Granzyme B is not required for T_reg cell–mediated suppression of ConA-activated and alloactivated T_eff-cell proliferation in vitro. (A) Suppression of CD4⁺CD25⁻ T_eff-cell proliferation stimulated by ConA in the presence of syngeneic T cell–depleted, irradiated APCs. (B) Representative flow plot of granzyme B expression, gated on wild-type T_reg cells cultured for 3 days with ConA-activated T_eff cells under maximal suppression conditions (1:1). (C) Dose-dependent suppression of 129/SvJ CD4⁺CD25⁻ T_eff-cell proliferation stimulated by fully mismatched Balb/c T cell–depleted APCs. (D) Representative flow plot of granzyme B expression, gated on wild-type T_reg cells cultured for 5 days with alloactivated T_eff cells under maximal suppression conditions (1:1). All data shown are representative of 3 independent experiments.