FasL expression evaluated by the cytotoxicity assay (see Materials and Methods) with 3DO cells untreated or treated with anti-CD3 (1 μg/mL) and/or IL-6 (20 ng/mL) for 18 hours. The results are the average of three experiments (each in triplicate culture). The standard errors (<10%) are omitted for clarity. E:T ratio, 25:1. *P < .01 comparing anti-CD3– + IL-6–treated versus anti-CD3–treated group.