Pemphigoid diseases (PDs) are chronic antibody-induced autoimmune diseases (AADs). Autoantigen-specific T helper cells are thought to be centrally involved in the pathogenesis of PDs but remain poorly understood. We have developed antigen-reactive T cell enrichment (ARTE) as a powerful technology for unbiased identification and characterization of autoantigen-specific CD4 regulatory (Tregs) and conventional T cells (Tcon.). A01 will employ ARTE for in-depth characterization of autoreactive T cells from healthy donors and PD patients. Pathogenic and therapeutic T cell functions will be tested in a relevant mouse model.