I N'I ER N A'\\Ot\ AL JUI ' HN A I. OF Lbl'ROSY Volume 4:1 . Number :1 Prillled ill rhe U. S', A , Comparison of Reactions to Human J and Armadillo Lepromins in Leprosy 1,2,4,5

W. M. Meyers, S. Kvernes and C. H. Binford 3

The ancient chronic disease of leprosy is sue naturally infected with M. /eprae. 6 This still a major health problem in many endem­ suspension contains whole M . /eprae and ic areas. The World H ealth Organization variable amounts of soluble tissues and bac­ estimates that there are more than ten mil­ illary extract a nd debris. The lepromin reac­ lion leprosy patients in the world today. tion has two components: the early, or Fer­ While there have been remarkable advances nandez ( 6) reaction (48 hours), and the late in the basic understanding of leprosy in the or Mitsuda reaction (four weeks). Early re­ past two decades, there remain several sig­ actions are equated generally with a pre­ nificant obstructions to progress in medical existing delayed hyperse nsiti vity to M. /ep­ management and epidemiology. One of rae and late reactions to either a pre-existing these barriers is the lack of adequate sup­ or a stimulated delayed hypersensitivity to plies of a standardized reagent (lepromin) injected antigen. Due to a marked variability for skin testing. Mycobacterium /eprae, the in the Fernandez reaction and poor correla­ causative agent of leprosy, has not been cul­ tion with clinical forms of leprosy, most lep­ tured in vitro and infected human tissue re­ rologists are re I ucta n t to attach s peci fic mains the sole source of lepromin. Only a clinical significance to this res ponse. An im­ small percentage of leprosy t rea t me n t cen­ portant exception to this is the reaction to ters utilize the lepromin reaction routinely, Dharmendra's lepromin (4), a purified chlo­ and in many of these centers the antigenic roform-ether-extracted suspension of M. /ep­ strength of the lepromin employed varies rae, which regularly produces only the 48- widely from acceptable standards. hour reaction. Such reactions generally carry The classic lepromin reaction, first studied the same significance as the M itsuda reac­ by Hayashi (1 0) and Mitsuda (1 5), is the cu­ tion to integral (M itsuda-Hayashi-Wade) taneous response to the intradermal injec­ lepromin. The Mitsuda reaction is uniformly tion of autoclaved suspensions of human tis- recognized to have particular usefulness in the clinical classification of leprosy patients

I Received for publicati o n 27 January 1975. and hence is of substantia l prognostic value. l Supported b \' American Le prosy Missio ns. In c .. 297 Considerable epidemiologic data have also Park Ave. Soulh. New Yo rk . N.Y. 10010. and by Grant bee n derived from studies of the lepromin AI-I 1-620-0 1 fro m the Nationa l Ins titut es o f Allergy reaction in whole popUlations and contacts. and In fectious Di seases. Be thesda. Maryland 200 14 . ' W . M . Meyers. M. D .. Ph. D .. Professor of Pathology. There is growing evidence that the clinical ALM l.e pros\' Atelier. Departme nt of Pa thology. Uni­ spectrum of leprosy correlates well with the versity o f Hawaii Sc hoo l of Med ici ne. H o nolulu. Ha­ level of cell-mediated immunity (CMI) to M . waii 96816: S . Kve rnes. M. D .. Director. Ki vu\' u l.epro­ /eprae ( 2. 19). Thus lepromatous patients sarium. Institut Medica l Evangeli que. Kimpese. Repub­ li c of Zaire: C H. Binford. M . D .. C hief. Special Myco­ demonstrate a marked depression of CMI bacte rial Diseases Branc h. Armed Forces Institute o f while tuberculoid patients react strongly, Patho logy. Washingto n. D.C 2 0~06 . Re print requests and borderline patients are intermediate. should be addressed to Dr. Meyers. De pl. o f In fectious Since Mitsuda reactions a re pro bably a clin­ a nd Pa rasitic Disease Pa tho logy. Armed Forces Insti ­ ical manifesta tion of CM I (1 ), they correlate tute of Pathology. Washington. D.C 20306. " The opinions o r a ssertions contained he rein arc the closely with the clinical forms of leprosy: private views o f the authors and arc not to be construed lepromatous patients give no or only weak as official o r as refle cting the vicws o f the De partme nt reactions; tuberculoid patients, strong reac- o f the Army o r the De partme nt o f Defense. 51n conducting the research d escribed in this report. the in vest igators adhered to the "Guide for La borator\' h A standa rd no me ncla ture for lepromins o f va ri o us Animal Facilities and Ca re." as pro mulgated by th ~ o ri g in s has not been formulated . In this paper we refcr eommillec o n the Guide for Laborato ry Animal Facil­ to the two lepromins we e mployed as fo ll ows: le promin iti es and Ca re or the Institut e of Labo ratory Animal d erived fr o m in fected human tissue as lepromin- H: and Resources. National Academy o f Sciences-National lepromin de ri ved from infected armadillo tiss ue as le p­ Researc h Cou ncil. romin-A.

218 43,3 Meyers er al: Comparison of Human and Armadillo Lepromins 219 tions; and borderline patients, intermediate the leprosy care facility of the I nstitut Me'di­ reactions. A precise immunologic class ifica­ cal Evange'lique at Kimpese, Republic of tion of each leprosy patient is perhaps the Zaire. All patients were Bantu: 113 of the most importa nt concern of the clinician in Kongo tribal group and 2 Mbundu. Fifty­ developing a rational program of treatment three were Zairian and 62 Angolan. Age and for the individual patient. sex distributions are shown in Table I. Lepromins prepared from M . /eprae in­ Where age could not be established, esti­ fected mouse ( 5) and chipmunk (14) tissues mates were made to the nearest five years. produce reactions in leprosy patients com­ Admission diagnoses and classification of parable to those obtained with lepromin-H. leprosy patients (Table 2) were based on the However, adequate supplies of such tissues criteria summarized by Ridley and J o pling for the manufacture of large quantities of (1 7). These criteria are: clinical features, lepromin for general clinical use are not ex­ bacteriologic density of skin smears, lepro­ pected to be forthcoming. The development min reactio n (lepromin-H), and hi stologic of M. leprae infections in armadillos (II. 12) features. We employed the designations of has made available for the first time large Ridley and Jopling in classifying patients: volumes of infected tissues for lepromin pro­ LL, lepromatous; BL, borderline-leproma­ duction. We report here the results of our tous; BB, borderline; BT, borderline-tuber­ study of reactions to lepromin-A and lepro­ culoid; and TT, tuberculoid. Fifty-three min-H in leprosy patients, performed pri­ patients had never received antileprosy marily to assess the usefulness of lepro­ therapy, sixty had received sulfone therapy min-A as a substitute for lepromin-H. for one month to nine years, and one had been on c10fazimine for one month. One pa­ tient was classified as healed and had been MATERIALS AND METHODS off therapy for 15 years. Five patients (four Leprosy patients. Between November LL and one BB) were receiving prednisolone 1973 and October 1974 we lepromin-tested on an alternate day program during the lep­ 115 leprosy patients registered at Kivuvu, romin testing. Thirty-nine patients had had one previous lepromin test (lepromin-H) six T A BLE I . Age and sex distribution months to eight years prior to the tests re­ of leprosy patients. ported here. We are uncertain of the BeG vaccination history of each patient. None of Age (years)" Ma le Female the patients had clinical evidence or a known 11-14 2 I history of tuberculosis or other mycobacte­ 15-24 4 7 rial disease except for leprosy. 25-34 II 8 The armadillo is not native to Zaire or 35-44 20 18 Angola and none of the patients studied had 45-54 15 7 had contact with armadillos or products of 55-64 9 7 the armadillo prior to this study. 65-70 2 4 - Preparation of lepromins. Lepromin-H Total 63 52 was prepared from pooled lepromas excised from three untreated leprosy patients re­ "Average age 40.1 years. Age range II to 70 years. cently admitted to Kivuvu. Lepromin-A was produced from heavily infected tissue of a TABLE 2. Distribution olpatients nine-banded armadillo (Dasypus novemcinc­ by class of leprosy. tus) which had been injected with an homog­ enate of human lepromas from a patient in C la ss" No. pati ents Percent Surinam. The human lepromas used to pre­ pare the inoculum for this armadillo were LL 39 34. BL 8 7 provided by Dr. S. J . Bueno de Mesquita, BB 2 1 18 Paramaribo, Surinam. The infected arma­ BT 19 17 dillo tiss ue (Animal #L-5), and normal arma­ dillo tissues were kindly supplied by Dr. TT 28 - 24 Tota l 11 5 100 G. P. Walsh and Dr. E. E. Storrs of Gulf South Research Institute, N~w Iberia, Loui­ "Sec text for class notations. siana. 220 International Journal of Leprosy 1975

We employed the Mitsuda- Hayashi-Wade The Fernandez reaction was read at 48 technic (1 8) to pre pare both lepromins. hours, and the M itsuda reacti o n at 28 days, Phenol (0.5%) was used as a preservative and recorded as the width of induration at and both preparations were stored at 0-4°C the injected si te measured at 90° to the long throughout the study. Acid-fast bacillary axis of the forearm. We obtained biopsy counts were kindly performed by Dr. John specimens (7 mm) of both the lepromin-H Hanks, John Hopkins University School of and lepromin-A reactions at 28 days from 42 Medicine, Baltimore. The relative propor­ patients and evaluated hematoxylin-eosin tions of soluble protein of tiss ue and bacte­ and Fite-Faraco stained sections. The test rial origin in this preparation are not known. site in lepromatous patients, frequently in­ A control normal armadillo extract was apparent at 28 days, was identified by the prepared from autoclaved homogenates or intraderma l inj ection of minute amounts of subcutaneous tiss ue and muscle and pre­ sterile India ink one cm proximal to the served with phenol (0.5%). point of lepromin injection. When normal Lepromin testing. The lepromin-H used armadillo tissue extract was employed, the throughout the study contained 175 million injections were made in the same manner as bacilli/ m!. This is slightly stronger than those for the lepromins at a point about five "standard" lepromin (160 million bacilli / ml) cm proximal to the lepromin-A test site. In recommended at the Eighth International all cases where a pa tien t was to receive a Congress of Leprology (Rio de Janeiro, repeat injection with either lepromin-A or 1963). The initial 22 patients were tested armadillo tissue extract, or any sequential with lepromin-A containing 220 million ba­ combination of these reagents, a prior intra­ cilli / ml; for the remaining 93 patients this dermal test injection of 0.1 ml of a 1/ 100 di­ suspension was adjusted to 175 million ba­ lution of armadillo extract was administered cilli / m!. The human and armadillo prepara­ and the patient observed for at least one tions contained, respectively, II % and 6% hour. solid staining bacilli, which is assumed to be a measure of viable M. leprae in each origi­ RESULTS nal tissue. One-tenth ml of lepromin-H was In this series of leprosy patients (epresent­ injected intradermally on the flexor surface ing the complete spectrum of established of the right forearm and an equal volume of clinical forms of the disease, we noted the lepromin-A was injected intradermally at classic response to both lepromin-H and lep­ the same sitting at the corresponding site of romin-A (Table 3), i.e., the intensity of the the left forearm. Since only rarely was more Mitsuda reactions progressed from a mini­ than one patient tested on the same day, the mal response in LL patients to maximal same syringe, filled to the same level, was levels in TT patients. In patients grouped used almost exclusively for each reagent. according to class of leprosy, lepromin-A Lepromin ampoules were well shaken before consistently provoked a more intense Mi­ filling the syringes and injections were made tsuda response than lepromin-H. The differ­ immediately. These precautions were ob­ ences are significant for all categories of served to minimize dosage variations (8). patients except the small group of BL pa-

TABLE 3. Comparison of Mitsuda reactions to lepromin-H and lepromin-A .

Class Lepromin-H Lepromin-A Diff. of Sig.b means a Patients Meana S.D. Patients Meana S.D. All patients 112 5.8 4.89 III 8.2 6. 12 2.4 < .005 LL 39 1.5 1.93 38 2.6 2.19 1.1 < .005 BL 7 4.1 1.24 7 4.7 2. 18 0.6 NS BB 20 5.3 2.45 20 7.6 3.40 2.3 < .025 BT 18 8.4 2.77 18 11 .3 3.72 2.9 < .05 TT 28 11 .0 4.87 28 15 .1 5.10 4. 1 < .005

a Millimeters of induration. bt-test (two-tailed). 43 , 3 Meyers el al: Comparison of Human and Armadillo Lepromins 221

tients tested. Figure 1 demonstrates the Mi­ tsuda reactions to both lepromin-H and lep­ romin-A and a 28-day reaction to armadillo tissue extract in a TT patient. Although of doubtful practical usefulness, we have tabulated the results of the Fernan­ dez reactions in Table 4. Reactions to lepro­ min-A again were consistently larger than those to the lepromin-H. In grouped patients these di(ferences were significant in all but the BL and TT patients. FIG. I. Skin reactions, 28 days postintradermal Reactions to the original lepromin-A (220 injection to lepromin-H, lepromin-A and normal million bacilli / ml) and the diluted (175 mil­ armadillo ti ssue extract in a tuberculoid leprosy lion bacilli/ ml) preparations are compared patient, class TT. These reactions measured as in Table 5. Lepromin-A produced stronger follows: lepromin-H, 10 mm; lepromin-A, 17 mm; Fernandez and Mitsuda reactions than lep- armadillo extract, 5 mm. AFIP 75-4760-4.

TABLE 4. Comparison of Fernandez reactions to lepromin-H and lepromin-A.

Class Lepromin-H Lepromin-A Diff. of Sig.b means" Patients Mean " S.D. Patients Mean"· S.D. All pa ti ents 112 4.7 2.94 109 6.6 2.78 1.9 < .001 LL 39 3.6 2.24 38 5.7 1.92 2.1 < .001 BL 7 5.4 2.38 6 6.7 1.60 1.3 NS BB 20 4.6 2.25 20 6.2 2.22 1.6 <.05 BT 18 4.8 2.48 17 6.5 1.45 1.7 < .025 TT 28 6.0 3.63 28 7.1 2.91 1.1 NS

"Millimeters of induration. bt-tes t (two-tailed).

TABLE 5. Comparison of reactions to a standard lepromin-H (/75 x 106 bacilli/ ml) and two concentrations of lepromin-A .

FERNANDEZ REACTION Lepromin-H Lepromin-A Baci llary concentration Diff. of Patients Mean" S.D. lepromin-A Patients Mean" S.D. means· Sig.b

22 5.3 2.96 220 x 10bj ml 22 8.0 2.95 2.7 < .01 90 4.5 2.85 175 x 10 1> / ml 87 6.2 2.61 1.7 < .00 1

MITSUDA REACTION

22 220 x 10 l> j ml NS 90 175 x 10 l> j ml < .025

" Millimeters of induration. ht- test (two-tailed). 222 International Journal of Leprosy 1975 romin-H at both concentra ti o ns of lepro­ that normal a rma dillo ti ss ue components min-A; however, the differences a re less at pa rtic ipa te in the reacti o n to lepromin-A. equal bacilla ry concentrati ons. T hi s stresses This is pa rticula rl y true in the BT a nd TT the importa nce o f a strict c ontro l of bacil ­ pati ents. There is no convincing evid ence la ry counts of each lepro min preparati on that previous ex pe rie nce with lepromin-A employed. regularl y se nsitized leprosy patients to a r­ Table 6 gives individual res po nses to nor­ madillo ti ss ue. However, seven of the eight mal a rmadillo extract compa red with lepro­ pati ents who had previous contact with lep­ min-A in 35 patients of the different cl asses romin-A had borderline or lepromatous lep­ of leprosy. The results of this se ri es suggest rosy and may have been less capable of

T A BLE 6. Co mparison of reactions to lepromin-A and normal armadillo tissue extract in individual leprosy patients.

Class Lepromin-A" Norma l a rmadillo extract" 48 hours 28 days 48 ho urs 28 days

LLc 8 5 - 0 7 2 10 0 5 5 0 0 7 6 3 3 7 0 4 0 5 0 4 0 6 3 3 0 5 0 0 0 4" 5" 6 0 7" 4 " 3 0 BL 8 - -4 4" 7" 7 0 6" 5 b 3 0 BB 8" 7 b 4 I 7 5 - 0 4 6 7 3 8 3 8 0 4" 8" 4 3 8" 7" 7 0 BT 6 20 5 14 5 II 2 4 8 - 5 - 6 14 0 7 4 8 2 5 6 13 3 6 6 II 2 6 10 10 I 5 9 15 - 8 TT 18 28 8 15 0 8 - 10 6 9 - 0 8 17 - 5 6 13 3 6 4 19 0 13 6b 9" 5 0

"A ll reacti ons in millimeters. b Va lu es from a previous lepromin-A tes t. All other patients were inj ected with leprom in-A and norma l a rl11 a­ dill o ex tract simultaneously. C Of the ten LL patients. four show M it sud a reacti ons of 5 or 6 ml11 . T hese reacti ons we re 2 to 3 ml11 to lepro l11in-H a nd a ll we re long-standing lepro l11 atous patient s who may be showing an upgrading of their immunologic statu s. T hus the initi al diagnos is of LL leprosy in these patients does not connict with these data. 43, 3 Merer.\· e/ al: COlllparison 01' Human and A rmadillo Lepromim' 223

8 F IG. 2. Comparison of t issue rcactions at 28 days to Icpromin- H (A), a'ld Icprom in-A ( B), in a tuber­ cul o id Icprosy paticnt, class TT. React ions are simil ar and are characterized by foci of cpithelioid cell s with a few giant ce ll s s u rrounded by Iymp h ocy tcs. H & E sta in, X165. AF IP (A) 74-632 1 a nd ( 8 ) 74-63 19. developing a sen si ti vity tha n patients with reacti on must be emphasized . T he world­ higher resista nt forms of leprosy. T he one wide distribution of sta nda rdi zed lepromin TT pa ti e nt who had a repeat injectio n of would permit clinicians everywhere to assess a rmadillo ti ss ue, did not react. the status of CM I in their pa ti ents a nd pla n In a no ther series of 36 pa ti e nts of a ll a regimen of o ptimal therapy a nd ma nage­ cl asses of leprosy, we injected a second dose ment. T he res ults of clinical d rug trials a nd of both le pro m in- H a nd le pro min-A six to "immunizatio n" a ttempts (e.g. , BCG vacci­ eight wee ks a ft e r the initia l test w ith the na tio n) in diffe re nt geogra phic a reas a nd same reagents. T here were no significant different ethnic groups may be more mean­ differences in the earl y o r late readings to ingful with the added info rma ti o n obtained lepromin- H o r lepromin-A in the repeat test. fr om reactio ns to a sta nda rdized lepromin. This se ri es provides additional evidence that A single in fec ted a rma d ill o can pro ba bly the a rma dillo tissue compo nent of lepro­ supply enough M. leprae fo r 15 million doses min-A pro ba bly has a low se nsitizi ng poten­ of lepromin. T hus there is every ex pecta ti on tial when used in this way. One LL pa tient, that a sta nd a rdized lepromin-A ca n be sup­ however, was elimina ted from the study be­ plied in a mounts adeq ua te fo r wo rld need . ca use a wheal d evelo ped a t the sit e of the The re a re, however, ma ny facto rs w hi c h injecti o n of a 1/ 100 dilutio n of normal a r­ must be in vestigated before lep romin-A can madillo extract within 30 minutes. T here was be introduced for ge neral use. In fact, lepro­ no systemic reacti on in this pa tient. min-H has not yet been satisfactoril y sta n­ Hi stologic evaluations of the bi o psy speci­ dardized, nor has the o ptimal d osage been mens of M its uda reacti ons to lepromin- H determined (9). a nd lepromin-A, over the ra nge of the clini­ ca l forms of leprosy, revealed simila r cellu­ T he two most urgent needs fo r the devel­ la r res po n ses in each insta n ce. F ig ure 2 o pment of a suita ble lepromin-A a re: I) re­ shows the simila rity of the hi sto pathologic moval of as much soluble a rmadillo ma terial features of reactio ns to lepro min- H a nd lep­ a nd ti ss ue debris as possible, a nd 2) to deter­ romin-A in a TT pa tient. One late reacti on mine the most sta ble method of storage. Our to a rmadillo tissue extract was bio psied . T hi s studies suggest tha t armadillo tissue in crude specimen was fro m a TT pati ent a nd showed Mit s ud a-H ayashi-Wa d e lepromin-A m ay a n inte n se gia nt ce ll , e pitheli o id cell a nd contribute to a n enha nce ment of the lepro­ lymphocytic res po nse, quite simila r to those min reacti o n a nd hence diminish the speci­ in Fi gure 2. fi cit y of the reagent. T hi s is not unexpected since " p ositive" skin reacti o ns to normal DIS C US SION huma n ti ss ue have been reported in leprosy The clinica l impo rta nce of the lepromin patients. These reactions, studied by Kooij 224 International jour/tal 0/ Leprosy 1975 and Gerritsen (13), were more frequent and tes comprendfa todas las formas clfni cas de lepra. more pronounced in tuberculoid leprosy pa­ La Icpromina derivada de armadillo (Iepromina­ tients, as were those we observed to normal A) produjo el mismo patrdn de respuestas que armadillo ti ss ue . Methods of storage of lep­ la lepromina derivada de humanos (Iepromina- H), romin have been studied by Abe et al (I) o sea , los pacientes lepromatosos dieron las reac­ ciones mas debiles y los pacientes tuberculoides who showed that lyophilized lepromin-H las reacciones mas fuertes. Las reacciones a la may be stable for at least five years. Studies Lepromina-A fueron consistentemente mas in­ of purified lyophilized lepromin-A are there­ tensas que las ala Lepromina-H. Conclufmos que fore urgently needed. la Lepromina-A es una alternativa promisoria In addition to the clinical usefulness of para la Lepromina-H, que puede hacer posible lepromin-A, our findings help confirm that una distribucidn mundial de un a ntfgeno estan­ the acid-fast bacillus in the infected arma­ dardizado para pruebas cutaneas. dillo is M. leprae. No other known acid-fast bacillus 'gives the classic lepromin response pattern over the clinical spectrum of forms of leprosy. In a limited study, Convit and Dans Ie but d'evaluer I'utilit e des ti ssus d'ar­ madillos infectes par Mycobacterium leprae. Pinardi (3) found that lepromin-A produced comme su bstit ut de lepromes humains po ur la reactions only in tuberculoid leprosy pa­ fabrication de lepromine, on a compare des reac­ tients. Thus the evidence to date that the tions cutanees a des preparations obtenues a acid-fast bacilli in the infected armadillos partir de ces deux sources. Cette etude a ete me­ are M. leprae is as follows: I) pattern of re­ nee chez 115 malades de la It-pre. L'echantillon action to lepromin-A in leprosy patients, 2) de malades comprenait toutes le s formes c1i­ pyridine extractability of acid-fastness (18) niques primaires de la It'pre. La lepromine de­ and the dopaoxidase activity (16) of bacilli rivee de I'armadill o (Iepromine A) a entratne Ie recovered from infected armadillo tissue, meme type de reponse que la lepromine d'origine and 3) selective invasion of nerves in the ar­ humaine (Iepromine H), c'est a dire que les ma­ lades lepromateux ont presente des reactions les madillo by the acid-fast bacilli (II). plus faibles et les malades tuberculo'ides les reac­ SUMMARY tions les plus fortes. Les reactions a la lepromine A ont ete regulit'rement plus prononcees que To assess the usefulness of Mycobacte­ celles a la lepromine H. On en conclut que la rium leprae-infected armadillo tissue as a lepromine A constitue une alternative pleine de substitute for human lepromas for the manu­ promesses pour la lepromine H, et pourrait ren­ facture of lepromin, we compared skin reac­ dre possi ble une distribution a I'echelle mondiale tions to preparations from these two sources d'un reactif cutane standardise pour les epreu­ in 115 leprosy patients. The patient sample ves leprominiques. represented all the primary clinical forms of Acknowledgments. We wish to thank Mr. leprosy. Lepromin derived from the arma­ T. K. M. Nkelele and Miss Edna M. Staple, dillo (lepromin-A) provoked the same pat­ S.R.N., of Kivuvu, who helped perform the skin tern of responses as human derived lepro­ tests and provided administrative assistance, and min (lepromin-H), i.e., lepromatous patients Mr. Mbongi Kiletu Mandiangu, General Director, gave the weakest reactions and tuberculoid Institut Medical Evangelique, Kimpese, for his patients the strongest reactions. Lepro­ support. We are especially grateful to all the lep­ rosy patients who so willingly cooperated after min-A reactions were consistently more being informed of the details of the study. intense than those to lepromin-H. We con­ clude that lepromin-A is a promising alter­ native to lepromin-H and may make the REFERENCES worldwide distribution of a standardized I. ABE, M., YOSH INO, Y., KOBAYAS HI , S. AND ski n testing reagent feasible. HOKIB ARA, H. Studies on the preparation, standardization and preservation of lepromin. RESUMEN VII. Changes in the bacteri a l count and the Para determinar la utilidad del tejido de a rma­ potency of le promin during preservation. dillo infectado con Mycobacterium leprae como Lepro 39 (1970) 1-6. substituto de lepromas humanos para la prepara­ 2. BULLOCK, W. E. Studies of immune mecha­ cidn de lepromina, comparamos las reacciones ni sms in leprosy. I. Depression of delayed al­ de la piel a preparaciones de estos dos materia les lergic response to ski n test antigens. N. Eng\. en 115 enfermos con lepra. La muestra de pacien- J . Med. 278(1968) 298-304. 43, 3 Meyers el al: Comparison of Human and Armadillo Lepromins 225

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