title: Selective proliferation of gamma delta T lymphocytes exposed to high doses of ionomycin.
abstract: The alpha beta T cell repertoire is primarily shaped in the thymus. However, extrathymic positive selection has been demonstrated for many gamma delta T cell clonotypes. This latter type of selection is the result of a peripheral clonal expansion which could be facilitated by special physiological properties of gamma delta T cells, distinguishing them from most alpha beta T cells. In studying the behavior of T cells under conditions of polyclonal activation, we noticed a differential sensitivity between alpha beta and gamma delta T cells to strong stimulatory signals. When induced with high doses of ionomycin, a large fraction of peripheral gamma delta T cells and a small fraction of alpha beta T cells are able to proliferate exponentially while most alpha beta T cells die. This phenomenon appears to be related to intracellular regulation of high concentrations of cytosolic Ca2+. The ability to proliferate under strong stimulatory conditions is a striking feature of many peripheral gamma delta T cells but not of gamma delta thymocytes. In general, T cells selected in the periphery by clonal expansion might be characterized by resistance to strong stimuli and typically, by their ability to "handle" higher concentrations of free cytoplasmic calcium.
authors.affiliation: Department of Medicine, National Jewish Center for Immunology and Respiratory Medicine, Denver, CO 80206.
authors.forename: R
authors.initials: R
authors.lastname: Rajasekar
authors.forename: A
authors.initials: A
authors.lastname: Augustin
mesh_terms: D000818:Animals; D015704:CD4 Antigens / Q000032:analysis; D016827:CD8 Antigens / Q000032:analysis; D002118:Calcium / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D003593:Cytoplasm / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015334:Gene Rearrangement, gamma-Chain T-Cell Antigen Receptor; D015759:Ionomycin / Q000008:administration & dosage*; D008198:Lymph Nodes / Q000166:cytology; D008213:Lymphocyte Activation / Q000187:drug effects*; D051379:Mice; D008807:Mice, Inbred BALB C; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000235:genetics / Q000378:metabolism*; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism
chemical_list: D015704:CD4 Antigens; D016827:CD8 Antigens; D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta; D015759:Ionomycin; D002118:Calcium