Determination of CD95L expression on normal PBMC (before and after PHA/IL-2 activation) and in 2 cases of freshly isolated LGL leukemia (cases no. 4 and 11). The cells were fixed and permeabilized and then stained with anti-CD95L MoAb (C-20) followed by secondary antirabbit-FITC MoAb. The shaded area represents the level of fluorescence obtained with an isotype control MoAb, the unshaded area represents the level with CD95L MoAb.