CTLA-4 and T cell activation

The past year has seen significant advances in our understanding of the rol e of cytotoxic T lymphocyte antigen 4 (CTLA-4) in regulating T cell activat ion and tolerance. Recent studies indicate that CTLA-4 not only counterbala nces CD28 signals but also can inhibit T cell responses independently of CD 28. Recent work,has. also revealed a role for CTLA-4 in regulating Th1/Th2 differentiation. Manipulation of CTLA-4 in animal models of autoimmunity ha s shown that CTLA-4 regulates both the initiation and the progression of au toimmune diseases.