title: Cyclosporin-A inhibits IL-2 production by all human T-cell clones having this function, independent of the T4/T8 phenotype or the coexpression of cytolytic activity.
abstract: Cyclosporin A (CsA) is an immunosuppressive drug that acts, at least in part, by blocking IL-2 release. Since IL-2-producing human T cells are heterogeneous with respect to their functional capabilities and surface phenotype, we investigated whether differences in sensitivity to CsA existed among different IL-2-producing T-cell clones. Preliminary dose/response experiments showed that 100 ng/ml CsA completely inhibited the PHA- or OKT3-induced IL-2 production by four representative T4+/T8- clones. On the other hand, this drug concentration had virtually no inhibitory effect on the proliferation of CTL-L murine indicator cells to exogeneous IL-2. Clones were derived directly from peripheral blood by applying a microculture system that allows clonal expansion of essentially all T cells: under these experimental conditions growing clones are therefore highly representative of the starting T-cell populations. Among clones so derived, 28 were selected according to their capability to release IL-2 upon PHA stimulation. Six of such clones displayed cytolytic activity in a PHA-dependent assay against P815 murine target cells. CsA (100 ng/ml) abrogated IL-2 production of all clones, including those displaying cytolytic activity and expressing the T4-/T8+ phenotype.
mesh_terms: D002999:Clone Cells; D003524:Cyclosporins / Q000494:pharmacology*; D003602:Cytotoxicity, Immunologic; D006801:Humans; D007376:Interleukin-2 / Q000096:biosynthesis*; D010641:Phenotype; D010835:Phytohemagglutinins / Q000494:pharmacology; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*
chemical_list: D003524:Cyclosporins; D007376:Interleukin-2; D010835:Phytohemagglutinins