Recent Advances in T Cell Signaling in Aging

The immune system of mammalian organisms undergoes alterations that may account for an increased susceptibility to certain infections, autoimmune diseases, or malignancies. Well characterized are age related defect in T cell functions and cell mediated immunity. Although it is well established that the functional properties of T cells decrease with age, its biochemical and molecular nature is poorly understood. The available data suggest that changes in the signal transduction machinery are responsible for the impairment of T cell function during aging. T cell activation is initiated when an antigenic peptide is recognized by the antigen receptor of T cells. This recognition event promotes sequential activation of a network of signaling molecules such as phospholipases, kinases, phosphatases, and adaptor proteins that couple the stimulatory signal received from T cell receptor (TCR) to intracellular signaling pathways. The coordinate activation of these signaling molecules is sufficient to stimulate the activation of transcription factors and the expression of the immediate early genes that are crucial in regulation of T cell function.