title: IL-12 receptor. II. Distribution and regulation of receptor expression.
abstract: IL-12 is a heterodimeric lymphokine that induces IFN-gamma production by resting PBMC, enhances the lytic activity of NK/lymphokine activated killer cells, and causes the proliferation of activated T cells and NK cells. In this report, we have investigated the expression of IL-12R on mitogen- and IL-2-activated PBMC or tonsillar lymphocytes as well as on a variety of cell lines. The results of radiolabeled IL-12-binding assays indicated that high affinity IL-12R are present on PBMC activated by various T cell mitogens or by IL-2. High affinity IL-12R were also found to be expressed constitutively on a transformed marmoset NK-like cell line HVS.SILVA 40. At the time of peak IL-12R expression, mitogen- or IL-2-activated cells displayed approximately 1000 to 9000 IL-12 binding sites/cell with an apparent Kd of 100 to 900 pM. Kinetic studies revealed that maximum expression of IL-12R occurred earlier on PHA-activated PBMC as compared with PBMC activated by IL-2, and that expression of IL-12R on these cells correlated with their ability to proliferate in response to IL-12. Although IL-2 could up-regulate IL-12R expression on resting PBMC, the ability of mitogen-activated PBMC to up-regulate IL-12R was found to be independent of IL-2. Analysis of IL-12R expression by flow cytometry revealed that receptors for IL-12 are present on activated T cells of both the CD4+ and CD8+ subsets and on activated CD56+ NK cells. In contrast, neither resting PBMC or tonsillar B cells nor tonsillar B cells activated by anti-IgM/Dx, anti-IgM/Dx + IL-2, or SAC + IL-2 displayed IL-12R detectable by flow cytometry or by the radiolabeled IL-12-binding assay. In summary, these results indicate that activation of T cells or NK cells results in up-regulation of IL-12R expression; on the other hand, B cell activation, at least under some circumstances, appears not to be associated with enhanced expression of IL-12R.
authors.affiliation: Department of Immunopharmacology, Hoffmann-La Roche, Nutley, NJ 07110.
authors.forename: B B
authors.initials: BB
authors.lastname: Desai
authors.forename: P M
authors.initials: PM
authors.lastname: Quinn
authors.forename: A G
authors.initials: AG
authors.lastname: Wolitzky
authors.forename: P K
authors.initials: PK
authors.lastname: Mongini
authors.forename: R
authors.initials: R
authors.lastname: Chizzonite
authors.forename: M K
authors.initials: MK
authors.lastname: Gately
mesh_terms: D000818:Animals; D015704:CD4 Antigens / Q000032:analysis; D016827:CD8 Antigens / Q000032:analysis; D000001:Calcimycin / Q000494:pharmacology; D002460:Cell Line; D002478:Cells, Cultured; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism / Q000494:pharmacology; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000737:chemistry*; D010641:Phenotype; D010835:Phytohemagglutinins; D015375:Receptors, Interleukin-2 / Q000032:analysis*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D015704:CD4 Antigens; D016827:CD8 Antigens; D007376:Interleukin-2; D010835:Phytohemagglutinins; D015375:Receptors, Interleukin-2; D000001:Calcimycin; D013755:Tetradecanoylphorbol Acetate