Figure 6

CD81 costimulation induces preferential proliferation of IL-4-producing cells. CD45RO⁺ PBMC were labeled with CFSE as described in Materials and Methods. They were then stimulated with plate-bound anti-CD3 mAb in the presence or absence of 5 μg/ml 5A6 anti-CD81 mAb for 1, 4, or 7 days. At these time points, cells were restimulated for 4 h with PMA+ionomycin, and cytokine-producing T cells were enumerated by intracellular staining. (A) The percentage of IL-4-producing cells increased faster over time in anti-CD81 mAb-treated cultures. (B) CFSE content of all cells at day 0 (left panel) was equal in the presence of anti-CD81 mAb (solid histogram) or in its absence (dotted histogram). The CFSE content of IL-4-producing cells (right panel) was lower in the presence of anti-CD81 mAb (solid histogram) than in its absence (dotted histogram), after 4 days of stimulation. (C) The mean CFSE content of IL-4-producing cells was lower in the presence of anti-CD81 mAb than in its absence (left panel); there was no such difference for IL-4-negative cells (right panel). (D) The mean CFSE content of IFNγ-producing or IFNγ-negative cells did not differ in the presence or absence of anti-CD81 mAb. Thus, CD81 costimulation preferentially induces proliferation of IL-4-producing cells. Results are representative of two similar experiments.