Defective T cell activation and autoimmune disorder in Stra13-deficient mice

Stra13, a basic helix-loop-helix transcription factor, is up-regulated upon activation of CD4(+) T cells. Here we show that Stra13-deficient mice exhi bit defects in several phases of CD4(+) T cell activation. In vivo, Stra13 deficiency results in ineffective elimination of activated T and B cells, w hich accumulate progressively, leading to lymphoid organ hyperplasia. Conse quently, aging Stra13(-/-) mice develop autoimmune disease characterized by accumulation of spontaneously activated T and B cells, circulating autoant ibodies, infiltration of T and B lymphocytes in several organs and immune c omplex deposition in glomeruli. Our studies identify Stra13 as a key regula tor of lymphocyte activation that is vital for maintenance of self-toleranc e and for constraint of autoimmunity.