title: Selective induction of p38 mitogen-activated protein kinase activity following A6H co-stimulation in primary human CD4(+) T cells.
abstract: We have recently described the novel A6H antigen expressed on human peripheral blood T cells and on renal cell carcinoma cells. Cross-linking of the A6H antigen results in co-stimulation of human CD4(+) T cells, characterized by induction of the transcription factor activator protein-1 (AP-1), proliferation and prominent IFN-gamma production, but low levels of IL-2. The proximal signaling events associated with A6H ligation include protein tyrosine kinase phosphorylation and association of p56 Lck, ZAP-70 and the TCR zeta chain. In this study we show that A6H co-stimulation selectively induced activation of the p38 mitogen-activated protein kinase (MAPK) pathway, whereas no significant c-Jun N-terminal kinases (JNK) activity was observed. In contrast, CD28 co-stimulation resulted in both p38 and JNK MAPK activities. Human CD4(+) T cells co-stimulated with A6H up-regulated AP-1 binding proteins reactive with a proximal AP-1 binding site in the human IFN-gamma promoter and a consensus AP-1 binding site. Moreover, preincubation of the T cells with the specific p38 MAPK inhibitor SB203580 resulted in decreased AP-1 binding following A6H or CD28 co-stimulation. This suggests that the p38 MAPK pathway is required for induction of full AP-1 binding activity in human CD4(+) T cells co-stimulated with A6H or CD28. Blocking the p38 MAPK pathway by SB203580 completely inhibited IFN-gamma production from A6H co-stimulated T cells and radically reduced IFN-gamma production from T cells co-stimulated with anti-CD28. In contrast, no significant inhibition of IL-2 production was seen after blocking of the p38 MAPK in either A6H or CD28 co-stimulated T cells. Since the p38 MAPK recently has been shown to be critically involved in regulation of IFN-gamma production from T(h)1 cells, we propose that A6H co-stimulation induces a specific pathway, mediated via p38 and AP-1 activation, for induction of a T(h)1 profile in human CD4(+) T cells.
authors.affiliation: BMC Immunobiology, Department of Tumor Immunology, University of Lund, Sölvegatan 21, 223 62 Lund, Sweden.
authors.forename: T
authors.initials: T
authors.lastname: Labuda
authors.forename: A
authors.initials: A
authors.lastname: Sundstedt
authors.forename: M
authors.initials: M
authors.lastname: Dohlsten
mesh_terms: D000951:Antigens, Neoplasm / Q000276:immunology*; D001665:Binding Sites; D018106:CD28 Antigens / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000201:enzymology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics; D002455:Cell Division; D002478:Cells, Cultured; D016384:Consensus Sequence; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D007371:Interferon-gamma / Q000096:biosynthesis / Q000235:genetics; D048031:JNK Mitogen-Activated Protein Kinases; D008213:Lymphocyte Activation; D020935:MAP Kinase Signaling System; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016853:Muromonab-CD3 / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D011725:Pyridines / Q000494:pharmacology; D018417:Th1 Cells / Q000166:cytology* / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014158:Transcription, Genetic; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: C119623:A6H antigen; D000951:Antigens, Neoplasm; D018106:CD28 Antigens; D004791:Enzyme Inhibitors; D007093:Imidazoles; D016853:Muromonab-CD3; D011725:Pyridines; D018808:Transcription Factor AP-1; D007371:Interferon-gamma; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580