CD4⁺CD25⁺ cells are hyporesponsive to polyclonal T-cell stimuli.

(A-D) The proliferative responses of CD4⁺CD25⁺(■) and CD4⁺CD25⁻ (▪) cells to various stimuli are shown. In each experiment, 1 × 10⁴ to 2 × 10⁴ responder cells were cultured with PHA (2 μg/mL) plus 1 × 10⁴ irradiated autologous ACs with or without IL-2 (10 U/mL, A); irradiated allogeneic PBMCs (B); soluble anti-CD3 with ACs (C); and soluble anti-CD3 with IL-2 (10 U/mL) in the presence of ACs (D). Conc indicates concentration. (E-F) Production of IL-2 (E) and IFN-γ (F) in the supernatants from the culture of CD4⁺CD25⁺ or CD4⁺CD25⁻(2 × 10⁴) cells stimulated with PHA for 3 days in the presence of autologous ACs.