Resistance of lymphoma cells to CD95, but not perforin, lytic mechanisms of cytolytic T cells. Allogeneic antilymphoma T cells generated by MLR were preincubated for 2 hours with 5 ng/mL PMA and 1.5 μg/mL ionomycin. The subsequent 4-hour cytotoxicity assay was performed with Jurkat (A) or lymphoma B cells (B) in the presence of medium (•) or EGTA-Mg²⁺ (□). The cytotoxicity intensity was evaluated by the percentage of ⁵¹Cr-release. Experiments 1 and 2 were performed with lymphoma cells isolated from LCL-3 and MCL-1 patients, respectively.