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