The pathogenic activity of anti-desmoglein autoantibodies parallels disease severity in rituximab-treated patients with pemphigus vulgaris

Background: Pemphigus vulgaris (PV) is an autoimmune blistering disease mediated by IgG autoantibodies targeting desmogleins (Dsgs). The anti-CD20 monoclonal antibody rituximab is increasingly used in corticosteroid-resistant PV patients. In a subset of rituximab-treated patients in remission, high ELISA index values have been reported; however, their significance remains so far unclear. Objective: To address the discrepancy between anti-Dsg3 serum antibody titers and disease severity. Materials & methods: 6 rituximab-treated PV patients were prospectively followed-up for two years and anti-Dsg3 autoantibodies levels and pathogenic activity were measured. Results: All patients achieved complete remission without any serious side effects. Both anti-Dsg3 autoantibodies (p = 0.031) and their pathogenic activity (p = 0.003) were significantly related to disease severity. However, in selected patients, the dissociation index was a more sensitive indicator for PV clinical activity than the ELISA index. Conclusion: Our findings have demonstrated the existence of non-pathogenic autoantibodies in PV patients in remission, establishing the basis for the design of a system able to precisely monitor the course of disease.