Pemphigoid with antibodies to laminin γ1, BP180 and BP230, associated with psoriasis vulgaris: Successful disease control with cyclosporin

Both anti‐laminin γ1 pemphigoid and bullous pemphigoid are autoimmune subepidermal blistering diseases. The former is rare and characterized by autoantibodies to laminin γ1, a 200‐kDa dermal protein, while the latter is common among the elderly and characterized by autoantibodies to BP180 and BP230, both of which are hemidesmosomal proteins. We experienced a 69‐year‐old Japanese male patient with blister formation secondary to erythrodermic psoriasis, which was successfully treated with cyclosporin. The histopathology of erythema corresponded with psoriasis and that of a blistering lesion showed infiltration of neutrophils and eosinophils in and around the subepidermal blisters. Patient immunoglobulin G antibodies labeled both the epidermal and dermal sides of 1 mol/L NaCl‐split human skin by indirect immunofluorescent microscopy and recognized laminin γ1, BP180 and BP230 by immunoblotting. To the best of our knowledge, this is the first report of coexistence of psoriasis and atypical pemphigoid with these three autoantibodies.     

Possible paraneoplastic syndrome case of bullous pemphigoid with immunoglobulin G anti‐BP180 C‐terminal domain antibodies associated with psoriasis and primary macroglobulinemia

A 61‐year‐old Japanese man developed bullous skin lesions during topical therapy for psoriasis vulgaris. Physical examination demonstrated numerous tense bullae and scaly erythemas on the trunk and extremities. Histopathology of the skin biopsy demonstrated subepidermal bullae and lymphocytic infiltration with eosinophils in the dermis. Direct immunofluorescence revealed linear deposits of immunoglobulin (Ig)G, IgA and C3 along the basement membrane zone. Indirect immunofluorescence of 1 mol/L NaCl‐split skin showed IgG reactivity with both epidermal and the dermal sides. IgM reactivity with both the epidermal and dermal sides was also detected. Enzyme‐linked immunosorbent assays showed negative results for both BP180 and BP230. Immunoelectrophoresis of serum and bone marrow aspiration revealed underlying primary macroglobulinemia with M‐proteinemia of IgM‐κ type. Immunoblot analysis revealed IgG, but not IgM, antibodies to recombinant protein of BP180 C‐terminal domain. We diagnosed the present case as bullous pemphigoid with IgG anti‐BP180 C‐terminal domain autoantibodies associated with primary macroglobulinemia and psoriasis vulgaris. Systemic administration of prednisolone 30 mg/day resulted in dramatic improvement of both bullous and psoriatic skin lesions. When the bullous and psoriatic lesions relapsed, DRC chemotherapy (dexamethasone, rituximab and cyclophosphamide) for macroglobulinemia was performed. Then, the psoriatic lesions improved and the bullous lesions disappeared. We suggested that the present case may be paraneoplastic syndrome of bullous pemphigoid associated with primary macroglobulinemia and psoriasis vulgaris.     

Relapse‐associated autoantibodies to BP180 in a patient with anti‐p200 pemphigoid

Anti‐p200 pemphigoid and bullous pemphigoid (BP) are autoimmune subepidermal blistering diseases characterized by autoantibodies to a 200‐kDa dermal antigen (p200) and two hemidesmosomal proteins (BP180 and BP230), respectively. We report a 70‐year‐old man with haemorrhagic blisters, widespread crusted erosions, and the immunopathological characteristics of anti‐p200 pemphigoid. Treatment with doxycycline, topical corticosteroids and immunoadsorption led to rapid clinical remission. However, 19 weeks later, a relapse occurred with generalized itchy urticarial erythema and tense blisters. At this time, both strong dermal and epidermal IgG staining was detected by indirect immunofluorescence microscopy on salt‐split skin, and autoantibodies against both p200 and the 16th noncollagenous (NC16A) domain of BP180 were found. Interestingly, the relapse was associated not only with the detection of autoantibodies to a second autoantigen (BP180), but also with an altered clinical phenotype. This case was a unique occasion to directly monitor the emergence of intermolecular epitope spreading during the course of an autoimmune bullous disorder.     

Case of pemphigoid with immunoglobulin G antibodies to BP180 C‐terminal domain and laminin‐γ1 (p200) developed after pneumococcal vaccination

Pemphigoid cases have been reported in association with vaccination, including pneumococcal vaccination in infants but not in adults. There are also sporadic reports of pemphigoid diseases involving reactions to multiple autoantigens. We herein report a 75‐year‐old Japanese patient with pemphigoid who had immunoglobulin G antibodies to both the BP180 C‐terminal domain and laminin‐γ1 (p200), which developed 1 day after pneumococcal vaccination.     

Development of a simple enzyme‐linked immunosorbent assay for the detection of autoantibodies in anti‐p200 pemphigoid

Background Anti‐p200 pemphigoid is a subepidermal blistering skin disease characterized by autoantibodies against a 200‐kDa protein (p200) of the dermal–epidermal junction. The laminin γ1 chain has recently been identified as target antigen in this disease and the C‐terminus was described as an immunodominant region of laminin γ1. Diagnosis of anti‐p200 pemphigoid requires detection of serum IgG at the dermal side of 1 mol L^?1 salt‐split skin by indirect immunofluorescence microscopy and labelling of a 200‐kDa protein by Western blotting of dermal extract. However, preparation of dermal extract is not widely available, limiting the possibility of diagnosing this disease to a few laboratories. Objectives To develop a simple, sensitive and specific diagnostic tool for anti‐p200 pemphigoid. Methods Sera from patients with anti‐p200 pemphigoid (n = 35), bullous pemphigoid (BP, n = 101), epidermolysis bullosa acquisita (EBA, n = 10), antilaminin 332 mucous membrane pemphigoid (MMP, n = 14), pemphigus vulgaris (PV, n = 51) and healthy volunteers (HV, n = 131) were tested by a novel enzyme‐linked immunosorbent assay (ELISA) that employed a recombinant monomeric C‐terminal fragment of human laminin γ1 (hLAMC1‐cterm) expressed in Escherichia coli. Results Serum reactivity with hLAMC1‐cterm was detected in sera from 24 of 35 (69%) patients with anti‐p200 pemphigoid, two of 101 (2%) with BP, 0 of 10 with EBA, two of 14 (14%) with anti‐laminin 332 MMP, 0 of 51 with PV, and 0 of 131 HV. Conclusions This novel ELISA will facilitate the diagnosis of anti‐p200 pemphigoid.     

Two cases of subepidermal blistering disease with anti-p200 or 180-kD bullous pemphigoid antigen associated with psoriasis

We describe two patients with psoriasis vulgaris who subsequently developed a subepidermal blistering disease which disclosed IgG and C3 at the basement membrane zone in direct immunofluorescence. The first case was a 75-year-old Japanese man with herpetiform lesions. Histopathology showed neutrophil infiltration. IgG antibodies bound to the dermal side of the salt-split skin. Immunoblot analysis identified a 200-kD antigen in dermal extracts. The second case was a 70-year-old Japanese man. Histopathology showed eosinophil infiltration. IgG antibodies bound to the epidermal side of salt-split skin. Immunoblot analysis identified a 180-kD bullous pemphigoid (BP) antigen in epidermal extracts. We review the clinical and pathological features of psoriatic patients who presented a subepidermal blistering disease in which antigens were detected by immunoblot analysis; i.e., anti-p200 pemphigoid (14 cases) or BP (12 cases). There were few distinct clinical differences between two diseases. However, neutrophils were predominant in anti-p200 pemphigoid, while eosinophils were predominant in BP. After blister formation, ciclosporin was used effectively in addition to systemic steroids in the treatment of anti-p200 pemphigoid. On the other hand, ciclosporin was not used in the treatment of BP with psoriasis.     

Case of epidermolysis bullosa acquisita with concomitant anti‐laminin‐332 antibodies

Subepidermal autoimmune blistering disease including bullous pemphigoid, pemphigoid gestationis, mucous membrane pemphigoid, anti‐laminin‐γ1 pemphigoid, linear immunoglobulin A bullous disease and epidermolysis bullosa acquisita (EBA), are all characterized by direct immunofluorescence microscopy or immunoglobulin deposition on the basement membrane zone. Among them, EBA is a rare acquired subepidermal autoimmune blistering disease of the skin and mucous membranes reactive with type VII collagen, a major component of the epidermal basement membrane zone. Anti‐laminin‐332‐type mucous membrane pemphigoid has pathogenic autoantibodies against laminin‐332, which is a basement membrane heterotrimeric protein composed of α3, β3 and γ2 laminin chains. We describe a 73‐year‐old Japanese man presenting with multiple, annular, tense blisters on the lower legs and oral lesions. Despite the severe clinical manifestations, the disease was successfully controlled by combination therapy of oral prednisolone and mizoribine. This case was confirmed to have autoantibodies to both type VII collagen and laminin‐332 α3 chain by indirect immunofluorescence of 1 mol NaCl‐split normal human skin, various immunoblot analyses and enzyme‐linked immunosorbent assays. This case was a rare case of EBA with concomitant anti‐laminin‐332 antibodies.     

Anti‐p200‐Pemphigoid – Eine neue blasenbildende Autoimmundermatose

Anti‐p200 pemphigoid is an autoimmune skin disease characterized by tense blisters, subepidermal split formation, and mainly neutrophilic inflammatory infiltration of the dermal‐epidermal junction (DEJ). Direct immunofluorescence microscopy of perilesional skin biopsies demonstrates linear deposits of IgG and C3 along the DEJ, while by indirect immunofluorescence microscopy on NaCl‐split human skin, patients' IgG labels the dermal side. The antigenic target of the autoantibodies is a 200 kD protein (p200) of the lower lamina lucida that can be detected in human dermal extracts by immunoblotting. While p200 is thought to be important for cell‐matrix adhesion, its exact identity is unknown. To date, the p200 autoantigen has been demonstrated to be distinct from bullous pemphigoid antigens 180 und 230, laminin 1, 5, and 6, α6β4 integrin, and type VII collagen. Biochemical characterization of the p200 molecule revealed a noncollagenous N‐glycosylated acidic protein with an isoelectric point of approximately 5.5. We provide an overview on pathogenesis, clinical features, diagnosis, and treatment of this unique autoimmune dermatosis.     

Simultaneous occurrence of anti‐BP180 mucous membrane pemphigoid and mucosal‐dominant pemphigus vulgaris

We describe the simultaneous initial coexistence of mucous membrane pemphigoid (MMP) with blepharosynechia and anti‐bullous pemphigoid (BP)180 antibodies and pemphigus vulgaris (PV) with lesions limited to the oral mucosa, with the presence of anti‐desmoglein (Dsg)3 antibodies. A 75‐year‐old woman had severe oropharyngeal erosions and ulcers with blisters, and blepharoconjunctivitis and blepharosynechia of the left eye. Histopathological examination of the oral mucosa found acantholysis. Indirect immunofluorescence revealed IgG antikeratinocyte cell surface antibodies, and ELISA disclosed anti‐Dsg3 antibodies. Immunoblotting found positive reactivity with recombinant proteins of both the BP180‐NC16a domain and the BP180 C‐terminal domain. To our knowledge, the simultaneous initial occurrence of MMP and PV has never been reported previously. We present a rare case of concurrent PV and anti‐BP180 MMP, the diagnosis of which was confirmed by ELISA and immunoblotting assays.     

Psoriasis vulgaris coexistent with epidermolysis bullosa acquisita

Summary Autoimmune bullous diseases, such as bullous pemphigoid or pemphigus vulgaris. occasionally develop in psoriatic patients. In addition, a novel subepidermal bullous disease with autoantibodies against a lower lamina lucida antigen of 200kDa has recently been reported in association with psoriasis. We describe here a patient with psoriasis vulgaris who developed epidermolysis bullosa acquisita (EBA). Direct immunofluorescence revealed linear deposition of IgCl and C3 at the basement membrane zone. The patient's serum bound to the dermal side of salt-split normal human skin. However, immnumohlol analysis demonstrated that the patient's serum reacted with an EBA antigen of 290 kDa. EBA should be included in the list of autoimmune diseases associated with psoriasis vulgaris.     

Basement membrane antibodies in sera of haematopoietic cell recipients are associated with graft‐versus‐host disease

Background Graft‐versus‐host disease (GvHD) occurs frequently after haematopoietic cell transplantation (HCT). Mucocutaneous lesions of GvHD may mimic bullous autoimmune dermatoses, and 10 cases of concurrent GvHD and a bullous autoimmune disease have been reported in the literature. Objective To determine the frequency of circulating antibodies to the cutaneous basement membrane zone (BMZ) in HCT patients with GvHD in comparison with HCT patients without GvHD, psoriasis patients and healthy controls. Subjects and methods We examined 42 patients with chronic GvHD, 18 HCT patients without GvHD, 11 psoriasis patients and 40 healthy controls, prospectively. Sera were tested by indirect immunofluorescence (IIF) on salt‐split skin, NC16a‐ELISA and immunoblot using keratinocyte extracts. Univariate statistical analyses and logistic regression were performed to assess possible correlations of graft and patient characteristics with the presence of BMZ antibodies. Results Circulating basement membrane zone (BMZ) antibodies were detected in 10/42 (24%) GvHD sera by immunoblot, but not in any of the HCT sera from patients without GvHD (0/18; 0%). The antibodies targeted collagen VII, BP230, collagen XVII/BP180 or p200/laminin γ1. Clinically manifest bullous autoimmune dermatoses (bullous pemphigoid or epidermolysis bullosa acquisita) were found in two GvHD patients. 1/11 (9%) psoriasis sera and 1/40 (2.4%) healthy control sera reacted with collagen XVII or BP230, respectively. Conclusions Circulating BMZ antibodies are significantly associated with chronic GvHD in contrast to uncomplicated HCT. Recurrent mucocutaneous lesions in chronic inflammatory skin disorders may liberate antigens, which may lead to production of BMZ antibodies, particularly in the context of GvHD‐mediated reduced self‐tolerance.     

Case of bullous pemphigoid coexisting with anti‐desmoglein autoantibodies

A 79‐year‐old Japanese woman had clinical and histopathological features of bullous pemphigoid, while direct immunofluorescence test revealed C3 and immunoglobulin G depositions in the lower cell surfaces of the epidermis in addition to those in the dermoepidermal junction. Chemiluminescent enzyme immunoassays were positive for desmoglein‐1 and ‐3 antibodies in addition to anti‐BP180 antibodies. In an immunoblotting study, antibodies against both 180‐kDa bullous pemphigoid antigen and 130‐kDa pemphigus vulgaris antigen were detected. Based on these results, bullous pemphigoid coexisting with anti‐desmoglein autoantibodies was diagnosed in this case.     

Refractory bullous pemphigoid leaving numerous milia during recovery

Recovery with milia may occur in bullous pemphigoid (BP), mucous membrane pemphigoid (MMP) and epidermolysis bullosa acquisita (EBA). Scarring commonly occurs in MMP and EBA. Here, we report a 62‐year‐old man patient with BP, who was left with numerous milia during recovery. The patient had immunoglobulin (Ig)G autoantibodies to the recombinant protein of the BP180‐NC16a domain and the soluble 120‐kDa ectodomain of BP180 (linear IgA bullous dermatosis [LAD]‐1). There are cases of BP with IgG autoantibodies to LAD‐1 and/or the recombinant protein of BP180 C‐terminal domain. Extensive milia formation during recovery may be associated with immunological predisposition and/or improper interaction between hemidesmosomes and the extracellular matrix components.     

Linear IgA dermatosis with IgA and IgG autoantibodies to the 180 kDa bullous pemphigoid antigen (BP180): evidence for a distinct subtype

BACKGROUND: Autoantibodies in linear immunoglobulin A (IgA) disease (LAD) are reported to be of IgA class and directed against a 97-120 kDa epidermal antigen. METHODS: We report a 39-year-old woman with clinical features of LAD and with circulating IgA and IgG autoantibodies to the 180 kDa bullous pemphigoid antigen (BP180). RESULTS: Histopathology of lesional skin revealed a subepidermal blister with mixed inflammatory cell infiltrate. Direct immunofluorescence of perilesional skin showed linear deposits of IgA along the dermal-epidermal junction. The antigen specificity of the patient's circulating antibodies was determined by Western blotting and enzyme-linked immunoabsorbent assay (ELISA) using various antigen sources, including cultured human keratinocytes, dermal protein lysates, and purified laminin-5, as well as proteins corresponding to BP180, the 230 kDa bullous pemphigoid antigen (BP230), laminin-5 subunits, and collagen IV alpha1-alpha6 chains. IgA and IgG antibodies in the patient's serum were directed against BP180, and no IgA or IgG reactivity was found against the other skin antigens. CONCLUSIONS: These data provide evidence for the presence of a subtype of LAD with dual IgA and IgG autoimmune response to BP180.     

Non‐paraneoplastic autoimmune subepidermal bullous disease associated with fatal bronchiolitis obliterans

Bronchiolitis obliterans is a small‐airway obstructive lung disease for which immunologically mediated pathogenesis is supposed. Frequent association of bronchiolitis obliterans with paraneoplastic pemphigus is well known, but its association with other autoimmune bullous diseases has not been reported except for a case of anti‐laminin‐332‐type mucous membrane pemphigoid in a patient with chronic graft‐versus‐host disease. We report a case of non‐paraneoplastic autoimmune subepidermal bullous disease associated with fatal bronchiolitis obliterans in a patient without transplantation. Although the patient's serum contained immunoglobulin (Ig)A antibodies to the 180‐kDa bullous pemphigoid antigen/type XVII collagen and IgG antibodies to laminin‐332, diagnosis of either linear IgA bullous dermatosis or mucous membrane pemphigoid could not be made because of the failure to detect linear IgA deposition at the basement membrane zone by direct immunofluorescence and the lack of mucous membrane lesions. Physicians should be aware that autoimmune bullous diseases other than paraneoplastic pemphigus can also associate with this rare but potentially fatal lung disease.     

Acquired skin disease of hemidesmosomes.

The hemidesmosome is a membrane-associated supramolecular dermal epidermal complex linking the cytoskeleton of the basal keratinocyte to structures within the papillary dermis. Different components of this complex have been identified as autoantigens in autoimmune bullous skin diseases. Some of the autoantigens have been characterized at the molecular level. Little is known, however, about the factors that initiate the production of autoantibodies. By histopathology, acquired skin diseases of hemidesmosomes show subepidermal blisters and by direct immunofluorescence, linear deposits of IgG, C3 or IgA at the dermal epidermal junction. Bullous pemphigoid (BP) is the most common acquired disease of hemidesmosomes. Two proteins, BP180 and BP230, have been identified as primary targets of autoantibodies in BP. In addition, pemphigoid/herpes gestationis, lichen planus pemphigoides, cicatricial pemphigoid and linear IgA disease are characterized by an immune response to BP180. Laminin 5 is another well-characterized anchoring filament-lamina densa component of hemidesmosomes. Patients with autoantibodies to laminin 5 show the clinical phenotype of cicatricial pemphigoid. Other acquired skin diseases of the hemidesmosomes reveal autoantibodies to a plectin-like protein, the beta4 subunit of alpha6beta4 integrin, uncein and a not yet characterized 168 kDa protein. Recently, diseases with autoantibodies to 105 and 200 kDa proteins of the lower lamina lucida have been reported. The association of these autoantigens with hemidesmosomes still needs to be demonstrated. Finally, anchoring fibrils associate with the dermal epidermal anchoring complex. The major structural component of anchoring fibrils is type VII collagen, the autoantigen of epidermolysis bullosa acquisita.     

Respective contribution of neutrophil elastase and matrix metalloproteinase 9 in the degradation of BP180 (type XVII collagen) in human bullous pemphigoid.

Bullous pemphigoid is a blistering disorder associated with autoantibodies directed against two components of hemidesmosomes, BP180 and BP230. Autoantibodies to the extracellular collagenous domain of BP180 are thought to play a key role in the pathogenesis of the disease. In a murine model of bullous pemphigoid, neutrophil elastase and 92 kDa gelatinase (matrix metalloproteinase 9) have been implicated in subepidermal blister formation via proteolytic degradation of BP180. In this study we sought to elucidate the contribution of these two enzymes to subepidermal blister formation by assessing the expression, localization, and activity of the two proteases in lesional skin, serum samples, and blister fluids obtained from 17 patients with bullous pemphigoid. The results indicate that (i) neutrophil elastase is found in skin biopsy specimens from bullous pemphigoid lesions and is recovered as active enzyme in blister fluids, and (ii) although proform of matrix metalloproteinase 9 is present in lesional skin, it is present only as proenzyme in blister fluids, which also contain high levels of tissue inhibitor of metalloproteinase-1. Next, the capacity of matrix metalloproteinase 9 and neutrophil elastase to degrade a recombinant protein corresponding to the extracellular collagenous domain of the BP180 was studied. Our data illustrate that (i) recombinant matrix metalloproteinase 9, neutrophil elastase, and blister fluid from bullous pemphigoid patients are all able to hydrolyze recombinant BP180; (ii) the pattern of recombinant BP180 proteolysis with blister fluid was similar to that obtained with neutrophil elastase; and (iii) recombinant BP180 degradation by blister fluid could be inhibited by chloromethylketone, a specific elastase inhibitor, but not by batimastat, a wide spectrum matrix metalloproteinase inhibitor. Our results confirm the importance of neutrophil elastase but not matrix metalloproteinase 9 in the direct cleavage of BP180 autoantigen and subepidermal blister formation in human bullous pemphigoid.     

Subepidermal blistering disease with autoantibodies against a novel dermal 200-kDa antigen

A number of autoimmune subepidermal blistering diseases are characterized by the distinct autoantigens of the cutaneous basement membrane zone. Recently, a few cases with autoantibodies against a novel 200-kDa dermal protein have been reported. We collected nine cases of subepidermal blistering disease with IgG antibodies against this 200-kDa antigen. In this report, we describe the clinical and immunological appearances in these cases. Five cases showed bullous pemphigoid-like features, one case resembled dermatitis herpetiformis, and another case showed mixed features of bullous pemphigoid and linear IgA bullous dermatosis. It was interesting to note that psoriasis coexisted in four cases. By indirect immunofluorescence on 1 M NaCl split skin, IgG antibodies from all sera reacted with the dermal side of the split. By immunoblot analysis, IgG antibodies recognized a 200-kDa protein of dermal extract. IgG affinity-purified antibodies on the 200-kDa immunoblot membrane stained the dermal side of 1 M NaCl split skin. Various examinations suggested that the 200-kDa antigen is not identical to any chains of laminins-1, -5 or -6. This autoimmune subepidermal blistering disease against the dermal 200-kDa protein may form a new distinct entity, which often associates with psoriasis.     

Anti-p200 pemphigoid responding to dapsone

Anti-p200 pemphigoid is a rare autoimmune subepidermal blistering disease. Clinical presentation is similar to standard bullous pemphigoid (BP) but mucous membranes and cephalic lesions are more frequent. Histology and direct immunofluorescence (IF) are identical to BP but indirect IF discloses linear deposits of immunoglobulin G (IgG) on the dermal side of artificial salt-split skin. Specific diagnosis is based on western immunoblotting that shows circulating IgG recognizing a 200-kDa protein localized on the dermal extract. The 200-kDa antigen was recently identified as laminin γ1. Anti-p200 pemphigoid should be considered before all atypical or topical steroid-resistant bullous disease, as well as mucous membranes pemphigoid or epidermolysis bullosa acquisita. Dapsone appears to be the most effective treatment and should be used as the first option in combination with topical steroids. In this report, we describe the case of a patient with a typical clinical and immunopathological anti-p200 pemphigoid, responding to a combination of topical steroids and dapsone.     

Autoantibodies in a subgroup of patients with linear IgA disease react with the NC16A domain of BP1801

Linear IgA disease is an autoimmune subepidermal blistering disease characterized by IgA deposits at the cutaneous basement membrane zone. IgA antibodies from linear IgA disease sera react with antigens of 97 kDa (LABD97) and 120 kDa (LAD-1), both of which appear to be fragments of the extracellular domain of bullous pemphigoid 180 (type XVII collagen). The aim of this study was to determine whether linear IgA disease sera react with the immunodominant region of BP180 (NC16A domain), which is a major target of IgG autoantibodies produced by patients with bullous pemphigoid. Indeed, 11 of 50 linear IgA disease sera were found to contain IgA autoantibodies that recognized a recombinant form of NC16A by immunoblotting. The same sera also reacted with NC16A by enzyme-linked immunosorbent assay. An epitope mapping analysis uncovered four linear IgA disease-associated epitopes located within the 45 amino acid N-terminal stretch of NC16A, all of which were previously identified as antigenic sites targeted by bullous pemphigoid autoantibodies. Eight of the linear IgA disease sera that were reactive with NC16A also recognized LAD-1 secreted by the SCC-25 cell line, and five sera recognized BP180 extracted from keratinocytes. Linear IgA disease sera depleted of reactivity to NC16A by immunoadsorption continued to react with both the LAD-1 antigen and BP180 by immunoblotting and with the basement membrane zone by indirect immunofluorescence microscopy. Our results demonstrate that IgA autoantibodies from a subset of linear IgA disease patients react with the same sites on BP180 that are targeted by IgG autoantibodies in bullous pemphigoid.