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Bullous SLE: A Phenotypically Distinctive but Immunologically Heterogeneous Bullous Disorder W. Ray Gammon and Robert A. Briggaman

Bullous systemic erythematosus (SLE) is a rare blistering disease with a distinctive combination of clinical, histologic and immunopathologic features that together constitute a unique bullous disease phenotype. There appear to be at least two immunologically distinct subtypes of bullous SLE characterized by the presence or absence of circulating and/or tissue- bound basement membrane zone that recognize type VII . The two subtypes are not clearly distinguishable except by indirect and/or direct immunoelectron microscopy. In patients without circulating antibodies, immunoelectron microscopy is required to distinguish between the two subtypes. Patients with autoantibodies to type VII collagen are similar but not identical to patients with acquisita – another bullous disease associated with autoantibodies to type VII collagen. Autoantibodies to type VII collagen in patients with bullous SLE is only one of several lines of evidence that indicate to that protein and susceptibility to SLE are associated phenomena. In addition, there is emerging evidence for an association between epidermolysis bullous acquisita and SLE. There is also evidence that autoantibodies to type VII collagen are pathogenic in bullous SLE (and epidermolysis bullosa acquisita) and that their production is regulated by the class II major histocompatibility complex DR beta 1 allele, 1501 and possibly other DR beta 1 alleles that share a similar sequence of amino acids in the second hypervariable region. J Invest Dermatol 100:28S–34S, 1993

During the past 20 years, there have been reports of a small number of subset of ‘‘bullous SLE patients without BMZ antibodies’’ because the patients with systemic lupus erythematosus (SLE) who developed a antibodies in those patients may be tissue-bound. blistering disorder with a relatively distinctive combination of clinical, Antibodies to type VII collagen are not present in all patients. In some histologic, immunohistologic and immunoelectron microscopic (IEM) cases, circulating antibodies to the BMZ cannot be detected by IIF, and features [1–16]. Those features include a widespread eruption of vesicles the Ig deposits in the upper do not codistribute with type VII and bullae that often respond to treatment with dapsone; dermal- collagen by IEM. We refer to those patients as type II bullous SLE (bullous epidermal separation at the epithelial basement membrane zone (BMZ) SLE-II). With the exception of antibodies to type VII collagen, it is not and acute inflammation similar to that seen in clear that bullous SLE I and II are distinguishable. It is certainly not (DH); a linear, granular, or mixed linear and granular pattern of confirmed that differences in the pattern of Ig deposits by DIF can identify immunoglobulin (Ig) (IgG, IgM, IgA) deposits at the BMZ by direct either type, and it is equally clear that negative IIF does not exclude immunofluorescence (DIF); and Ig deposits in the upper dermis and on bullous SLE-I. Consequently, we believe that in those cases where the lamina densa by IEM. This combination of features is not circulating antibodies to type VII collagen cannot be demonstrated by IIF, characteristic of any other primary bullous disease nor is it generally IEM is required to distinguish between bullous SLE I and II. seen except in patients with SLE. The distinctiveness of the phenotype Several lines of evidence indicate that autoimmunity to type VII and its association with SLE support the view that it is a specific collagen and SLE are associated phenomena and that antibodies to type manifestation of SLE. It is usually referred to as bullous eruption of SLE or, VII collagen may be part of the repertoire of SLE. The simply, bullous SLE. evidence includes (1) antibodies to type VII collagen in bullous SLE; (2) In our experience, most patients with the bullous SLE phenotype and an apparent association between susceptibility to SLE and another linear or mixed linear and granular Ig deposits have autoantibodies to the disease associated with autoimmunity to type VII collagen, epidermolysis BMZ protein, type VII collagen. We refer to those patients as type I bullosa acquisita (EBA); and (3) indications that antibodies to type VII bullous SLE (bullous SLE-I). The antibodies may be circulating and tissue- collagen may be present in LE in the absence of a blistering eruption. bound, or just tissue-bound. In the former case, circulating antibodies Experimental evidence indicates that antibodies to type VII collagen can be detected by indirect immunofluorescence (IIF) but in the latter the may play a role in BMZ inflammation and injury in bullous SLE and EBA, tissue-bound antibodies can only be detected by IEM. Importantly, the but there is much that is unknown about the pathogenesis of these absence of circulating antibodies to type VII collagen does not define a diseases. It is not clear why patients develop autoimmunity to this major BMZ adherence protein, but susceptibility is determined, in part, by genetic factors because patients with bullous SLE-I and epidermolysis Department of , University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA bullosa acquisita (EBA) share some of the same class II MHC genes. Reprint requests to: Dr. W.R. Gammon, Department of Dermatology, CB# 7600, 137 UNC Hospitals, Chapel Hill, NC 27514 THE BULLOUS SLE PHENOTYPE: FEATURES AND Abbreviations: ANA, antinuclear antibody; ARA, American Rheumatism DIAGNOSTIC CRITERIA Association; BMZ, epithelial basement membrane zone; BP, bullous Clinical Features The bullous SLE phenotype is composed of a ; C, complement; DH, dermatitis herpetiformis; DIF, direct characteristic set of clinical, histologic, immunohistologic (DIF), and immunofluorescence microscopy; EBA, epidermolysis bullosa acquisita; IEM, immunoelectron microscopy; Ig, immunoglobulin; IIF, indirect IEM features that develop in a patient who meets the American immunofluorescence microscopy; LE, lupus erythematosus; MHC, major Rheumatism Association’s (ARA) classification criteria for SLE [4,5,13]. histocompatibility complex; SLE, systemic lupus erythematosus Most patients have been young black women, but all ages, races, and

0022-202X/93/$06.00 Copyright & 1993 by The Society for Investigative Dermatology, Inc.

28S VOL. 100, NO. 1, SUPPLEMENT, JANUARY 1993 BULLOUS SYSTEMIC LUPUS ERYTHEMATOSUS 29S

Figure 1. Vesiculobullous on the neck and upper chest in a patient with bullous SLE. both sexes are affected [1–16]. The clinical features include a wide- spread, non-scarring vesiculobullous eruption that may occur on, but is not confined to, sun-exposed skin. Lesions may involve flexural or extensor skin and mucosal surfaces of the mouth and pharynx. A predilection for the upper trunk and supraclavicular sites has been described (Fig 1). usually arise on erythematous (inflamed) skin and erythematous macules and plaques may precede blisters. Blisters Figure 2. Histologic features of early lesions of bullous SLE showing may be large and tense and resemble those of bullous pemphigoid (BP) or (arrows) beneath the BMZ in dermal papillae. A, a patient with small and grouped and resemble those of dermatitis herpetiformis (DH). bullous SLE-I who had antibodies to type VII collagen; B, a patient with Mechanical fragility of the skin and healing with scars and milia, bullous SLE-II who apparently lacked antibodies to type VII collagen. characteristic features of classic EBA, are not features of bullous SLE. Magnification 180. Pruritus is not prominent, but patients may and the itching may be severe. The activity of the blistering disorder may or may not coincide with the activity of the patient’s systemic disease [4], Interestingly, the primary lesions of chronic discoid, subacute, and acute LE appear to be tion, and necrosis of blood vessels are apparent [4]. Dermal is uncommon in bullous SLE. not always present in bullous SLE but may be more common than in DH An important and interesting clinical feature of bullous SLE is that it [4]. Although vasculitis may be present histologically, clinical features of may respond to treatment with dapsone [4,6–8,12–14,16]. The response vasculitis such as necrosis and are absent. Histologic is usually dramatic, with cessation of new lesions within 24–48h after changes characteristic of primary lupus lesions such as epidermal administering the drug, and healing of old lesions within several days. A atrophy, basal vacuolization, thickening of the BMZ, and response may be seen with very small doses (25–0mg/d). Rapid mononuclear cell-predominant inflammation are absent in bullous recurrences may follow cessation of dapsone and rapid remissions may lesions. be achieved after reinstituting the drug. These observations persuasively argue for a therapeutic effect of dapsone. The rapid and complete Immunohistologic Features Immune deposits in the upper dermis and on response observed to relatively small doses of dapsone is reminiscent of the BMZ are a consistent feature of bullous SLE. Occasionally, deposits the response observed in DH. Eventually it is possible to discontinue may also be in upper dermal venules. The deposits have been detected administration of dapsone in bullous SLE without a recurrence of the by DIF in lesional skin in all patients and in clinically normal skin in all blistering eruption; however, DH will rapidly exacerbate after with- but one patient. The composition of the deposits has included all the drawal of dapsone. Not all patients with bullous SLE respond to dapsone; major Ig classes (IgG, IgA, and IgM), and complement (C) proteins. In therefore, non-responsiveness does not exclude the diagnosis. Patients most cases more than one Ig class is present and in many cases all three not responding to dapsone may respond to or combination can be detected. IgG has been universally present, IgA has been detected therapy with prednisone and [2,3,5,9,10,13]. in most patients, and IgM has been found in about half the patients [4,13,14]. Complement proteins are usually present in lesional skin but Histologic Features The histologic features of early blisters have been may be absent in clinically normal skin (personal observation). Unlike one of the most consistent and characteristic features of the disease. DH, patients with bullous SLE may lack IgA deposits at the BMZ; Typically, the histology of an early shows inflammation and however, IgA deposits appear to be more comon in bullous SLE than in dermal-epidermal separation at the BMZ (Fig 2). The is usually SLE patients without blisters [4,13]. intact. The upper dermis is characterized by edema and accumulations of One of the most variable features of bullous SLE is the pattern of neutrophils in dermal papillae similar to those seen in DH [2,4]. In many immune reactant deposition. Two major patterns have been described cases, neutrophils are not confined to the papillae but form a continuous [4,6,8] (Fig 3). In most patients the pattern is either granular (about 60% band of cells that is concentrated in the upper dermis, beneath and on the of cases) or linear (about 40% of cases). In a few cases, it has been BMZ, and in the cavity. Some mononuclear cells and thready or fibrillar. In some cases, there may be a mixed pattern with a are usually present in the infiltrate. Mid and upper dermal blood vessels linear band of homogeneous deposits and scattered granular deposits. may have a perivascular accumulation of mononuclear or polymor- Among patients with a linear pattern, the deposits may be wide and phonuclear cells; and, in some cases, the histologic features of bandlike or relatively thin. Granular IgA deposits confined to dermal necrotizing vasculitis including leukocytoclasis, erythrocyte extravasa- papillae, a characteristic feature of DH, are not a feature of bullous SLE 30S GAMMON AND BRIGGAMAN THE JOURNAL OF INVESTIGATIVE DERMATOLOGY

Figure 4. Direct IgG immunoelectron microscopy of perilesional skin from a patient with bullous SLE. The IgG deposits (D) are located in the upper dermis just beneath the lamina densa/basal lamina (B). The lamina lucida (L); which lies between the keratinocyte plasma membrane and the lamina densa, is free of deposits. Magnification 18,000.

Table I. Tentative Criteria for the Diagnosis of Bullous SLE Figure 3. Direct IgG immunofluorescent microscopy of perilesional skin Type I from three patients with bullous SLE showing different patterns of IgG deposits Clinical: an acquired, widespread, nonscarring vesiculobullous at the BMZ. A, a granular and mixed granular-linear pattern that may be seen eruption in patients with bullous SLE-I and bullous SLE-II; magnification 240. B, Histologic: subepidermal blister and acute, -predominant a wide linear/homogeneous pattern that may be seen in patients with inflammation in the upper dermis bullous SLE-I and bullous SLE-II; magnification 240. C, a very narrow linear band of deposits that may be seen in patients with bullous SLE-I; DIF: IgG±IgA/IgM at the BMZ magnification 400. IIF: ±circulating autoantibodies to type VII collagen-confirmed by IIF on split skin, immunoblotting or immunoprecipitation [4]. Importantly, the clinical and histologic features of the bullous SLE IEM: Ig deposits codistribute with anchoring fibrils/type VII collagen phenotype are similar regardless of the pattern of Ig deposits. IEM studies have shown the Ig deposits are located in the upper dermis beneath the lamina densa, and, in some cases, on the Type II lamina densa [3,4,7,8] (Fig 4). Occasionally, the deposits may be on Clinical: same as above andjust beneath the lamina densa and in the deeper dermis as well. The Histologic: same as above deposits are not in the lamina lucida, and that excludes the possibility the blisters are due to a primary bullous disease, such as BP, that is DIF: same as above associated with antibodies to hemidesmosomal and/or lamina lucida IIF: negative antigens. IEM: Ig deposits do not codistribute with anchoring fibrils/type VII CRITERIA FOR THE BULLOUS SLE PHENOTYPE AND collagen EXCLUSION OF OTHER BULLOUS DISEASES The above clinical, histologic, immunohistologic, and IEM features are generally regarded as characteristic of the bullous SLE phenotype and form the basis for the diagnosis (Table I). Minimal features include (1) a diagnosis of SLE by ARA criteria; (2) an acquired, non-scarring bullous and the problems in differential diagnosis have been noted above and eruption; (3) a subepidermal blister with acute neu-trophilpredominant extensively reviewed [4,22]. The only other primary bullous disease to inflammation in the dermis and at the BMZ; and (4) IgG/IgA/IgM deposits consider is EBA and the relationship between EBA and bullous SLE is in perilesional skin [4,5,13]. The Ig deposits must be on or beneath the discussed below. lamina densa to exclude BP or other primary subepidermal bullous diseases associated with antibodies to hemidesmosomal or lamina lucida AUTOIMMUNITY TO TYPE VII COLLAGEN AND THE antigens. It is important to exclude DH because several of its features BULLOUS SLE PHENOTYPE: BULLOUS SLE-I resemble bullous SLE, and a number of patients with both disorders have In 1985, IgG autoantibodies to the BMZ of stratified squamous been reported [17–21]. Some of those may have been patients with epithelium were reported in patients with bullous SLE [8]. The antibodies bullous SLE [4,22]. The major differences between DH and bullous SLE were initially detected in serum by IIF on substrates of normal human VOL. 100, NO. 1, SUPPLEMENT, JANUARY 1993 BULLOUS SYSTEMIC LUPUS ERYTHEMATOSUS 31S

Figure 6. Western immunoblotting of type VII collagen extracted from human basement membrane. Lane 1 shows molecular weight standards. Lane 2 shows blotting with EBA serum containing high titer antibodies to type VII collagen; the serum is a positive control and shows binding to the 290 kD band of tissue type VII collagen. Lane 3 shows blotting with serum from a patient with bullous SLE (BSLE). That serum also shows binding to a 290 kD band. Lane 4 shows blotting with serum from the Texas rabbit that Nicholes and Gilliam had immunized with human epithelial basement membrane extracts. Those investigators showed the immune rabbit serum contained antibodies that cross-reacted with antibodies from lupus patients against extracts of basement membrane. Lane 5 shows blotting with normal human serum as a negative control. Figure 5. Indirect IgG immunoflurescent microscopy on 1.0 M NaCl-split skin using a 1:10 dilution of serum from a patient with bullous SLE-I. The photomicrograph shows a linear band of IgG on the dermal side of the split these patients also have scattered Ig deposits in the upper dermis that are (lower portion of the photograph) consistent with antibodies to type VII not associated with a specific structure or matrix protein. The latter are collagen. There are also deposits on the nuclei of (upper portion not unlike the deposits described in some SLE patients without a of the photograph) consistent with antinuclear antibodies. Magnification blistering eruption [33–35]. These observations suggest there are patients 240. with bullous SLE-I who have tissue-bound, but not circulating, antibodies to type VII collagen. Furthermore, some of these patients appear to have, in addition to specific BMZ antibodies, the non-specific Ig deposits often skin that had been separated through the BMZ by incubation in 1 M NaCl encountered in SLE. (Fig 5). Direct IEM on perilesional skin from those cases showed the Ig deposits were in the upper dermis beneath and on the lamina densa (see Fig 4). Those IEM findings were consistent with findings previously BULLOUS SLE PHENOTYPE WITHOUT reported in bullous SLE (and SLE as well), and excluded the possibility AUTOANTIBODIES TO TYPE VII COLLAGEN: that the autoantibodies were directed to lamina lucida or hemidesmo- BULLOUS SLE-II somal antigens [3,4,8,10,23,24]. The absence of Ig deposits in the lamina Patients with bullous SLE without circulating autoantibodies to type VII lucida also excluded the possibility the patients had coexistent SLE and collagen have been reported [3–5,13,14]. Most of them were not BP, which had been reported [25–31]. examined by direct IEM; therefore, their status regarding type VII The circulating antibodies from those patients were further character- collagen autoimmunity remains unresolved. However, we know of at ized and found to have immunochemical, immunohistologic, and least one case that was completely evaluated using immunofluorescence immunoultrastructural features that are now known to be characteristic and IEM without finding evidence of autoantibodies to type VII collagen. of antibodies to type VII collagen [32]. Those features included reactivity Briefly, the patient was a 41-year old white woman with SLE diagnosed with 290-kD and 145-kD proteins in extracts of basement on the basis of photosensitivity, arthralgias, a coombs þ hemolytic membrane, binding to the dermal side of split skin, and binding on and anemia, a positive antinuclear antibody (ANA) (titer 1:2560), lymphade- just beneath the lamina densa of normal human skin by indirect IEM [8] nopathy, and nephritis. She had an 8-month history of a recurrent, non- (Figs 4–6). The localization of the cutaneous Ig deposits on and just scarring vesiculo-bullous eruption of the face, upper chest, back, and beneath the lamina densa by direct IEM was also consistent with tissue- extensor extremities. The lesions cleared within 2 d of treatment with bound antibodies to type VII collagen. 50 mg daily of dapsone. The histology of a skin lesion showed a We have also encountered patients in whom IIF studies have been subepidermal blister with neutrophil-predominant, DH-like inflamma- negative, but direct IEM has shown IgG deposits on and just beneath the tion (Fig 2B). DIF of perilesional skin showed a mixed linear and granular lamina densa in a pattern characteristic of antibodies to type VII collagen pattern of IgG, IgA, and IgM deposits at the BMZ (Fig 3B). IIF on NaCl [3]. The deposits in these cases have been indistinguishable from deposits split skin showed no evidence of BMZ antibodies even in undiluted in patients with circulating antibodies to type VII collagen [32]. Some of serum. Direct IEM showed scattered granular deposits of IgG, IgA, and 32S GAMMON AND BRIGGAMAN THE JOURNAL OF INVESTIGATIVE DERMATOLOGY

collagen. They also appear to share similar genetic features (see below). Additional evidence supporting a relationship includes the fact that the clinical and pathologic features characteristic of bullous SLE may occasionally occur in EBA. For example, EBA may present with a widespread non-scarring bullous eruption without mechanical fragility and with a DH-like histology [40]. In addition EBA, like bullous SLE, may be associated with SLE (see below); and patients with the bullous SLE phenotype may evolve an EBA phenotype ([41], personal observation). Nevertheless, there appear to be differences between the characteristic features of the disorders and some of those differences are clinically significant. Unlike bullous SLE, EBA is often associated with skin fragility and healing of lesions with scars and milia. The DH-like histology that is typical of bullous SLE is seldom seen in EBA. Whereas EBA usually begins Figure 7. IgG direct immunoelectron microscopy (magnification 15,000) in the fourth and fifth decades, bullous SLE usually begins in the second comparing the pattern of IgG deposits at the BMZ in A, a patient with bullous and third decades. EBA often lasts for many years whereas bullous SLE-I who has antibodies to type VII collagen and B, a patient with bullous SLE is remitting and often resolves spontaneously in less than a year. SLE-II who apparently does not have those antibodies. A shows deposits on Interestingly and perhaps most importantly, EBA only rarely, if ever, and just beneath the lamina densa and codistributing with type VII collagen. responds to treatment with dapsone. Similar deposits can also be seen in Fig 4. B shows deposits (D) in the upper dermis but well beneath the lamina densa. The deposits do not codistribute RELATIONSHIP BETWEEN SLE AND with anchoring fibrils (arrows), which are distinctly separate from the AUTOIMMUNITY TO TYPE VII COLLAGEN deposits. Several lines of evidence strongly suggest an association between susceptibility to LE and autoimmunity to type VII collagen and that autoantibodies to type VII collagen are part of the autoantibody repertoire IgM in the upper dermis but no deposits were observed on or just beneath of some patients with LE. One piece of evidence is that autoantibodies to the lamina densa where type VII collagen is located (Fig 7). Anchoring type VII collagen are present in bullous SLE. Another is the apparent fibrils, which are composed primarily of type VII collagen, were clearly association between SLE and EBA. Patients have been described with visible in the immunoelectron micrographs and were not associated with concurrent SLE and EBA, SLE followed by EBA, and EBA followed by SLE Ig deposits. This patient clearly had the features of the bullous SLE [41–43]. Of over 60 patients we have seen with autoimmunity to type VII phenotype but did not have evidence of antibodies to type VII collagen. collagen, approximately 30% have, have had, or develop SLE, which can hardly be viewed as a coincidental association given the relative DISTINGUISHING BETWEEN infrequency of the conditions. BULLOUS SLE TYPES I AND II Not all patients with SLE and autoantibodies to type VII collagen have a blistering disease. We have documented at least one patient who had Evaluating patients with bullous SLE for autoantibodies to type VII SLE by ARA criteria and circulating and tissue-bound antibodies to type collagen is not easy. Even in cases with circulating antibodies, routine IIF VII collagen documented by IIF on split skin, IEM, and immunoblotting using epithelial substrates with an intact BMZ may give negative results studies [8]. That patient had a circulating, low-titer IgG BMZ autoanti- [8,16]. The antibodies are usually low titer (o1:10 to 1:40), and there body in serum that bound exclusively to the dermal side of split skin. By may be interference from anti-nuclear antibodies. The most sensitive direct IEM, there were IgG deposits codistributing with type VII collagen substrate in our experience is NaCl-split normal human skin [36]. The and Western immunoblotting showed a serum antibody that reacted with substrate also distinguishes between autoantibodies to type VII collagen 290- and 145-kD bands in extracts of human BMZ. The patient had no and autoantibodies to hemidesmosomal and lamina lucida antigens. In history of a blistering eruption, and never developed blisters during an patients without circulating antibodies, IEM studies, which are expensive 8-year follow-up. That is the only patient we have encountered with SLE and not always easy to obtain, are required to demonstrate Ig deposits without a blistering eruption in whom we have found direct evidence for codistributing with type VII collagen. Unfortunately, the great majority of autoantibodies to type VII collagen. We have not found the antibodies patients reported as ‘‘bullous SLE without BMZ autoantibodies’’ have among 30 additional SLE patients using IIF on split skin. However, those only been evaluated by IIF and usually by standard IIF rather than IIF on studies do not exclude the possibilities of tissue-bound antibodies split skin. without circulating antibodies, as in some patients with EBA and bullous To our knowledge, patients with and without antibodies to type VII SLE, or that circulating antibodies are present in insufficient concentra- collagen are indistinguishable with the possible exception that the latter tion to be detected by IIF. may be more likely to have a granular or mixed granular-linear pattern of There are also several indirect lines of evidence suggesting antibodies Ig deposits. However, very few patients with a granular pattern have been to type VII collagen may be present in LE patients without a blistering examined by IEM, and some of them may have tissue-bound BMZ eruption. One is the IEM features of cutaneous Ig deposits in SLE patients antibodies. This possibility is suggested by reports of eluting BMZ without a blistering eruption. Several studies have reported and shown autoantibodies from the skin of SLE patients with granular deposits at the illustrations of IgG deposits that are indistinguishable from the deposits in BMZ [37–39]. It is clear that patients with the bullous SLE phenotype may EBA and bullous SLE patients with antibodies to type VII collagen have antibodies to type VII collagen, that those antibodies may only be [23,24]. present in tissue, and that the only reliable way to detect tissue-bound Additional evidence for BMZ autoantibodies in SLE comes from a antibodies (or exclude them) is IEM. group of three studies, which collectively investigated the specificity of antibodies in eluates of cutaneous Ig deposits in several SLE patients RELATIONSHIP BETWEEN BULLOUS SLE-I AND EBA [37–39]. The results showed most of those eluates contained IgG The relationship between bullous SLE-I and EBA is an interesting question antibodies that reacted with the BMZ of normal human skin. The that has not been satisfactorily resolved. Clearly, they are closely related specificity of those antibodies has not been determined but the studies disorders because both are chronic acquired bullous diseases characte- suggest elution of tissue-bound Ig might be a reasonable approach to rized histologically by inflammatory subepidermal blisters and immuno- investigate a possible association between autoanti-bodies to type VII logically by circulating and tissue-bound autoantibodies to type VII collagen and SLE. VOL. 100, NO. 1, SUPPLEMENT, JANUARY 1993 BULLOUS SYSTEMIC LUPUS ERYTHEMATOSUS 33S

Additional evidence for BMZ autoantibodies (some of which to result, at least in part, from inflammatory injury to the BMZ; however, may have anti-type VII collagen specificity) comes from studies by the the cause of inflammation is not established and may be different in late Dr. James N. Gilliam and his co-worker, Dr. Brenda Nicholes patients with and without antibodies to type VII collagen. There are [44,45]. They tested sera from a number of SLE patients and controls several reasons to believe that BMZ immune deposits may play a role in for antibodies to antigens in extracts of normal human skin BMZ using both subsets. First, all patients have the deposits in perilesional skin. a sensitive counter immunoelectrophoresis assay. They found that 30 Second, the deposits are located in the upper dermis on and just beneath percent of LE patients, but no controls, had antibodies to the extracts. the lamina densa, which corresponds precisely to the ultrastructural Rabbits immunized with the extracts produced antibodies that location of BMZ separation. Third, it appears that the site of separation in reacted to a lamina densa antigen in normal human skin. Gilliam and the BMZ is specifically targeted for inflammatory injury because it is Nicholes found that immune rabbit serum and serum from one of the SLE normally the strongest region of epidermal-dermal adherence and the patients had antibodies that cross-reacted with human BMZ antigens. most resistant to separation. The immune deposits are strategically Shortly before his death, Dr. Gilliam sent immune rabbit serum to one located to initiate and target that inflammation and currently no other of us (WRG), and analysis of that serum by IIF on split skin and candidates are known. Fourth, there is evidence the deposits may be able immunoblotting against extracts of human BMZ showed it contained to initiate inflammation. Studies have shown they are able to activate the antibodies to human type VII collagen (Fig 6). The observations made by C-system and mediate C-dependent migration and adherence of Gilliam and Nicholes clearly raise the possibility that BMZ antibodies leukocytes to the BMZ. Furthermore, cutaneous immune deposits in may not be rare in SLE, and that they may, in some cases, react with type the perilesional skin of patients with bullous SLE activate C and generate VII collagen. C-derived inflammatory mediators to a significantly greater degree than the deposits in uninvolved skin from the same patients or the deposits in SLE patients without blisters [6]. GENETIC REGULATION OF AUTOIMMUNITY There is indirect evidence supporting a specific role for auto- TO TYPE VII COLLAGEN IN BULLOUS SLE-I antibodies to type VII collagen in initiating and targeting inflam- During the past several years, we have been investigating an association mation at the BMZ in bullous SLE-1. For example, in vitro studies have between major histocompatibility complex (MHC) genes and autoimmu- shown the antibodies are capable of activating C and generating nity to type VII collagen. In an initial study, we typed class I and class II C-derived peptides that can mediate leukocyte activation, migration, MHC antigens in a large number of white and black EBA patients and a and adherence to the BMZ [51,52]. In addition, they can cause BMZ small number (6) of black patients with bullous SLE-I [46]. The results of disruption and dermal-epidermal separation following passive transfer those studies showed a significant association between the class II in human skin organ culture. Monoclonal antibodies to type VII collagen antigen, DR2, and EBA in both white and black patients. Furthermore, we have been shown to cause inflammation at the BMZ following found that five of six patients with bullous SLE were DR2 positive. We passive transfer in rabbits [53]. Additional indirect evidence comes from have recently completed class II MHC typing on an additional 12 patients studies showing EBA patients with acute inflammation have significantly with bullous SLE and found a 76% incidence of DR2 among the higher levels of circulating and tissue-bound C-activating antibodies combined 18 patients, which is significantly greater than the incidence of to type VII collagen than EBA patients with chronic or minimal DR2 in geographic and race-matched controls. It seems unlikely that the inflammation [54]. DR2 association is due to an independent association with SLE because all but 1 of the 18 patients is black and studies of blacks with SLE have REFERENCES failed to demonstrate an association with DR2 [47–49]. We have recently sequenced the hypervariable region of the DR beta 1 gene from several 1. 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