Bcl-2 Prevents Apoptosis Induced by Perforin and Granzyme B, but Not That Mediated by Whole Cytotoxic Lymphocytes

Abstract

Two pathways have been implicated in the induction of apoptosis by cytotoxic T cells: the granule exocytosis pathway and a pathway using CD95 (Fas/APO-1). To test whether apoptosis induced by either of these pathways could be blocked by Bcl-2, we exposed bcl-2-transfected cells to CTL derived from normal, perforin-deficient, or CD95 ligand mutant (gld) mice. Although the levels of Bcl-2 expression achieved were able to protect FDC-P1 and Yac-1 transfectants from a variety of apoptotic stimuli, the cells were not protected from cytolysis mediated by CTL from any of these sources, by NK cells, or granules isolated from CTL. However, Bcl-2 expression significantly inhibited apoptosis induced by..