title: Interleukin 1-dependent induction of both interleukin 2 secretion and interleukin 2 receptor expression by thymoma cells.
abstract: The macrophage-derived product, interleukin 1 (IL 1) is thought to play an important regulatory role in the proliferation of T lymphocytes; however, its mechanism of action is unknown. We describe in this report a variant subline of EL4 thymoma cells (EL4-6.1) that displays a high degree of responsiveness to IL 1. We show that recombinant IL 1 can induce both the secretion of interleukin 2 (IL 2) and the expression of IL 2 receptors (IL 2-R) by these cells. EL4-6.1 cells do not constitutively secrete IL 2, nor do they express IL 2-R; but when cultured in the presence of recombinant IL 1, they secrete detectable amounts of IL 2 (5 to 15 U/ml). In the presence of either suboptimal levels of phorbol ester (PMA) or Ionomycin, the addition of IL 1 resulted in up to an 80-fold enhancement in the amount of IL 2 secreted. Stimulation with IL 1 alone or in combination with Ionomycin was unable to induce detectable IL 2-R expression by EL4-6.1 cells. However, in the presence of suboptimal concentrations of PMA, IL 1 induced expression of about 3000 high affinity (dissociation constant, Kd of 31 pM) and 50,000 low affinity (Kd of 2800 pM) IL 2-R. These IL 2-R were functional, based on their ability to rapidly internalize IL 2. This model system will allow a detailed analysis of the mechanisms involved in the regulation of the immune response by IL 1 and IL 2.
mesh_terms: D000818:Animals; D002460:Cell Line; D004306:Dose-Response Relationship, Immunologic; D007375:Interleukin-1 / Q000502:physiology*; D007376:Interleukin-2 / Q000096:biosynthesis* / Q000378:metabolism; D007700:Kinetics; D008213:Lymphocyte Activation; D051379:Mice; D011971:Receptors, Immunologic / Q000096:biosynthesis*; D015375:Receptors, Interleukin-2; D013601:T-Lymphocytes / Q000378:metabolism; D013945:Thymoma / Q000378:metabolism*
chemical_list: D007375:Interleukin-1; D007376:Interleukin-2; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2