Dr. Xu's research interests focus on the roles of T cells in autoimmune diseases. His main research areas include: 1) the mechanisms and potential therapeutics, of autoimmune diseases e.g. experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. He is currently using IDO deficient mice to investigate the role of IDO in Th17-mediated immune responses and explore the therapeutic effects of tryptophan metabolites on EAE. 2) the role of MS4a4B, a novel member of CD20 gene family, in T cell development and T cell-mediated immunity, including the regulatory function of MS4a4B in T cell proliferation and apoptosis.