Linear IgA Bullous Dermatosis with Circulating IgG Autoantibodies to the 230 kD Epidermal Antigen

The patient was a 54-year-old woman with wide-spread bullous lesions on her trunk and oral mucosa. Histologic examination revealed a subepidermal blister with infiltration of neutrophils and eosinophils. Direct immunofluorescence showed an exclusively IgA deposition at the basement membrane zone (BMZ). Indirect immunofluorescence showed that the blister fluid, but not the serum, contained IgG antibodies against the BMZ antigen on the epidermal side of salt-split skin. Using immunoblot analysis with normal human epidermal extracts, both serum and blister fluid reacted with the 230 kD epidermal antigen. Using colloidal gold and direct immunoelectron microscopy, IgA deposition was detected in the lamina lucida. Clinically, the skin lesions responded well to dapsone. We diagnosed this case as linear IgA bullous dermatosis (LABD) with IgG class circulating autoantibodies against the epidermal 230 kD antigen. These antibodies were considered to be secondary to the damage to the epidermal basal keratinocyte in this case.     

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.     

Coexistence of psoriasis and an unusual IgG-mediated subepidermal bullous dermatosis: identification of a novel 200-kDa lower lamina lucida target antigen

Summary Bullous pemphigoid (BP) is characterized by autoantibodies against 230- and 180-kDa hemidesmosomal antigens located in the most superficial layers of the basement membrane zone (BMZ). Histologically. there is a predominance of eosinophils in the infiltrate. In a psoriatic patient, we identified an unusual autoimmune subepidermal bullous eruption which clinically resembled BP, but which was characterized by IgG autoantibodies against a novel 200-kDa lower lamina lucida component, Histologically there was a predominance of neutrophils in the infiltrate.
Direct immunofluorescence showed linear immunoglobulin (Ig)G and C3 deposition at the BMZ. The patient's IgG autoantibodies bound exclusively to the dermal side of salt-split normal human skin. Indirect immunogold electron microscopy showed a marked deposition of IgG at the lower lamina lucida and minimal deposition at the hemidesmosomes. Immunoblot analysis identified a unique 200-kDa autoantigen in dermal extracts and a faint band of the 230-kDa BP antigen in epidermal extracts. The patient responded dramatically well to cyclosporin A.
Although the patient's serum also reacted slightly with the 230-kDa BP antigen, there were significant findings different from the usual immunopathological changes of BP. These included finding a novel 200-kDa lower lamina lucida target antigen, the binding of IgG autoantibodies exclusively to the dermal side of the split skin and a predominance of neutrophils in blister infiltrate. The IgG autoantibodies against the 200-kDa lamina lucida target antigen seemed to play a major role in the pathogenesis of this unique autoimmune subepidermal dermatosis.     

A case of mixed bullous disease of epidermolysis bullosa acquisita and linear IgA bullous dermatosis

A 75-year-old Japanese male visited us with bullous eruptions on the extremities. Physical examination revealed large bullae on the hands, lower legs and feet. The oral mucosa was also involved. Histology disclosed subepidermal blister with inflammatory cell infiltrates in the dermis. Direct immunofluorescence showed deposits of IgG and IgA at the cutaneous basement membrane zone. Indirect immunofluorescence on 1 M NaCl-split human skin sections demonstrated that the patient's IgG antibodies reacted with the dermal side of the split, while IgA antibodies reacted with the epidermal side. Immunoblotting showed that the patient's serum reacted with the NC1 domain of type VII collagen (290-kDa epidermolysis bullosa acquisita antigen) as well as the 120-kDa linear IgA bullous dermatosis antigen, LAD-1. Systemic prednisolone resulted in a favorable response. From the clinicopathological findings, the present case is not consistent with either epidermolysis bullosa acquisita or IgA bullous dermatosis. Therefore, we regarded the case as mixed bullous disease of epidermolysis bullosa acquisita and linear IgA bullous dermatosis. Such a case has not been previously reported.     

Two Cases of Atypical Bullous Disease Showing Linear IgG and IgA Deposition in the Basement Membrane Zone

Patients showing coexistent linear IgG and IgA deposition along the basement membrane zone on direct immunofluorescence have been described as either bullous pemphigoid, epidermolysis bullosa acquisita, linear IgA bullous dermatosis, or cicatricial pemphigoid, depending on the clinical features and laboratory findings. In the present report, we describe two cases showing atypical clinical features distinct from those of other known bullous diseases. No circulating antibodies were detected by indirect immunofluorescence of normal human skin. Indirect immunofluorescence of 1 M NaCl split skin revealed IgG and/or IgA antibodies reactive with the dermal side of the split. Immunoblotting of normal human epidermal and dermal extracts showed no apparent reactivity with known autoantigens. The results suggest that there may be a unique and distinct bullous disease with linear IgG and IgA deposition at the basement membrane zone.     

Coexistence of psoriasis and linear IgA bullous dermatosis

Linear IgA bullous dermatosis (LABD) is characterized by IgA autoantibodies against components of the basement membrane zone (BMZ). A 97-kDa protein is one of the major autoantigens associated with this disease. We report a 68-year-old man who developed LABD after a 3-year history of psoriasis and in the context of active hepatitis C virus infection. He had been treated with cyclosporin for psoriasis for about 9 months. Histologically, there was a subepidermal blister containing neutrophils and eosinophils with lymphocytes infiltrating predominantly in the dermis. Direct immunofluorescent staining showed linear IgA deposition at the BMZ. The patient's IgA autoantibodies bound exclusively to the epidermal side of 1 mol/L salt-split normal human skin. Immunoblot analysis identified a 97-kDa autoantigen in epidermal extracts. This appears to be the first case of LABD with IgA autoantibodies against a 97-kDa autoantigen, associated with psoriasis and hepatitis C virus infection.     

Linear immunoglobulin A/G bullous dermatosis associated with ulcerative colitis

Linear immunoglobulin (Ig)A/G bullous dermatosis (LAGBD) is an autoimmune bullous disease characterized by formation of subepidermal blisters and linear deposition of IgA and IgG antibodies along the basement membrane zone (BMZ). The association between linear IgA bullous dermatosis and ulcerative colitis (UC) is well recognized, but reports of UC‐associated LAGBD are lacking. We have reported a 24‐year‐old man suffering from LAGBD associated with UC, which occurred before exacerbations of skin rash. A skin biopsy indicated a subepidermal blister with an infiltration of primarily neutrophils and eosinophils in the dermis. Direct immunofluorescence (IF) studies showed a linear deposition of IgA, IgG and C3c. Indirect IF of human skin revealed IgA and IgG anti‐BMZ autoantibodies. Indirect IF of 1 M NaCl‐split human skin demonstrated reactivity of IgA and IgG antibodies at the epidermal side. Immunoblotting showed that IgG antibodies reacted to the BP180 NC16a domain and 120‐kDa linear IgA dermatosis‐1, and enzyme‐linked immunoassay detected IgG anti‐BP230 antibodies. Administration of prednisolone and diaminodiphenyl sulfone (DDS) via the p.o. route improved skin lesions and bowel conditions. These results suggest that the bowel inflammation observed in UC may have a causative effect of initiation of the immune response to the skin and development of the bullous skin lesions in LAGBD. A combination of DDS and corticosteroid could be a recommended therapeutic option for patients with LAGBD with UC.     

Linear IgA disease with IgA antibodies directed against 200- and 280-kDa epidermal antigens

We report an 80-year-old man with the lamina lucida type of linear IgA disease, with IgA autoantibodies reactive with 200-kDa and 280-kDa epidermal proteins. The patient presented with widespread bullous lesions on his trunk and extremities without mucosal involvement. Histopathology of lesional skin showed a subepidermal blister with papillary microabscesses of neutrophils and a few eosinophils. Direct immunofluorescence microscopy of perilesional skin showed linear deposits of IgA and C3 at the basement membrane zone. The patient's serum contained IgA autoantibodies that bound exclusively to the epidermal side of 1 mol L-1 NaCl split skin as determined by indirect immunofluorescence microscopy. Circulating IgA autoantibodies to 200- and 280-kDa antigens were detected in the patient's serum by immunoblot analysis using extracts from normal human epidermis and human epidermal keratinocytes. These two antibodies, eluted from individual nitrocellulose membranes, reacted with the epidermal side of 1 mol L-1 NaCl split skin on indirect immunofluorescence microscopy, and bound to hemidesmosomes as determined by immunoperoxidase electron microscopy. This observation suggests the presence of hitherto uncharacterized 200- and 280-kDa hemidesmosomal proteins distinct from BPAG1, BPAG2 and beta4 integrin as target antigens in linear IgA disease.     

Localized linear IgA/IgG bullous dermatosis

Linear IgA/IgG bullous dermatosis (LAGBD) is an auto-immune blistering disease characterized by the local accumulation of IgA- and IgG-class anti-basement membrane autoantibodies. It typically presents as a generalized pruritic vesiculobullous eruption. No cases of localized LAGBD have yet been reported. We report a case of a 78-year-old man with LAGBD localized to the perianal area. The patient complained of suffering from persistent ulcers around the anus for more than 3 years. Physical examination revealed several blisters and ulcers up to 2-cm in diameter around the anus. No lesions were found elsewhere on the body. Histological analysis of a skin biopsy revealed subepidermal blistering, while direct immunofluorescence showed the linear deposition of IgA and IgG antibodies at the dermoepidermal junction. Indirect immunofluorescence of normal human skin whose layers had been separated using 1M NaCl showed the binding of both IgA and IgG to the epidermal side. Immunoblotting demonstrated the presence of circulating IgA and IgG autoantibodies that bound to a 120-kDa protein. This is the first case of localized LAGBD whose skin lesions were restricted to the perianal region.     

Case of pemphigus with immunoglobulin G and A antibodies,binding to both the intercellular spaces and basement membrane zone

We report a case involving a 62‐year‐old woman with in vivo‐bound immunoglobulin (Ig)G and IgA antibodies in both the intercellular space (ICS) and basement membrane zone (BMZ). Her clinical and histopathological features were identical with those of pemphigus vulgaris, while the immunopathological findings suggested IgG/IgA pemphigus. Direct immunofluorescence (IF) showed in vivo‐bound IgG and IgA antibodies in the ICS and BMZ, whereas indirect IF showed circulating IgG but not IgA antibodies in the ICS and BMZ. The anti‐ICS IgG bound to desmoglein‐3, while the anti‐BMZ antibodies bound to the epidermal side of 1 mol/L NaCl‐split skin. To the best of our knowledge, only two similar cases have been reported so far. Furthermore, we also examined IgG subclass distribution of the in vivo‐bound and circulating anti‐ICS and BMZ antibodies, and found that IgG1, IgG2 and IgG4 bound to ICS of the lesional skins, while IgG1 and IgG3 bound to the BMZ. The circulating anti‐ICS antibodies belonged to IgG1 and IgG4, while the circulating anti‐BMZ antibodies to IgG1, IgG2 and IgG4. We report a case involving a 62‐year‐old woman with in vivo‐bound immunoglobulin (Ig)G and IgA antibodies in both the intercellular space (ICS) and basement membrane zone (BMZ). Her clinical and histopathological features were identical with those of pemphigus vulgaris, while the immunopathological findings suggested IgG/IgA pemphigus. Direct immunofluorescence (IF) showed in vivo‐bound IgG and IgA antibodies in the ICS and BMZ, whereas indirect IF showed circulating IgG but not IgA antibodies in the ICS and BMZ. The anti‐ICS IgG bound to desmoglein‐3, while the anti‐BMZ antibodies bound to the epidermal side of 1 mol/L NaCl‐split skin. To the best of our knowledge, only two similar cases have been reported so far. Furthermore, we also examined IgG subclass distribution of the in vivo‐bound and circulating anti‐ICS and BMZ antibodies, and found that IgG1, IgG2 and IgG4 bound to ICS of the lesional skins, while IgG1 and IgG3 bound to the BMZ. The circulating anti‐ICS antibodies belonged to IgG1 and IgG4, while the circulating anti‐BMZ antibodies to IgG1, IgG2 and IgG4.     

Cutaneous IgA deposits in bullous diseases function as ligands to mediate adherence of activated neutrophils

Linear IgA bullous dermatosis and dermatitis herpetiformis are inflammatory subepidermal blistering diseases characterized by IgA deposits at the cutaneous epithelial basement membrane and in dermal papillae, respectively. Inflammation in both disorders localizes to sites of IgA deposition and is characterized by a predominance of neutrophils. From these observations we postulate that IgA deposits in both diseases may contribute to the recruitment and/or localization of neutrophils. In this study we examined the ability of in vitro and in vivo bound IgA anti-basement membrane autoantibodies from patients with linear IgA bullous dermatosis and in vivo bound IgA deposits in dermal papillae from patients with dermatitis herpetiformis to mediate adherence of neutrophils stimulated by granulocyte macrophage colony-stimulating factor. The study showed that stimulated neutrophils adhered to basement membranes and dermal papillae containing IgA deposits. Adherence was IgA anti-basement membrane antibody concentration dependent and correlated with the immunofluorescence staining intensity of IgA deposits in dermal papillae. Adherence to IgA deposits but not IgG deposits could be inhibited by purified exogenous secretory IgA but not IgG and adherence to IgG deposits could be inhibited by purified exogenous IgG but not secretory IgA. These results provide direct experimental evidence that cutaneous IgA deposits in linear IgA bullous dermatosis and dermatitis herpetiformis can function as ligands for neutrophil adherence and have a role in the localization of inflammation in these disorders.     

The predominance of IgG4 in prodromal bullous pemphigoid

Background Prodromal bullous pemphigoid (PBP) and bullous pemphigoid (BP) demonstrate immunoglobulin G (IgG) and/or C3 deposition at the basement membrane zone (BMZ) on direct immunofluorescence. BP‐180‐specific IgG1, IgG4, and IgE antibodies have been detected in BP. However, the distribution of IgG subclasses is unknown in PBP. Objectives We will describe the role of anti‐BMZ IgG subclasses in PBP and we will correlate these findings to better understand the pathogenesis of PBP. Methods Skin biopsies and serum samples were obtained from 45 patients who had PBP. The skin tissue was processed for direct immunofluorescence studies. Sera were analyzed by indirect immunofluorescence for the presence of circulating anti‐BMZ IgG antibodies (by standard IIF) and IgG subclasses antibodies (by sandwich double antibody immunofluorescence [SDAI]). Sera were also analyzed for antibodies against BP‐180 and BP‐230 antigens by enzyme‐linked immunosorbent assay (ELISA). Results Thirty‐two patients (71%) had IgG and C3 staining at the BMZ, while 13 patients (29%) had isolated C3 staining at the BMZ on direct immunofluorescence. All patients demonstrated staining on the epidermal side of the salt‐split skin. Of the seven skin specimens that were available for C5‐9 SDAI testing, all were found to be positive along BMZ area. Standard IIF studies demonstrated the presence of circulating BMZ antibodies in 11 of the 30 patients (36.6%). When SDAI for IgG subclass differentiation was utilized, 17 of 30 (56.6%) patients were found to have circulating anti‐BMZ antibodies. All of these 17 patients had IgG4 subclass antibodies. Thirteen patients did not have detectable IgG subclass anti‐BMZ antibody on SDAI. Sixteen of 30 patients had detectable anti‐BP‐180 or anti‐BP‐230 antibodies, while 12 (40%) did not have detectable antibody against BP antigens on ELISA. Conclusions IgG4 is the initial and predominant anti‐BMZ antibody subclass detected in PBP. Demonstration of linear C5‐9 at the BMZ enhances the early diagnosis of PBP. Predominance of IgG4 and the initial presence of IgG4 on skin lesions as well as the presence of only IgG4 subclass anti‐BMZ antibody suggest that IgG4 subclass antibody could be the initial immunologic event encountered in patients with PBP.     

IgA antibodies recognizing LABD97 are predominantly IgA1 subclass.

Linear IgA bullous dermatosis is a rare acquired subepidermal blistering disease of the skin. A recognized antigen in linear IgA bullous dermatosis is a 97-kDa basement membrane zone protein termed LABD97. Previous studies, using immunofluorescent techniques, have suggested that the IgA response is restricted to the IgA1 subclass. We studied the IgA antibody subclasses in the sera of 6 patients that contained circulating IgA antibodies reactive with LABD97. The methods used included direct and indirect immunofluorescence and Western immunoblot. All patients tested had IgA1 anti-LABD97 antibodies detected by all 3 methods. Two patients had IgA2 antibodies detected by direct immunofluorescence. Three patients had IgA2 antibodies on indirect immunofluorescence. Two of these also had anti-LABD97 IgA2 antibodies and 1 had secretory component containing anti-LABD IgA antibodies on Western immunoblot. We conclude that the predominant IgA antibody subclass reactive with LABD97 in LABD is IgA1, although the IgA2 subclass may be involved in some cases.     

Use of 1M NaCl split skin in the indirect immunofluorescence of the linear IgA bullous dermatoses

We compared 1M NaCl split skin with intact skin as substrates for detection of circulating IgA anti-basement membrane (BMZ) antibodies in linear IgA dermatosis (LAD). The sera of 63 patients with LAD including 27 adults and 36 with chronic bullous dermatosis of childhood (CBDC) were examined. 62% of patients overall had circulating IgA anti-BMZ antibodies detectable on intact skin. 73% of patients had circulating antibodies detectable on lM NaCl split skin as an additional 7 sera were positive. This was a statistically significant increase (p<0.01). The sera were mostly positive at a higher titre on the split skin when compared with intact skin. On routine indirect immunofluorescence (IIF) all positive sera produced linear fluorescence on the epidermal side of the split. Twenty serum samples were incubated with split skin overnight; 4 of these specimens exhibited linear fluorescence on the epidermal and dermal sides of the split after this prolonged incubation. These findings suggest that 1M NaCl split skin is a more sensitive substrate for detection of circulating IgA anti-BMZ antibodies in LAD, that these antibodies are heterogeneous and that the target antigen has an epidermal component.     

IgA linear dermatosis (author's transl)]

Besides the typical forms of dermatitis herpetiformis (DH) and bullous pemphigoid (BP) of adults and children, there are cases combining clinical, histological and electronmicroscopic features of both. Linear continuous IgA deposits along basement membrane zone (BMZ) are a most characteristic finding. They differ from the granular IgA deposits in DH, even if these are also distributed along the BMZ (however, preserving as a rule their granular pattern). IgG circulating anti-BMZ antibodies are absent, whereas in some cases IgA anti-BMZ antibodies may be found. In contrast to DH, there is no gluten-sensitive enteropathy, and the gluten-free diet is ineffective. The recognition of this bullous disease as a distinct entity is of practical significance because these cases respond well to combined treatment with sulfones and corticosteroids, all in small doses. Because of diagnostic importance of linear IgA deposits at BMZ we have proposed the name IgA linear dermatosis. In children a counterpart of IgA linear dermatosis of adults is chronic bullous disease of childhood (CBDC), which we propose to call IgA linear dermatosis of childhood.     

IgA-mediated epidermolysis bullosa acquisita: two cases and review of the literature

We describe 2 adult patients with a subepidermal bullous dermatosis with exclusively linear IgA depositions along the epidermal basement membrane zone that were deposited in the sublamina densa zone as witnessed by direct immunoelectron microscopy. Indirect immunofluorescence microscopy of patients' sera revealed circulating IgA autoantibodies that bound exclusively to the dermal site of salt-split skin substrate. Immunoblot analysis using dermal and keratinocyte extracts were negative. Indirect immunofluorescence microscopy using type VII collagen-deficient skin ("knockout" substrate) showed no IgA binding, whereas linear IgA binding was seen at the epidermal basement membrane zone in normal human skin. The autoantigen in the patients was thus type VII collagen. A diagnosis of IgA-mediated epidermolysis bullosa acquisita (IgA-EBA) was made. We systematically reviewed the literature of this subset of patients with linear IgA dermatosis on the basis of the following criteria: exclusive binding of serum-IgA to the dermal side of salt-split skin or IgA depositions in the sublamina densa zone by indirect or direct immunoelectron microscopy. We learned that IgA-EBA is clinically indistinguishable from the classic "lamina-lucida type" linear IgA dermatosis or from the inflammatory type of IgG-mediated epidermolysis bullosa acquisita (IgG-EBA). Only a minority of the patients with IgA-EBA showed milia or scarring or had therapy-resistant ocular symptoms as in the mechanobullous type of IgG-EBA. Most patients with IgA-EBA responded to dapsone therapy.     

Absence of specific histologic changes in guinea pig skin treated with bullous pemphigoid antibodies

Previous studies have reported that intradermal injections of bullous pemphigoid antibodies into guinea pigs can reproduce the histologic and immunohistologic features of bullous pemphigoid lesions. In this study we examined this model to determine its reproducibility and suitability for testing other types of anti-BMZ antibodies. Twenty guinea pigs were injected intradermally with 0.1, 0.3, or 0.5 ml of either bullous pemphigoid serum or IgG fraction containing high-titer complement-binding anti-BMZ antibodies or an equivalent volume of normal human serum or IgG fraction as control. Sites were biopsied at intervals after injection and were examined by routine histology and direct immunofluorescence. The results showed (a) no difference in the incidence of dermal epidermal separation or type of inflammation in experimental and control sites; (b) no evidence of an eosinophil-rich inflammatory reaction typical of bullous pemphigoid; (c) an absence of linear BMZ deposits of IgG and complement in the majority of sites injected with bullous pemphigoid antibodies; and (d) no correlation between dermal-epidermal separation and deposition of immune reactants at the BMZ. These results suggest the histologic changes seen in guinea pigs that are administered intradermal injections of bullous pemphigoid antibodies are nonspecific and that the model is not suitable for testing the pathogenicity of anti-BMZ antibodies in sera or IgG fractions.     

Linear IgA dermatosis: Report of an infantile case and analysis of 213 cases in Japan

A 3‐year‐old boy presented with multiple vesicles, showing a rosette‐like arrangement around the crusts. Histopathological and immunohistochemical examinations demonstrated subepidermal blistering with neutrophilic infiltration associated with deposition of IgA, but not IgG, linearly distributed along the basement membrane zone (BMZ) of the epidermis. Indirect immunofluorescence revealed circulating antibodies (IgA class, ×160) against the BMZ of guinea pig lip skin. Based on the diagnosis of linear IgA dermatosis (LAD) of childhood, administration of dexamethasone (2 mg/day) was started, and the eruptions diminished immediately. Western blot analysis using extract of the HaCaT cell as a substrate, demonstrated the corresponding antigen at 120‐kDa molecular weight. There have been 213 cases of LAD reported in Japan including conference abstracts and these were studied to determine whether infantile cases differed from adult ones, and whether cases associated with IgG as well as IgA (IgA/G type), differed from the cases associated with IgA only (IgA type). IgG contributed less frequently to the infantile type (age of onset, ≤15 years) than to the adult type (age of onset, ≥16 years). Clinical appearance did not show any obvious difference between the IgA/G type and IgA type. However, three‐quarters of cases showing localization of antigen to the dermal side were the IgA/G type.     

Human placental amnion is a novel substrate for detecting autoantibodies in autoimmune bullous diseases by immunoblotting

BACKGROUND: Identification of antigens by immunoblotting techniques, using epidermal and dermal extracts, is regarded as essential for making a definitive diagnosis in autoimmune bullous diseases (AIBDs). These procedures involve epidermal-dermal separation for subsequent protein extraction, which may result in partial loss of some antigenic polypeptides and changes in the conformational epitopes targeted by autoantibodies in AIBDs. It may therefore be necessary to use different substrates for consistent results. Objectives To evaluate the usefulness of human placental amnion extract as a substrate for immunoblotting in the diagnosis of AIBDs. METHODS: We checked the structural components of the desmosomes and basement membrane zone (BMZ) of amnion by electron microscopy. Using immunofluorescence and immunoblotting techniques, we tested the amnion immunoreactivity with antibodies to desmosomal and BMZ proteins, and with sera from 76 patients with AIBDs including pemphigus vulgaris, pemphigus foliaceus, bullous pemphigoid (BP), pemphigoid gestationis, linear IgA bullous dermatosis, epidermolysis bullosa acquisita, paraneoplastic pemphigus and mucous membrane pemphigoid. RESULTS: The desmosomes and BMZ of the amnion tissue were ultrastructurally similar to those in skin. Antigen mapping confirmed that amnion contains all the proteins that were recognized by a panel of monoclonal and polyclonal antibodies. Immunoblotting showed that the antibodies clearly detected bands corresponding to desmogleins 1 and 3, desmocollins 1 and 2, desmoplakins 1 and 2, three subunits (alpha3, beta3 and gamma2) of laminin 5, BP antigens 1 and 2, the 97-kDa LAD antigen and type VII collagen. In addition, most of the patient sera (82%) reacted exclusively with their respective antigens. CONCLUSIONS: Harvesting proteins from amnion does not require epidermal-dermal separation, and a sufficient yield of desmosomal and hemidesmosomal proteins can be obtained. Therefore, amnion may be a more reliable source of substrate than skin samples for immunoblot analysis of AIBDs.     

Localized pemphigoid: a case report showing in situ deposition as well as presence in serum of IgG and IgA anti-basement membrane zone antibodies

In this paper, we describe a 69-year-old Japanese woman with localized pemphigoid. Direct immunofluorescence study showed linear IgG, IgA and C3 deposits at the basement membrane zone (BMZ). In the serum, circulating anti-BMZ antibodies of both IgG and IgA classes were found. This is the first report of a patient with localized pemphigoid in whom circulating anti-BMZ antibodies of not only the IgG class, but also of the IgA class were present.