title: Functional and biochemical characterization of a calcium-ionophore-induced state of unresponsiveness in a cytolytic T cell clone.
abstract: To characterize the requirements for the induction of an anergic state in immunocompetent cells we examined the effect of an increase in intracellular calcium concentration on the subsequent responsiveness of cytolytic T cells to antigenic stimulation in vitro. Pretreatment of a murine cytolytic T cell clone with the calcium-ionophore A23187 resulted in the induction of an anergic state characterized by a decrease in cytolytic activity and granule exocytosis upon Ag-specific stimulation. Furthermore, IFN-gamma synthesis declined whereas de novo synthesis of a yet unidentified protein with a molecular mass of 33 kDa as well as proliferative response of cells in response to exogenous IL-2 were unaffected. This state of partial unresponsiveness 1) could be prevented by concomitant pretreatment of cells with cyclosporin A or protein synthesis inhibitors and 2) was reversible within 48 h. Biochemical analysis of TCR-induced intracellular activation revealed a block in signal transduction before the activation of protein kinase C because cellular unresponsiveness could be bypassed by the phorbol ester PMA plus the calcium-ionophore A23187. However, phosphatidylinositol turnover was markedly inhibited in unresponsive cells that also did not show a calcium influx on stimulation with concanavalin A. We conclude that a rise in intracellular calcium in cytolytic T cells might not only be necessary for cellular activation but may also trigger the induction of a partial unresponsiveness to antigenic stimulation due to an inhibition in the early phase of signal transduction.
authors.affiliation: Division of Hematology, University of Essen, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Trenn
authors.forename: J
authors.initials: J
authors.lastname: Sykora
authors.forename: M C
authors.initials: MC
authors.lastname: Michel
authors.forename: G
authors.initials: G
authors.lastname: Brittinger
mesh_terms: D000001:Calcimycin / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D002999:Clone Cells; D003513:Cycloheximide / Q000494:pharmacology; D016572:Cyclosporine / Q000494:pharmacology; D005089:Exocytosis; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects; D010716:Phosphatidylinositols / Q000378:metabolism; D011506:Proteins / Q000032:analysis; D011948:Receptors, Antigen, T-Cell / Q000032:analysis; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects* / Q000502:physiology
chemical_list: D007376:Interleukin-2; D010716:Phosphatidylinositols; D011506:Proteins; D011948:Receptors, Antigen, T-Cell; D000001:Calcimycin; D016572:Cyclosporine; D003513:Cycloheximide; D002118:Calcium