EXPRESSION OF INTERLEUKIN-1-ALPHA AND BETA-GENES BY HUMAN BLOOD POLYMORPHONUCLEAR LEUKOCYTES

Expression of IL-1-alpha and beta-genes was studied in human blood PMN with close monitoring of the effects of contaminating mononuclear leukocytes (MNL). We provide evidence that PMN both transcribe and translate IL-1-alpha and beta-genes after stimulation with LPS or IL-1-alpha. A combination of mouse thymocyte comitogen proliferation assay, ELISA, and immunocytochemistry was required to establish that IL-1-alpha and beta-synthesis observed in preparations of PMN could not be accounted for by the low level of contaminating MNL. Synthesis of IL-1-beta in PMN exceeded that of IL-1-alpha, but little or no IL-1-alpha was released by PMN. Although increases in IL-1 mRNA after stimulation of PMN and MNL with LPS were similar, PMN were less efficient than MNL in translating IL-1 mRNA. In contrast, PMN and MNL IL-1-alpha and beta-mRNAs were translated with equal efficiency in rabbit reticulocyte lysates, suggesting that synthesis of IL-1 in PMN is subject to some form of translational control. We conclude that PMN stimulated with LPS efficiently transcribe but inefficiently translate IL-1 genes relative to MNL. IL-1-beta-transcription and translation predominates over that of IL-1-alpha, and IL-1-beta is the predominant IL-1 protein released by PMN. IL-1 can induce its own synthesis in PMN.