Two-step TCR zeta/CD3-CD4 and CD28 signaling in T cells: SH2/SH3 domains, protein-tyrosine and lipid kinases.

A central question in T-cell immunity concerns the nature of intracellular 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 p56lck, 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 kinases in the generation of signals from the TCR zeta/CD3 complex and the CD28 antigen.