EXPRESSION OF HUMAN IL-1-ALPHA AND BETA-MESSENGER RNAS AND IL-1 ACTIVITY IN HUMAN PERIPHERAL-BLOOD MONONUCLEAR-CELLS

  • 1 January 1987
    • journal article
    • research article
    • Vol. 3  (5) , 255-265
Abstract
The macrophage-derived lymphokine interleukin 1 (IL 1) plays a critical role in modulating immune (cellular and humoral) and nonimmune responses. For example, the relative expression of IL 1.alpha. and .beta. under various states may be crucial to the success of the immune system in response to infection. Until recently, a comparative study of IL 1 mRNA expression and IL 1 biological activity was not possible. We have cloned both IL 1.alpha. and .beta. cDNAs and employed them as probes in Northern blot analysis to determine in mitogen-stimulated peripheral blood mononuclear cells and steady-state expression of their cognate mRNAs with respect to IL 1 activity. IL 1 was determined by the lymphocyte-activating factor (IL 1/LAF)and the mononuclear cell factor (IL 1/MCF) activities. In lectin-stimulated PBMC, maximum cell-associated activities were detected at 12 and 24 hr after stimulation whereas maximum extracellular activities appeared between 24-48 hr. In the same cultures, the kinetics of IL 1 mRNA steady-state expression were determined by Northern gel blot analysis with IL 1.alpha. and .beta. cDNA probes. IL 1 mRNAs were undetectable in noncultured freshly isolated PBMC (time zero). Both IL 1 mRNAs appeared as early as 4 hr after lectin stimulation as did IL 1.beta. mRNA in unstimulated cultures. Both IL 1.alpha. and .beta. mRNA steady-state levels were barely detectable by 48 hr. At all time points, IL 1 mRNA levels were considerably lower in unstimulated cultures. IL 1.beta. mRNA was always considerably more abundant than IL 1.alpha. mRNA. The less abundant IL 1.alpha. mRNA showed a decrease in its steady-state levels prior to the reduction in the levels of IL 1.beta. mRNA. TNF.alpha. activity and mRNA were not detected under these culture conditions. Poly(A)+RNA injected into Xenopus oocytes revealed that the Northern blot detected IL 1 mRNAs were biologically active. To understand the precise nature of IL 1 in immune and nonimmune events, we felt it necessary to first study the kinetics of IL 1 mRNA steady-state levels with respect to this cell-associated and extracellular biological activities. The data presented here may allow for a better uinderstanding of the etiology of various immune and nonimmune responses that are modulated thorugh the expression of IL 1.