title: Interleukin-12 differentially regulates expression of IFN-gamma and interleukin-2 in human T lymphoblasts.
abstract: Interleukin-12 (IL-12) is known to upregulate expression of interferon-gamma (IFN-gamma) by activated T cells. However, the effects of IL-12 on production of other Th1-type cytokines are less well defined. In this study, we examined the effects of IL-12 on expression of several cytokines, including IFN-gamma, IL-2, tumor necrosis factor-alpha (TNF-alpha), and IL-10, by primary human CD3(+) T cells. Although purified resting T cells were largely nonresponsive to IL-12 stimulation, anti-CD3-activated T cell blasts were strongly responsive, as demonstrated by the ability of IL-12 to induce Stat4 DNA-binding activity. Restimulation of T lymphoblasts on immobilized anti-CD3 monoclonal antibodies (mAb) induced rapid expression of TNF-alpha mRNA and more gradual increases in mRNA levels for IL-2, IFN-gamma, and IL-10. IL-12 markedly upregulated expression of IFN-gamma and IL-10 but downregulated expression of IL-2 in a dose-dependent and time-dependent manner. The levels of IL-2 produced by IL-12-treated T cells correlated inversely with the levels of IL-10. Moreover, neutralization of IL-10 activity with anti-IL-10 antibodies normalized IL-2 production by IL-12-treated T cells, confirming that the inhibition of IL-2 production by IL-12 was IL-10 mediated. Thus, IL-12 amplified expression of IFN-gamma and IL-10 and, via its ability to upregulate production of IL-10, inhibited expression of IL-2. These findings demonstrate that IL-12 differentially regulates expression of the Th1-type lymphokines, IFN-gamma and IL-2, in T lymphoblasts.
authors.affiliation: Division of Cytokine Biology, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892, USA.
authors.forename: H L
authors.initials: HL
authors.lastname: Dickensheets
authors.forename: S L
authors.initials: SL
authors.lastname: Freeman
authors.forename: R P
authors.initials: RP
authors.lastname: Donnelly
mesh_terms: D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000096:biosynthesis; D015536:Down-Regulation / Q000276:immunology; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis*; D016753:Interleukin-10 / Q000096:biosynthesis / Q000502:physiology; D018664:Interleukin-12 / Q000502:physiology*; D007376:Interleukin-2 / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D008213:Lymphocyte Activation; D050797:STAT4 Transcription Factor; D015398:Signal Transduction / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D015534:Trans-Activators / Q000096:biosynthesis; D015854:Up-Regulation / Q000276:immunology
chemical_list: D004268:DNA-Binding Proteins; D007376:Interleukin-2; D050797:STAT4 Transcription Factor; C494090:STAT4 protein, human; D015534:Trans-Activators; D016753:Interleukin-10; D018664:Interleukin-12; D007371:Interferon-gamma