Simultaneous presence of mucous membrane pemphigoid and pemphigus vulgaris: Molecular characterization of both autoantibodies

There are several reports in the literature describing the coexistence of f eatures of pemphigus vulgaris and pemphigoid in the same patient. We descri be 15 patients with clinical, histological, and immunopathological features of mucous membrane (cicatricial) pemphigoid at the time of initial diagnos is. All 15 patients failed to respond clinically to conventional systemic a gents over a mean period of 7.2 years. Hence, IVIg therapy was used. Prior to initiating Mg therapy, features of mucous membrane pemphigoid and pemphi gus vulgaris were demonstrated by various serological tests. Different assa ys were performed to identify molecular characteristics of these two autoan tibodies. Twenty-five healthy normal individuals, 22 patients with mucous m embrane pemphigoid, 17 patients with pemphigus vulgaris, and 12 patients wi th pemphigus foliaceus served as controls for comparison of serological stu dies. On indirect immunofluorescence, using monkey esophagous as substrate, sera of all 15 patients had demonstrable levels of anti-intercellular ceme nt substance (ICS) or anti-keratinocyte cell surface antibody. Sera of 14 p atients on salt split skin bound to the epidermal side of the split, which was consistent with mucous membrane pemphigoid. Sera of all 15 patients dem onstrated binding to a 205-kDa protein (human B4 integrin) and a 130-kDa pr otein (desmoglein 3) on immunoblot. In a sample of sera from each of the 6 patients with mucous membrane pemphigoid and pemphigus vulgaris, the anti-I CS antibody was of the IgG4 subclass. The IgG4 subclass is a characteristic feature associated with pathogenic autoantibodies in pemphigus vulgaris. H ence, in such patients, a dual diagnosis should be considered and confirmed by various serological assays. It is possible that the presence of two pat hogenic autoantibodies in these patients could have contributed to the lack of response to conventional immunosuppressive therapy. (C) 2001 Academic P ress.