title: Expression of functional IL 2 receptors by lipopolysaccharide and interferon-gamma stimulated human monocytes.
abstract: Human peripheral blood monocytes were stimulated with lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma) alone or in combination. Stimulated but not resting monocytes displayed the Tac peptide of the interleukin 2 (IL 2) receptor within 24 hr as measured by immunofluorescence staining and [3H] Tac binding. The total number of anti-Tac binding sites on co-stimulated monocytes was 13,700. By using scatchard analysis with radiolabeled IL 2, the activated cells were shown to express low numbers (below 100 sites/cell) of high affinity binding sites with a KD of approximately 15 pM. LPS and IFN-gamma were additive in augmenting the number of IL 2 and anti-Tac binding sites. By using an ELISA assay specific for the soluble released form of the Tac peptide we identified 112 U/ml of IL 2 receptors in the supernatant of monocytes stimulated for 24 hr with IFN-gamma, 233 U/ml after stimulation with LPS, and 519 U/ml after the addition of both stimulating agents. Both the membrane form (55,000 daltons), as well as the soluble form (45,000 to 50,000 daltons) of the Tac, IL 2 receptor, peptide from monocytes were shown by immunoprecipitation and gel electrophoresis to be similar size to the comparable forms of these receptors derived from activated T cells. In addition, monocytes stimulated for 8 hr contained mRNA specifically hybridizing to a cDNA probe coding for the Tac peptide. Finally, activated monocytes responded to the addition of recombinant IL 2 by an increase in H2O2 production that was measured by using fluorescent indicator 2,7-dichlorofluorescein. This response as well as the observed induction of monocytic IL 2 receptors by LPS may point to a functional role for this receptor during monocyte/macrophage responses to microbial infections.
mesh_terms: D002453:Cell Cycle / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000502:physiology; D007371:Interferon-gamma / Q000494:pharmacology*; D007376:Interleukin-2 / Q000502:physiology*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D009000:Monocytes / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D011971:Receptors, Immunologic / Q000502:physiology*; D015375:Receptors, Interleukin-2; D012995:Solubility
chemical_list: D007376:Interleukin-2; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2; D007371:Interferon-gamma; D006861:Hydrogen Peroxide