Tc1 and Tc2 clones show differential susceptibility to apoptosis.

AICD was induced in a number of Tc1 and Tc2 clones by 5 hours of stimulation with immobilized anti-CD3. After treatment, the cells were stained with annexin V–FITC and propidium iodide and analyzed as described in Materials and Methods. The percentage of apoptotic cells is shown in the lower right quadrants. Induction of apoptosis was partially blocked by anti–Fas L antibody (NOK2). Apoptosis was also induced by direct Fas ligation (CH11, anti-Fas MoAb). Two representative clones are shown.