3DO cells were cultured for different times in 96-well plates coated with anti-CD3 MoAb (1 μg/mL). Results are expressed as the percentage of apoptotic nuclei, the median of Fas expression histogram, the percentage of FasL⁺ cells, the amount of IL-2 in pg/mL, the percentage of IL-2R⁺ cells, and are the means of three separate experiments. The standard errors (<10%) are omitted for clarity.

Blocking peptide, at a concentration 10-fold higher then anti-FasL antibody was used, in two experiments, to control the specificity of the staining. Addition of the peptide inhibited the FasL staining down to 2.1% (first experiment) and 2.6% (second experiment), respectively, compared with anti-CD3 (18 h)-treated cells giving 57.2% (first experiment) and 58% (second experiment).