Xenogeneic antiserum to soluble products from activated lymphoid cells inhibits interleukin 1-mediated functions in the helper pathway of cytolytic-effector-cell differentiation.

We have produced an antiserum that inhibits interleukin 1-mediated functions in immune responses. Skin graft-induced helper factor-containing supernatant (SgHFS) was used an immunogen in rats. The resultant antiserum was immunosuppressive of T-cell functions both in vivo and in vitro. We have further studied the effects of this antiserum on cell surface molecules that are involved in the generation of cytolytic effector T cells. Rat anti-SgHFS inhibited the differentiation of precytolytic effector cells in mixed lymphocyte cultures by blocking the helper-cell pathway. Both the level and the kinetics of interleukin 2 production were affected as the duration of rat anti-SgHFS pretreatment was increased. Interleukin 1 production after 24 hr in culture was unaffected. Monokines, including partially purified interleukin 1, actively compete with the rat anti-SgHFS by activating helper cells and thus circumvent suppression. Rat anti-SgHFS inhibits interleukin-1-mediated functions by a time-dependent active process. Thus, the target cell surface molecule(s) affected by the rat anti-SgHFS are associated with interleukin 1 function and may be the interleukin 1 receptor.