Figure 2. Increasing calcium signaling in Tconvs abrogates Treg-mediated suppression.

(A) Purified CD4⁺CD25⁻ Tconvs were cultured alone and were stimulated by PMA and/or ionomycin as indicated. (B-C) CD4⁺CD25⁻ Tconvs were cultured without (gray bars) or with CD4⁺CD25⁺ Tregs at a 1:1 ratio (black bars). Syngeneic APCs and soluble anti-CD3 mAb were used as stimulators. In B, some cultures were supplemented with PMA and/or ionomycin. In C, APCs, Tregs, or Tconvs were pretreated with 750 ng/ml ionomycin for 2 hours, and were washed before culture. As indicated, pretreated APCs, Tregs, or Tconvs were used in cultures, respectively. Cell proliferation was assessed on day 3 by ³H-thymidine incorporation. Figures are representative of 3 experiments.