Apoptosis during lymphoid development.

Recent investigations have provided important insights into how signaling through the antigen receptors determines whether a cell survives or dies. In T cells, Grb2 and MAP kinases play essential roles in differentiating between apoptotic and survival signals. The PTEN phosphatase and Bim, a pro-apoptotic Bcl-2 family member, regulate apoptosis in both T and B cells. In B cells, antigen receptor-mediated death can be rescued by co-stimulation, in which the roles of protein kinase C and BAFF, a TNF family member, have been recently elucidated. In a recently identified mechanism of regulating inflammation, receptors such as c-mer and glycoproteins such as MFG-E8 were found to participate in the clearance of apoptotic cells.