Linear IgA disease in adults

Abstract

A multi-centre study is described in which thirty-five adult patients with papillary IgA dermatitis herpetiformis (DH) were compared with forty-two patients with linear IgA deposits, of whom thirty-four had homogeneous-linear (HL) and eight had granular-linear (GL) IgA deposits. The three groups were similar with regard to age of onset, presence of circulating immune complexes and auto-antibodies, incidence of spontaneous remission, histology of lesional skin and response to dapsone. There was a female predominance in the HL group in contrast to the male predominance in the other two. It was not possible to diagnose the HL group clinically. Some patients had a rash typical of DH whilst others resembled pemphigoid. In the majority, however, no specific diagnosis could be made with confidence. The GL group clinically resembled the DH group. The incidence of positive potassium iodide patch tests was greater in the DH group than in the other two. An associated enteropathy was found in 24% of patients in the HL group, 30% of patients in the GL group and 85% of patients in the DH group. Fifty-six percent of HL patients had HLA-B8 compared with 50% in the GL group and 88% in the DH group. Patients with linear IgA deposits may not be a uniform group, but until they can be divided into specific subgroups (e.g. by ultrastructural localization of the deposit or by response to a gluten-free diet) we propose that the term adult linear IgA diseases should be used to distinguish these patients from those with papillary IgA deposits.

Identification of the cutaneous basement membrane zone antigen and isolation of antibody in linear immunoglobulin A bullous dermatosis.

“…Lanes 2-4 are patients with LABD (patients 1-3, Table I). Results on patient 4 were similar (not shown). Lanes 5-7 were exposed to the normal human sera.…”

“…LABD is an uncommon blistering disease of the skin in which a vesicle forms in the basement membrane zone in association with the linear deposition of IgA in perilesional skin (1,4,7 IgA-class autoantibodies that bound to the basement membrane of monkey esophagus, a common substrate for detection of basement membrane autoantibodies. When indirect immunofluorescence was performed on our sera using 1 M salinesplit skin as a substrate, 9 of 10 LABD sera demonstrated circulating IgA-class anti-basement membrane antibody, pointing out the superiority of saline-split skin as a substrate for detection oflow titer basement membrane zone antibodies.…”

“…Mouse monoclonal antibody to laminin (Calbiochem-Behring Corp., San Diego, CA) was used at a dilution of 1:50 and the second antibody was fluorescein-conjugated goat antimouse IgG (IgG fraction, 13.5 mg/ml protein, 4 10 min, and the supernatant discarded. The pellet was washed for 10 min three times in PBS, and then incubated in 5 cm3 of20 mM sodium citrate (pH 3.2) for 6 h at 37°C.…”

“…However, LABD has been separated from classical dermatitis herpetiformis that demonstrates granular deposition of IgA in dermal papillary tips. Patients with dermatitis herpetiformis also have a high frequency of the HLA B8 DR3 haplotype, and gluten-sensitive enteropathy, which is not present in LABD patients (3,4). Some patients with LABD demonstrate a circulating IgA-class anti-basement membrane antibody on indirect immunofluorescence, whereas sera from patients with dermatitis herpetiformis have not demonstrated a circulating antibody that binds to skin (2).…”

LINEAR IgA DISEASE: A RARE ENTITY

“…The HLA B8 DR3, known as autoimmune extended haplotypes, is associated with LAD. (4,5,6) Histological features are not specific for this condition. Sub epidermal vesicles may contain Eosinophils (suggestive of bullous pemphigoid) or neutrophils (suggestive of dermatitis herpetiformis).…”