Pemphigoid without mucosal involvement showing autoantibodies against laminin-332 γ2 subunit

Case Report: The many faces of bullous pemphigoid

The pemphigoid group comprises a number of bullous skin diseases with autoantibodies against different constituents of the basement membrane zone that result in subepidermal detachment and clinically characteristic tense blisters, erosions, urticarial erythema, and itching. Apart from the most frequent type of bullous pemphigoid with antibodies against BP180, which is found predominantly in elderly patients, the disease may present at other ages and different pathogenic conditions. Here, four cases are presented of young age (3 months and 25, 34, and 46 years) and in association with vaccination, pregnancy, or metastatic cancer. Though anti-BP180 was found in all cases, a different pathogenic background may be found in any of them, resulting in characteristic clinical manifestation, yet demanding specifically adapted therapeutic approaches.

Usefulness of immunofluorescence overlay antigen mapping in the identification of autoantigen in anti-p200 pemphigoid

Anti-p200 pemphigoid is a rare subepidermal blistering disease showing immunoglobulin G (IgG) autoantibodies reactive with a 200-kDa protein. In most patients, serum IgG antibodies react with laminin γ1. The diagnosis of anti-p200 pemphigoid is occasionally difficult, mainly due to the lack of standardized tests. We performed fluorescence overlay antigen mapping by laser scanning confocal microscopy (FOAM-LSCM) to identify autoantigens in an anti-p200 pemphigoid patient and assessed its usefulness for the diagnosis. A 71-year-old man presented with blisters and erosions on the bilateral forearms. No mucosal lesions were observed. Laboratory examinations revealed mild leukocytosis and antinuclear antibody negativity. A histopathological examination showed subepidermal blisters with neutrophil infiltration. Direct immunofluorescence showed linear IgG staining along the basement membrane zone. Indirect immunofluorescence using 1 M NaCl-split skin sections revealed IgG reactivity on the dermal side. Immunoblotting detected circulating IgG autoantibodies that reacted with a 200-kDa protein. Accordingly, anti-p200 pemphigoid was diagnosed. FOAM-LSCM revealed that the patient's IgG signals were co-localized with laminin γ1 but were observed above type VII collagens. A direct immunofluorescent analysis for IgG deposition patterns showed an n-serrated pattern. Thus, FOAM-LSCM may be useful for diagnosing anti-p200 pemphigoid.

A long-term study of a patient with anti-p200 pemphigoid: correlation of autoantibody levels with disease activity and an example of epitope spreading

Anti-p200 pemphigoid is a rare subepidermal blistering disease associated with autoantibodies against a 200-kDa protein, reportedly corresponding to laminin γ1. However, direct evidence of the pathogenic potential of these antibodies has not been proven. For 5 years we have followed up a patient with anti-p200 pemphigoid. During this period she experienced a total of three generalized relapses. Quantifying our patient's autoantibody concentrations against laminin γ1 by enzyme-linked immunosorbent assay throughout the course of her disease we demonstrated a clear correlation with disease activity, thus providing the first evidence of the possible pathogenic role of antibodies against laminin γ1 in anti-p200 pemphigoid. Further analysis by Western blotting revealed the occurrence of additional autoantibodies against the α3 chain of laminin 332, 1·5 years after diagnosis, suggestive of intermolecular epitope spreading. Yet, the clinical appearance was unchanged and mucous membranes remained unaffected at any stage of the disease.

Immunofluorescence serration pattern analysis as a diagnostic criterion in antilaminin-332 mucous membrane pemphigoid: immunopathological findings and clinical experience in 10 Dutch patients

BACKGROUND

Antilaminin-332 mucous membrane pemphigoid (anti-LN-332 MMP) is a chronic subepidermal blistering disease characterized by IgG anti-epidermal basement membrane zone (BMZ) autoantibodies against laminin-332 (LN-332).

PATIENTS

with anti-LN-332 MMP have an increased relative risk of malignancy. Laboratory techniques that are difficult to obtain are needed for diagnosis of anti-LN-332 MMP. Objectives  To incorporate direct immunofluorescence (DIF) serration pattern analysis of IgG depositions in the diagnostic criteria of anti-LN-332 MMP.

METHODS

Patients who met our revised inclusion criteria for anti-LN-332 MMP were selected from our biobank over the period 1997-2009. Inclusion criteria were clinical symptoms, DIF serration pattern analysis, indirect immunofluorescence (IIF) on salt-split skin, and antigen-specificity analysis of the serum including immunoblotting and/or immunoprecipitation and/or enzyme-linked immunosorbent assay (ELISA) against native LN-332.

RESULTS

Ten patients met the inclusion criteria. A malignancy was found in two patients (20%). In all patients in whom it was performed (n = 9), DIF showed linear IgG deposition along the BMZ in an n-serrated pattern. Nine sera reacted by salt-split skin analysis and bound to the dermal side of the split skin. ELISA against native LN-332 was positive in 78% of the tested sera.

CONCLUSIONS

Anti-LN-332 MMP can clinically resemble other forms of pemphigoid. Although state-of-the-art laboratory diagnostics are necessary for definite diagnosis, the combination of simple DIF serration pattern and IIF salt-split skin analysis will exclude other forms of MMP and epidermolysis bullosa acquisita from the differential diagnosis. Because of the increased risk for malignancy patients should be thoroughly oncologically screened.