IgE and its related phenomena in bullous pemphigoid

This study was designed to analyse IgE and its related phenomena in bullous pemphigoid (BP). We analysed 17 BP sera by indirect immunofluorescence (IIF) and immunoblotting (IB) using a monoclonal antibody to IgE. In addition, inflammatory cells in lesional skin from 11 patients with BP were analysed by the alkaline phosphatase-anti-alkaline phosphatase (APAAP) technique using monoclonal antibodies to IgE and Fc epsilon RII/CD23. IgE class anti-basement membrane zone (BMZ) autoantibody was detected in nine of 17 sera (52.9%) by IIF. IgG class anti-BMZ antibody could block the BMZ-binding reactivity of IgE class antibody. Titres of IgE class autoantibody in the sera ranged from 1:40 to 1:320, and statistically correlated with serum IgE levels. Two of 11 sera contained an IgE class autoantibody which recognized a 230-kDa BP antigen by IB. By radio-allergosorbent test (RAST), IgE-specific antibodies to an extended series of common inhalant and food allergens were detectable in six sera with high concentrations of total IgE (over 3,300 IU/ml). IgE-bearing and Fc epsilon RII-expressing cells were demonstrated in the upper dermis and along the BMZ in seven of 11 biopsy specimens by the APAAP technique. The distribution and number of IgE-bearing cells in the lesions were similar to those of the Fc epsilon RII-expressing cells. These results suggest that both IgE-mediated immune responses and autoimmunity characterize BP as distinctive features.