Sensitivity of lymphoma cells to apoptosis mediated by Fas receptor and by TRAIL. Fas-mediated (A) and TRAIL-mediated (B) apoptosis were investigated in 18 lymphoma cell lines. Specific apoptosis was determined in an 18-hour propidium iodide assay. One out of 2 experiments is shown. Concordant results were obtained in both experiments. Jurkat cell line was used as positive control.