FIGURE 2.

ABM Tg CD4⁺CD25⁺ T cells exhibit powerful, TCR-restricted, suppressive properties in vitro. A, ABM Tg CD4⁺CD25⁺ T cells (5 × 10⁴) do not proliferate in response to 3 × 10⁵ irradiated bm12 splenocytes and suppress the proliferation of 5 × 10⁴ CD4⁺CD25⁻ T cells. B, The proliferation of 5 × 10⁴ ABM Tg CD4⁺CD25⁻ T cells in response to 3 × 10⁵ irradiated bm12 splenocytes is powerfully suppressed by increasing numbers of ABM Tg, but not polyclonal C57BL/6, T_Regs. C, Both 5 × 10⁴ ABM Tg CD4⁺CD25⁻ and CD4⁺CD25⁺ T cells proliferate in response to 10⁴ bm12, but not CB6F₁, bone marrow-derived mature dendritic cells. Cell proliferation was estimated in all cases by [³H]TdR incorporation. Data are expressed as the mean cpm of triplicate cultures ± SE. Data portrayed in all panels are representative of at least three independent experiments. D, ABM Tg T_Regs (5 × 10⁴) suppress the proliferation of 5 × 10⁴ TEa CD4⁺CD25⁻ T cells only when bm12 irradiated splenocytes are added to the stimulator CB6F₁ cell population.