Role of interleukin-2 receptors in the suppressive effect of spleen cells from anti-CD3-treated mice

In the present study, we demonstrate that unresponsive spleen T cells from mice injected with a low dose of anti-CD3 mAb (single 10 micrograms i.v. injection) significantly inhibit Con A-induced proliferation of normal spleen cells. The induction of this phenomenon requires in vivo activation since spleen cells from mice injected with the F(ab')2 fragment of anti-CD3 mAb fail to promote it. Suppression of normal T cell proliferation is concomitant with increased expression of IL-2 receptor on spleen cells from anti-CD3-treated mice. It disappears within 3 days when IL-2R has returned to background levels. A normal proliferative response to Con A can be restored when high concentrations of IL-2 are added together with the "suppressor" cells. Taken together, these data support the notion that activated spleen cells from anti-CD3-injected mice exert their inhibitory effect by competing for the IL-2 generated during culture.