Specific resistance of T cells to CD95-induced apoptosis during S phase of the cell cycle.
We have examined the susceptibility of mouse thymocytes and Con A-activated mature T cells to CD95 (Fas; APO-1)-induced apoptosis at different phases of the cell cycle. Signaling through CD95, induced by murine CD95 ligand expressed on fibroblasts, resulted in the preferential apoptosis of T cells in G0-G1 phase of the cell cycle. T cells in S phase were selectively protected. CD95-induced apoptosis was inhibited by exogenous IL-2, which increases the percentage of cells in S phase. The inverse relationship between DNA synthesis and apoptosis in CD95-ligated T cells was not observed during the spontaneous death of T cells in culture or during propriocidal apoptosis due to TCR cross-linking, to which cells in S phase were susceptible. These results show that in T cells there is no distinctively apoptosis-vulnerable phase of the cell cycle; instead, apoptosis can occur at different phases of the cycle depending on the apoptotic stimulus.
Dao
T
T
Immunobiology Section, Yale University School of Medicine, New Haven, CT 06510, USA.
Huleatt
J W
JW
Hingorani
R
R
Crispe
I N
IN
D000818:Animals; D017209:Apoptosis / Q000276:immunology*; D002453:Cell Cycle / Q000276:immunology*; D005434:Flow Cytometry; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D016196:S Phase; D015398:Signal Transduction / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology / Q000473:pathology*; D019014:fas Receptor / Q000276:immunology*
D019014:fas Receptor