Fig. 1.

CD4⁺CD25⁺ Tg4 cells raise the threshold for CD4⁺CD25^- Tg4 proliferation in vitro. (A-E) CD4⁺CD25^- and CD4⁺CD25⁺ Tg4 cells were cultured either alone or in combination (at 1:1) in the presence of irradiated B10.PL Ag-presenting cells and the indicated concentration of WT Ac1-9 or APL. Proliferation was measured by ³[H] thymidine incorporation during the last 18 h of a 90-h culture period, and the results are shown as mean ± SD of triplicate wells. (F) Results in A-E are shown as the percentage of suppression in the presence of Treg.