title: Analysis of the mechanisms of human cytotoxic T lymphocyte response inhibition by NO.
abstract: NO is a potent cellular mediator which has been shown to modulate several immune mechanisms. Using human T lymphocytes as responder cells in a primary mixed lymphocyte reaction, we demonstrated that, at the initiation of the culture, exogenously provided NO via sodium nitroprusside, in non-toxic concentrations, inhibited both allogeneic proliferative and primary cytotoxic responses in a dose-dependent manner. In contrast, it had no effect on the cytotoxic activity of established human TCR (alpha)beta and TCR (gamma)delta cytotoxic T lymphocyte (CTL) clones. The NO inhibitory effect on primary cytotoxic T cell response correlates with inhibition of T cell blastogenesis. Furthermore, under our stimulation conditions, NO induced an inhibition of IL-2 production, an alteration of IL-2R(alpha) expression, and a down-regulation of NF-AT translocation in CD4(+) and CD8(+)allostimulated T cells. Furthermore, we demonstrate that the inhibition of allospecific CTL activity by the NO donor was at least in part related to an inhibition of granzyme B and Fas ligand transcription as revealed respectively by RNase protection and RT-PCR analysis. These results suggest that NO may function to fine tune human CD3(+) T cell activation and subsequent CTL generation.
mesh_terms: D000328:Adult; D004268:DNA-Binding Proteins / Q000378:metabolism; D053222:Fas Ligand Protein; D053804:Granzymes; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis; D007376:Interleukin-2 / Q000096:biosynthesis; D008213:Lymphocyte Activation; D008562:Membrane Glycoproteins / Q000235:genetics; D050778:NFATC Transcription Factors; D009569:Nitric Oxide / Q000502:physiology*; D009599:Nitroprusside / Q000494:pharmacology; D009687:Nuclear Proteins; D015375:Receptors, Interleukin-2 / Q000032:analysis; D012697:Serine Endopeptidases / Q000235:genetics; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects / Q000276:immunology*; D014157:Transcription Factors / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
chemical_list: D004268:DNA-Binding Proteins; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D007376:Interleukin-2; D008562:Membrane Glycoproteins; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D015375:Receptors, Interleukin-2; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D009599:Nitroprusside; D009569:Nitric Oxide; D007371:Interferon-gamma; C509213:GZMB protein, human; D053804:Granzymes; D012697:Serine Endopeptidases