Effect of the addition of IL-4 or anti–IL-4 mAb on the suppressive activity exerted by a Treg clone on the proliferation of Th1 and Th2 cells. (A) T-cell blasts from 8 Th1 and 9 Th2 clones were stimulated for 5 days with 105 allogeneic irradiated peripheral blood mononuclear cells (PBMNCs) with or without 3 different concentrations of T-cell blasts (target–regulatory cell ratio 1:1, 2:1, and 4:1) from the autologous Treg clone CD4+CD25+ no. 8, in the absence (medium; ▪) or the presence of rIL-4 (▦), anti-IL-4 mAb (□) or isotype control mAb (▨). Results are expressed as mean values (+ SD) of percentage of inhibition of proliferation obtained in triplicate cultures from the 8 Th1 and the 9 Th2 clones. *P < .01. (B) T-cell blasts from both Treg and Th2 clones were cultured for 5 days alone or with 105 allogeneic-irradiated T-cell–depleted PBMNCs in the absence (medium; ▪) or the presence of rIL-4 (▦; 2 ng/mL). One representative experiment is shown.
