CD4XL alone is sufficient to up-regulate CD95 expression in both CD4 T cells and CD8 T cells.

PBTs were pretreated with CD4XL at 37°C for 40 minutes or for 24 hours. Thereafter, anti-CD3 mAb was added with or without anti-CD28 mAb and cells were cultured for 18 hours. CD95 expression was analyzed by flow cytometry. Histograms obtained from the indicated conditions are shaded, and histograms from time-matched medium control (unshaded) are also indicated in panels 1 through 12. Data represent 1 of 3 experiments.