Two-step TCR /CD3-CD4 and CD28 signaling in T cells: SH2/SH3 domains,

A central question in T-cell immunity concerns the nature of intracetlular signaling from the antigen receptor, the CD4/CD8 co-receptors and the CD28 antigen. Since the original discovery that T-cell receptors such as CD4 can interact with intracellular protein-tyrosine kinases such as p56 t'k, remarkable progress has been made in deciphering the signaling pathways that control T-cell growth and immune function. Here, Christopher Rudd and colleagues examine the role of protein-tyrosine kinases, SH2/SH3 domains and lipid kinase~ in the generation of signals from the TCR¢/CD3 complex and the CD. o. antigen.