title: Anergic T-lymphocyte clones have altered inositol phosphate, calcium, and tyrosine kinase signaling pathways.
abstract: Full activation of TH1 helper T lymphocytes requires ligation of the specific T-cell antigen receptor (TCR) and a second signal provided by costimulator molecule(s) expressed on particular antigen-presenting cells. Stimulation via the TCR complex alone generates a subsequent unresponsive state characterized by an inability to produce interleukin 2. We report here that such anergic cells exhibit multiple alterations in TCR-associated signaling. The basal levels of intracellular free calcium and phosphatidylinositol 1,4,5-trisphosphate are elevated in anergic cells, and the levels fail to increase significantly upon subsequent restimulation. Examination of phospholipase C-gamma 1 reveals evidence for post-translational modification, correlating with increased tyrosine phosphorylation of the molecule. Tyrosine phosphorylation of additional substrates identified from whole-cell lysates also is altered compared to untreated cells, suggesting a modification in net tyrosine kinase activity. Although the level of kinase activity present in TCR/CD3 or Lck immunoprecipitates is modestly altered after induction of anergy, there is a dramatic increase in specific Fyn-associated tyrosine kinase activity in anergic cells and increased phosphorylation of a 110-kDa protein that is coimmunoprecipitated with Fyn. These results are consistent with a model in which anergic TH1 lymphocytes display a fundamental alteration in TCR-mediated tyrosine kinase activity, associated with changes in phospholipase C-gamma 1, inositol phosphates, and intracellular free calcium.
authors.affiliation: Department of Pathology, University of Chicago, IL 60637.
authors.forename: T F
authors.initials: TF
authors.lastname: Gajewski
authors.forename: D
authors.initials: D
authors.lastname: Qian
authors.forename: P
authors.initials: P
authors.lastname: Fields
authors.forename: F W
authors.initials: FW
authors.lastname: Fitch
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002999:Clone Cells; D007108:Immune Tolerance; D007295:Inositol Phosphates / Q000378:metabolism*; D007371:Interferon-gamma / Q000096:biosynthesis; D007376:Interleukin-2 / Q000096:biosynthesis; D007377:Interleukin-3 / Q000096:biosynthesis; D051379:Mice; D008811:Mice, Inbred DBA; D010750:Phosphoproteins / Q000378:metabolism; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011948:Receptors, Antigen, T-Cell / Q000502:physiology; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000502:physiology*; D006377:T-Lymphocytes, Helper-Inducer / Q000502:physiology*; D010738:Type C Phospholipases / Q000378:metabolism; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D007295:Inositol Phosphates; D007376:Interleukin-2; D007377:Interleukin-3; D010750:Phosphoproteins; D011948:Receptors, Antigen, T-Cell; D019000:Phosphotyrosine; D014443:Tyrosine; D007371:Interferon-gamma; D011505:Protein-Tyrosine Kinases; D010738:Type C Phospholipases; D002118:Calcium