Interleukin 1 can replace the requirement for I-A-positive cells in the proliferation of antigen-primed T cells.

Abstract

Antigen-primed mouse T cells require I-region-compatible adherent cells and the priming antigen to proliferate in vitro. The Ia-recognition event appears to be required for the T cell to induce secretion of the monokine interleukin 1 (IL 1) from adherent cells; the conventionally held views is that Ia is directly required for T cell activation. IL 1 could replace the requirement for Ia+ cells in T cell proliferation assess in vitro. To test this prediction, keyhole limpet hemocyanin (KLH)-primed C57BL/6 mouse lymph node cells were depleted of I-A+ cells by treating with monoclonal anti-I-Ab and complement. As expected, this treatment eliminated the ability of KLH to provoke a proliferative response by primed T cells. Proliferation was restored by providing exogenous IL 1, but only in conjunction with added KLH. The proliferative response of primed T cells could also be blocked by adding anti-I-Ab to culture, and this inhibition could similarly be reversed by providing IL 1 in the presence of the specific antigen KLH. A model of T cell activation was proposed and its implications were discussed.