Constitutive active p21ras enhances primary T cell responsiveness to Ca2+ signals without interfering with the induction of clonal anergy.
Chronic engagement of the T cell receptor mediates the induction of T lymphocyte unresponsiveness called clonal anergy. The development of such unresponsiveness has been suggested as one of the mechanisms that regulate peripheral tolerance to self-antigens and hamper the capacity of tumor antigen-specific T cells to eliminate cancerous cells. In the attempt to enhance the effector function of CD4(+) T lymphocytes and their resistance to clonal anergy induction, we have transduced primary T cells with a retroviral vector encoding active p21(ras) (Ras(Leu61)). Here we show that Ras(Leu61) elicited TCR-independent activation of the Ras-Raf-ERK pathway and conferred primary T cells with the ability to secrete IL-2 in response to stimulation with a Ca(2+) ionophore alone, without altering antigen-, CD3/CD28- and PMA/ionomycin-driven IL-2 secretion and T cell proliferation in vitro. However, chronic engagement of the TCR onthe surface of Ras(Leu61) T cells still led to an inability of the cells to produce IL-2 upon restimulation. These results indicate that enforced p21(ras) functionality enhances primary T cells responses to calcium-generated signals, but is insufficient to prevent TCR-driven T cell unresponsiveness and suggest that additional biochemical mechanisms, independent of p21(ras), negatively regulate IL-2 production in unresponsive T cells.
Crespi
Daniela
D
Cancer Immunotherapy and Gene Therapy Program, DIBIT/H. S. Raffaele, Milan, Italy.
Massa
Stefania
S
Basso
Veronica
V
Colombetti
Sara
S
Mueller
Daniel L
DL
Mondino
Anna
A
D000818:Animals; D002070:Butadienes / Q000494:pharmacology; D017252:CD3 Complex / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D020013:Calcium Signaling; D017635:Clonal Anergy; D004791:Enzyme Inhibitors / Q000494:pharmacology; D011905:Genes, ras; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism; D015759:Ionomycin / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects; D048369:MAP Kinase Kinase 1; D051379:Mice; D008807:Mice, Inbred BALB C; D008822:Mice, Transgenic; D019950:Mitogen-Activated Protein Kinase 1 / Q000502:physiology; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology; D008979:Moloney murine leukemia virus / Q000235:genetics; D009570:Nitriles / Q000494:pharmacology; D010047:Ovalbumin / Q000276:immunology; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000502:physiology; D019908:Proto-Oncogene Proteins c-raf / Q000502:physiology; D016283:Proto-Oncogene Proteins p21(ras) / Q000502:physiology*; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D011993:Recombinant Fusion Proteins / Q000502:physiology; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014162:Transfection
D002070:Butadienes; D017252:CD3 Complex; D004791:Enzyme Inhibitors; D007376:Interleukin-2; D009570:Nitriles; D011948:Receptors, Antigen, T-Cell; D011993:Recombinant Fusion Proteins; C113580:U 0126; D015759:Ionomycin; D010047:Ovalbumin; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; C482125:MAP2K1 protein, human; C482127:Map2k1 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras); D013755:Tetradecanoylphorbol Acetate