Direct Immunofluorescence in Behçet's Disease: A Controlled Study with 108 Cases

PURPOSE: Behçet's disease (BD) is a disease of unknown etiology, which has multisystemic involvement. This multisystemic involvement might be the clue for an autoimmune pathogenesis. In order to evaluate an autoimmune pathogenesis, we examined immunoreactans depositions in the skin of BD patients. MATERIALS AND METHODS: The skin samples of 108 BD patients (28 perilesional skin, 44 positive pathergy test site, 22 negative pathergy test site, 14 normal skin) were examined for the depositions of immunoglobulin (Ig)M, IgG, IgA, complement 3 (C(3)), and fibrinogen (F) using direct immunofluorescence (DIF). The data were statistically compared to the DIF of 36 systemic lupus erythematosus (SLE) patients and 20 healthy controls using χ(2) Fisher exact test. RESULTS: Highly significant immunoreactans depositions were obtained in BD (deposition rates: IgM 70.3%, IgG 0%, IgA 20.3%, C(3) 62.9%, F 83.3%). The comparison with SLE revealed no differences in IgM, IgA, and C(3). However, IgG deposition was higher in SLE while F deposition was higher in BD. In both BD and SLE, the Ig depositions were highly significant when the data were compared with the healthy controls. CONCLUSION: The significant deposition of immunoreactans in BD, especially in the negative pathergy and the normal skin sites, were observed. This study is the first controlled study revealing positive Ig depositions in BD, and it is expected to help us to reconsider the autoimmune pathogenesis in BD.