The laboratory is interested in how the immune system decides whether to destroy or tolerate tissues bearing persistent antigens. We first focus on the T cell antigen receptor, and how its structure, multi-subunit composition, and biochemical functions operate throughout the course of immune responses. We then study how the many other proteins and pathways involved in T cell signaling cooperate to compose a network with emergent properties to determine immune fate. Using cellular, molecular, biochemical, and proteomic techniques, we examine these processes in T cell responses to tumors and transplanted tissues.