Detection of pemphigus autoantibodies by IIF and ELISA tests in patients with pemphigus vulgaris and foliaceus and in healthy relatives

BACKGROUND: Pemphigus is a life-threatening, autoimmune blistering disease, mediated by IgG autoantibodies. The aim of our study was to assess the usefulness of a new enzyme-linked immunosorbent assay (ELISA) in detecting circulating pemphigus autoantibodies, and to compare its sensitivity and specificity with the indirect immunofluorescence (IIF) test. We also established the frequency of occurrence of pemphigus autoantibodies in relatives of our patients.MATERIAL/METHODS: IIF and ELISA tests were performed in 24 patients with pemphigus vulgaris, 13 with pemphigus foliaceus, 56 healthy relatives, and 50 controls, selected according to sex and age.RESULTS: The obtained results revealed high specificity and sensitivity of ELISA, comparable to the IIF test, especially in patients who were in the active stage of the disease. We also showed that the profile of anti-Dsg 1 and/or anti-Dsg 3 autoantibodies is associated with the clinical variant of pemphigus. The frequency of occurrence of pemphigus autoantibodies in the relatives (24/55) performed by IIF was significantly higher (p<0.001) than in the controls (0/50). The same antibodies detected by ELISA (11/56) were less frequent.CONCLUSIONS: In clinically doubtful cases, in which autoantibodies titres by IIF are equal on both substrates (monkey and guinea pig esophagus), the assessment of the exact antibody profile (anti-Dsg 1 and/or anti-Dsg 3) is important to establish the subtype of pemphigus. The frequency of pemphigus antibody occurrence in healthy relatives seems not to be incidental, but further studies should be performed to explain this phenomenon.