Studies ofaninterleukin 1inhibitor: characterization andclinical significance

SUMMARY Supernatants from24hcultures ofhumanperipheral blood mononuclear cells (PBMNC) werefractionated andtested forinterleukin (IL-1) activity inthemousethymocyte assay withphytohaemagglutinin (PHA).Bytheaddition ofindividual supernatant fractions together withpartially purified IL-Itothethymocyte assay, wedemonstrate thepresence ofstrong inhibitory activity withamol.wtof5,000-9,000 andanisoelectric point of4556.Theactivity isbothheat(56C)andacid(pH15)resistant. Thisinhibitor hasno detectable suppressive effect onoptimal andsuboptimal concanavalin A (ConA), pokeweed mitogen (PWM),andPHA responses ofPBMNC.Theaction oftheinhibitor appears tobespecifically directed against IL-Iaction onthymocytes andhasnoinhibitory effect oninterleukin 2(IL-2) activity. Thefindings showthat adherent PBMNC produce bothIL-1andafactor whichopposes IL-1action onthymocytes butnotonperipheral (mature) Tcells. Thisfactor mayregulate Tcell maturation, activation, andproliferation.