Specific inhibition of interleukin 1 beta gene expression by an antisense oligonucleotide: obligatory role of interleukin 1 in the generation of lymphokine-activated killer cells

Abstract

The purpose of the studies reported here is to determine whether interleukin 1 (IL-1) plays an important role in the regulation of lymphokine-activated killer (LAK) cell induction. The addition of exogenous IL-1 to peripheral blood lymphocyte culture containing suboptimal concentrations of interleukin 2 (IL-2) resulted in induction of cytoplasmic pore-forming protein expression. Polymerase chain reaction results revealed that the mRNAs of both IL-1 alpha and IL-1 beta were induced within 6 h when cultured in IL-2 alone or in a combination of IL-2 and IL-1; however, tumor necrosis factor alpha and beta mRNAs were expressed earlier in peripheral blood lymphocytes stimulated with the combination of IL-1 and IL-2. Furthermore, we have examined the functional role of endogenous IL-1 in LAK activity. The lytic potential was significantly inhibited by an IL-1 receptor antagonist, which could block IL-1-mediated effects, or by specific neutralizing antibodies for IL-1, suggesting that the extracellular autocrine/paracrine pathway of IL-1 is involved in LAK activation. However, a synthetic IL-1 beta antisense oligonucleotide, which could specifically inhibit intracellular IL-1 beta protein expression as detected by Western blot, was more effective in reducing LAK killing, but it could not suppress the cytotoxicity generated by exogenous IL-1 plus IL-2. These findings clearly indicate the existence of an intracellular IL-1 autocrine circuit. Taken together, our results strongly indicate that IL-1 should be considered an obligatory factor in the regulation of IL-2-mediated lymphocyte functions.