ANTIBODIES DIRECTED AT MOUSE IL-2-R ALPHA-CHAINS AND BETA-CHAINS ACT IN SYNERGY TO ABOLISH T-CELL PROLIFERATION IN-VITRO AND DELAYED-TYPE HYPERSENSITIVITY REACTION IN-VIVO

The anti-mouse IL-2-R beta chain mAb TM-beta 1 which by itself, does n ot affect IL-2-dependent proliferation through the high affinity mouse IL-2 receptor, was shown to cooperate in a synergistic way with a set of anti-IL-2-R alpha chain mAbs both in vitro and in vivo. In vitro, when associated at equimolar concentrations, the TM-beta 1/anti-alpha mAb association was four to ten times more efficient at inhibiting the proliferation of the CTL-L2 cell lint than was a similar concentratio n of anti-alpha mAb alone. In addition, a bispecific antibody in which a Fab' fragment of TM-beta 1 was covalently linked to a Fab' fragment of one of the anti-alpha mAb (5A2) was shown to be as efficient as th e TM-beta 1/5A2 association. The association of TM-beta 1 with 5A2 was also tested in vivo in a sheep red blood cell-induced delayed type hy persensitivity (DTH) model. TM-beta 1 which. by itself, had no effect on DTH, induced a two- to threefold decrease in the doses of 5A2 requi red to suppress this cell-mediated immune reaction.