediated by specifically usually involved. modified mononuclear cells. 804 0. WAGER

MARKERS FOR AUTOIMMUNE DISEASE (modified from Mackay & Bumet, 1960)

(1) Hypergammaglobulinaemia (. = 2 g/100 ml). (5) Responsiveness to immunosuppressive drugs (ster- oids, mercaptopurine, etc.). (2) Autoantibodies (circulating or cell-fixed or both). (6) Co-existence of disease with other lesions attri- butable to autoimmunity. (3) Deposition of immunoglobulin or complement or both in affected tissue. None of the markers IS necessarily specific but occurring in combination they strongly suggest an autoimmune (4) Accumulation of lymphoid and plasma cells. process.