Figure 1

Costimulatory effect of CD81 stimulation on CD69 expression (A, C, E, and G) and IL-2 production (B, D, F, and H), measured by cytokine flow cytometry. Whole blood from a CMV seropositive donor was stimulated for 6 h with varying concentrations of SEB (A-D) or CMV (E-H) in the presence of the activator alone (open circles), an irrelevant isotype control antibody (open squares), 5 μg/ml anti-CD28 mAb (closed circles), or 5 μg/ml 5A6 anti-CD81 mAb (closed squares). CD69 and IL-2 were then quantitated by intracellular staining on CD3⁺CD4⁺ cells (A, B, E, F) or CD3⁺CD4^- cells (C, D, G, H). Results are representative of three experiments.