IgG/IgA pemphigus with IgG and IgA antidesmoglein 1 antibodies detected by enzyme-linked immunosorbent assay

Pemphigus is an autoimmune mucocutaneous bullous disease characterized by autoantibodies against the cell surfaces of epidermal keratinocytes. Six cases with deposition of both IgG and IgA on keratinocyte cell surfaces have been reported in the recent literature. We provisionally termed these cases IgG/IgA pemphigus. We describe a 42-year-old Japanese woman with clinical and histopathological features resembling herpetiform pemphigus who demonstrated in vivo bound and circulating anticell surface autoantibodies of both IgG and IgA classes on immunofluorescence examination. Enzyme-linked immunosorbent assay using baculovirus-expressed recombinant desmoglein (Dsg) 1 and Dsg 3 showed that both IgG and IgA antibodies reacted with Dsg1. The reactivity was completely adsorbed with preincubation of serum with Dsg1 baculoprotein, further confirming the exclusive reactivity of both IgG and IgA antibodies with Dsg1. This is the second case of IgG/IgA pemphigus in which the human target antigens for both IgG and IgA antibodies have been unequivocally identified. This study provides further evidence that IgG/IgA pemphigus is a distinct disease entity.

Pemphigus foliaceus with prominent neutrophilic pustules

We describe four patients with generalized scaly and pustular skin lesions showing extensive neutrophilic infiltration in the subcorneal region of the epidermis. Immunofluorescence, immunoblot and enzyme-linked immunosorbent assay analyses detected IgG antibodies reacting exclusively with desmoglein 1, the pemphigus foliaceus antigen. This study indicates that pemphigus foliaceus may show prominent neutrophilic pustular skin lesions.

Detection of IgA autoantibodies to desmogleins by an enzyme-linked immunosorbent assay: the presence of new minor subtypes of IgA pemphigus

OBJECTIVE

To examine the frequency of antidesmoglein 1 (Dsg1) and antidesmoglein 3 (Dsg3) IgA autoantibodies in IgA pemphigus.

DESIGN

We developed an enzyme-linked immunosorbent assay against recombinant Dsg1 and Dsg3 to detect IgA autoantibodies.

PATIENTS

Twenty-two patients with IgA pemphigus were studied. Among them, 10 patients had subcorneal pustular dermatosis type, 9 patients had intraepidermal neutrophilic IgA dermatosis type, and 3 patients had pemphigus foliaceus-like clinical features.

RESULTS

Of the 22 cases of IgA pemphigus, 3 cases were positive for anti-Dsg1 IgA antibodies and only 1 case was positive for anti-Dsg3 IgA antibodies. In those 4 cases, there were no IgA autoantibodies against other components of the keratinocyte cell surfaces because preincubation with the respective recombinant desmogleins removed the immunoreactivity on immunofluorescence. All 10 patients with subcorneal pustular dermatosis type IgA pemphigus were positive against desmocollin 1 expressed on COS-7 cells. No target antigen was detected in the other 8 cases.

CONCLUSIONS

Desmogleins were recognized by IgA antibodies of a few patients with IgA pemphigus. Considering that subcorneal pustular dermatosis type IgA pemphigus recognizes desmocollin 1, autoimmune targets of IgA pemphigus are more heterogeneous than previously considered.

The clinical transition between pemphigus foliaceus and pemphigus vulgaris correlates well with the changes in autoantibody profile assessed by an enzyme-linked immunosorbent assay

BACKGROUND

There are a number of reports of pemphigus with clinical shifting between pemphigus foliaceus (PF) and pemphigus vulgaris (PV). On the other hand, a novel enzyme-linked immunosorbent assay (ELISA) against recombinant baculoproteins of desmoglein 1 (Dsg1) (PF antigen) and Dsg3 (PV antigen) has been established and found to be extremely sensitive and specific.

OBJECTIVES

To characterize the change in the antibody profiles in a series of pemphigus cases with mixed features of PF and PV by various methods, including the novel ELISA. Patients/methods Sera were obtained from eight cases undergoing a shift between PF and PV and three cases of coexistent PF and PV. The autoantigens were analysed by ELISA, as well as by immunofluorescence using normal human skin sections and immunoblotting using normal human epidermal extracts.

RESULTS

The results of the ELISA, immunofluorescence and immunoblotting studies showed that the transition between PF and PV correlates well with the changes of autoantibodies against either Dsg1 or Dsg3.

CONCLUSIONS

The clinical phenotype at each stage is defined by the anti-Dsg antibody profile in the serum of these pemphigus patients showing mixed features of PF and PV. In addition, ELISA using recombinant baculoproteins was particularly useful in distinguishing PF and PV.

Antidesmoglein autoantibodies in silicosis patients with no bullous diseases

BACKGROUND

Pemphigus is an autoimmune bullous disease characterized by the presence of antidesmoglein autoantibodies. However, the mechanism of its autoantibody production remains unknown. In previous reports, we have described rare cases of pemphigus and pemphigoid associated with silicosis. It is well known that during long-term silicosis, some autoimmune diseases, such as systemic sclerosis, systemic lupus erythematosus or rheumatoid arthritis, can occur.

OBJECTIVE

The aim of this study was to explore the presence of pemphigus or pemphigoid autoantibodies in silicosis patients without clinical bullous diseases or collagen diseases.

METHOD

The presence of pemphigus antibodies was examined in 54 silicosis patients with no associated bullous diseases, using immunofluorescence, the enzyme-linked immunosorbent assay (ELISA) for desmoglein 1 and 3, and immunoblotting methods. In the antibody-positive cases, HLA genotyping of peripheral lymphocytes was performed with PCR-RFLP.

RESULTS

Seven out of the 54 patients were found to be positive for pemphigus antibodies and 1 for bullous pemphigoid by immunofluorescence. In addition, by ELISA, 6 patients were found to be positive against the desmoglein 1 antigen, 2 against the desmoglein 3 antigen and 2 against both desmoglein 1 and desmoglein 3.

CONCLUSION

The results of the present study strongly suggest the occurrence of pemphigus and pemphigoid autoantibodies in patients with silicosis. It remains unclear whether such patients will develop an autoimmune bullous disease in the future. Accordingly, long-term follow-up of antibody-positive patients is required.

Bullous pemphigoid associated with silicosis

Bullous pemphigoid (BP) has never before been reported to associate with silicosis, although there are numerous reports of silicosis accompanied by different autoimmune diseases, such as systemic sclerosis, systemic lupus erythematosus, dermatomyositis or rheumatoid arthritis. We report on a 63-year-old Japanese patient with silicosis who developed tensed bullae, erosions and macular pigmentation on the trunk and extremities. Indirect immunofluorescence revealed anti-basement-membrane-zone antibodies; immunoblotting analysis demonstrated that the patient's serum reacted with the 230-kD BP antigen in the epidermal extracts, as well as a recombinant protein of the NC16a domain of 180-kD BP antigen. Clinical symptoms improved after treatment with systemic steroids. To the best of our knowledge, this is the first reported case of BP associated with silicosis.

Immunopathological diagnosis of cicatricial pemphigoid with desquamative gingivitis. A case report

Cicatricial pemphigoid (CP) is a chronic subepidermal bullous dermatosis which primarily involves the mucous membranes. The oral cavity and the eye are most frequently involved. Since extension of the lesion into the pharynx and esophagus causes sore throat and dysphagia and progressive ocular lesions may cause blindness, early and valid diagnosis is very important. Here we present a case of cicatricial pemphigoid with onset at age 45 in a patient who manifested severe periodontal disease and showed the lesion on the mucous membranes of the mouth (desquamative gingivitis), skin, and eyes. Since definite diagnosis is very important, we describe how we made a differential diagnosis from other diseases which also accompany desquamative gingivitis. We examined the clinical manifestations, blood test results, HLA-genotype, histopathologic findings of the affected tissue, and immunological findings in relation to autoimmunity. Since many of the CP cases are first referred to periodontists or dentists, we believe that the diagnostic strategy described in the present study will be quite informative for making rapid and definite diagnoses of similar cases.

Pemphigoid nodularis with IgA autoantibodies against the intracellular domain of desmoglein 1

Pemphigoid nodularis is a rare variant of bullous pemphigoid. We report a 49-year-old Japanese male with clinical and histopathological features of pemphigoid nodularis including circulating and in vivo-bound IgG antibasement membrane zone antibodies and IgA anti-intercellular antibodies. Although the precise molecular target of the IgG autoantibodies could not be determined, intriguingly, immunoblotting showed that the IgA in the patient's serum reacted with the intracellular domain of desmoglein 1, the target antigen in cases of pemphigus foliaceus. However, the IgA did not react with the extracellular domain of desmoglein 1 in sensitive enzyme-linked immunosorbent assay studies using a baculovirus system. These results suggest therefore that these IgA antibodies may possibly not be pathogenic. The mechanism for the production of different autoantibodies is unknown, but this case provides further illustration of the atypical skin immunoreactants often seen in this unusual subtype of bullous pemphigoid.

Desmoglein 1 and desmoglein 3 are the target autoantigens in herpetiform pemphigus

OBJECTIVE

To determine the cell surface autoimmune target of herpetiform pemphigus (HP).

DESIGN

Serum samples of HP were examined by immunoblot studies with human epidermal extracts, enzyme-linked immunosorbent assay with baculovirus-expressed recombinant desmoglein (rDsg) 1 and rDsg3, and immunoadsorption assay with rDsg.

PATIENTS

Twenty serum samples were obtained from patients with HP who have typical clinical and histological features. All serum samples showed positive staining against keratinocyte cell surfaces by indirect immunofluorescence studies with healthy human skin.

RESULTS

Immunoblot results showed that of 17 HP serum samples, only 5 reacted with a 160-kd band and 1 reacted with a 130-kd band. Results of enzyme-linked immunosorbent assays with rDsg1 and rDsg3 demonstrated that of 20 HP serum samples, 16 were positive against Dsg1 and 4 were positive against Dsg3. No serum samples reacted with both. Furthermore, in 19 of 20 HP serum samples, immunoreactivity against keratinocyte cell surfaces was completely removed by preincubation with rDsg1 and rDsg3 as shown by indirect immunofluorescence, excluding a possibility that these HP sera contain autoantibodies against other cell surface molecules.

CONCLUSIONS

Dsg1 and Dsg3 are the major cell surface target molecules of HP, suggesting that most cases of HP are clinical variants of pemphigus foliaceus and that the rest might be variants of pemphigus vulgaris.

Usefulness of enzyme-linked immunosorbent assay using recombinant desmogleins 1 and 3 for serodiagnosis of pemphigus

Pemphigus is an autoimmune blistering disease with two major subtypes, pemphigus vulgaris (PV) and pemphigus foliaceus (PF). Patients with pemphigus have circulating antidesmoglein (Dsg)1 and/or anti-Dsg3 IgG autoantibodies. We have previously developed enzyme-linked immunosorbent assays (ELISAs) using recombinant Dsg1 and Dsg3 expressed by baculovirus as a diagnostic tool for pemphigus. The purpose of this study was to evaluate the practical application of these ELISAs for clinical use with a large number of serum samples. We used 81 PV sera, 48 PF sera, 114 bullous pemphigoid (BP) sera, 124 collagen disease sera, nine sera of other non-pemphigus bullous diseases and 179 normal control sera. A cut-off value was determined by receiver-operating-characteristic plots. Forty-seven of 48 PF sera (97.9%) were positive in the Dsg1 ELISA and 79 of 81 PV sera (97.5%) were positive in the Dsg3 ELISA, while only two (1. 1%) and four (2.2%) of 179 normal sera were positive in Dsg1 and Dsg3 ELISAs, respectively. However, some disease control sera of BP and collagen diseases exceeded the cut-off value. Introduction of a grey zone helped to decrease the number of these false-positive sera. Furthermore, in three patients studied, the respective Dsg1 and Dsg3 ELISA scores showed parallel fluctuation with the disease activity along the time course. We conclude that Dsg1 and Dsg3 ELISAs provide a simple, sensitive and highly specific assay for the diagnosis of patients with PV and PF and that these ELISAs may be a valuable tool to monitor the disease activity. We also propose diagnostic criteria for pemphigus based on ELISA reactivity: if a serum is positive against Dsg3 it indicates a diagnosis of PV, regardless of reactivity against Dsg1; if a serum is negative for Dsg3 and positive for Dsg1, it indicates a diagnosis of PF.

Application of confocal laser scanning microscopy to differential diagnosis of bullous pemphigoid and epidermolysis bullosa acquisita

We applied confocal laser scanning microscopy to fluorescence overlay antigen mapping (FOAM) for differential diagnosis of bullous pemphigoid (BP) and epidermolysis bullosa acquisita (EBA). FOAM of tissue-bound IgG and marker basement membrane components (BMCs) including integrin beta 4, laminin-1, laminin-5 and type IV collagen, showed that tissue-bound IgG in perilesional skin samples from five patients with BP was localized on the epidermal side of type IV collagen, and colocalized with some of the other three BMCs, whereas IgG in a sample from a patient with EBA was on the dermal side of all the BMCs. FOAM of binding sites of autoantibodies in patients' sera and markers including integrin beta 4, laminin-1, type IV collagen and type VII collagen, showed that the binding sites of autoantibodies from 16 patients with BP were localized on the epidermal side of type IV and type VII collagens, and localized above or codistributed with integrin beta 4 and laminin-1, whereas those from five patients with EBA were codistributed with type IV and type VII collagens, and localized on the dermal side of integrin beta 4 and laminin-1. These spatial relationships are compatible with their previously described ultrastructural locations. Thus, this method appears to be useful in the differential diagnosis of BP and EBA.

Systemic sclerosis associated with diabetes insipidus

A rare case of systemic sclerosis that preceded the development of diabetes insipidus is reported. This 25-year-old man presented with Raynaud's phenomenon and ulceration of the tip of the right thumb. The diagnosis of systemic sclerosis was based on findings of proximal scleroderma, sclerodactyly, serological abnormalities, and skin abnormalities verified histologically. Partial central diabetes insipidus was later diagnosed after the sudden appearance of polyuria and polydipsia. Coexistence of systemic sclerosis with diabetes insipidus suggests that diabetes insipidus in this patient might have occurred via an autoimmune mechanism.