Analysis of antigens targeted by circulating IgG and IgA antibodies in patients with mucous membrane pemphigoid predominantly affecting the oral cavity

Background: Mucous membrane pemphigoid (MMP) includes a range of variants frequently having oral, particularly gingival, lesions. It has been suggested that MMP exclusively involving the oral cavity could be a distinct subset, but the immunological status of patients with predominantly oral lesions has received little attention. Methods: Indirect immunofluorescence (IIF) on normal human skin and normal human salt-split skin (SSS) as a substrate and immunoblotting on extracts of human keratinocyte cultures and normal human skin were carried out in 28 consecutive patients with MMP predominantly affecting the gingiva. Results: There was no significant difference between frequency of positive SSS-IIF among patients with exclusive oral lesions (42%) and with MMP not restricted to the oral cavity (78%) (P = 0.114). By immunoblotting, IgG of 13 sera (46%) reacted with the 180 kD bullous pemphigoid antigen (BPAg2), six (21%) reacted with the 230 kD bullous pemphigoid antigen (BPAg1), and two (7%) reacted with an antigen of 200 kD. IgA of three sera (11%) reacted with BPAg2 and three (11%) reacted with BPAg1. There was no significant difference between frequency of positive immunoblotting among patients with exclusive oral lesions (68%) and with MMP not restricted to the oral cavity (67%) (P = 1.00). Conclusions: Most of the MMP sera contain IgG and IgA antibodies to the two major bullous pemphigoid antigens, independent of clinical presentation. Thus, in the majority of cases, patients with exclusively gingival pemphigoid lesions do not appear to have a distinct variety of mucous membrane pemphigoid.