Inhibition of human natural killer cell activity by the protein kinase C inhibitor 1-(5-isoquinolinesulfonyl)-2-methylpiperazine is an early but post-binding event.
Recent evidence has demonstrated a protein kinase C (PKC)-dependent step in cytotoxic T lymphocyte activation. Here, we examined the influence of PKC in the lytic response of human NK cells to K562, an NK-sensitive tumor target cell. We used the known protein kinase inhibitors 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (H-7) and HA1004. H-7 caused a dose-related inhibition of NK cell-mediated cytolysis (CMC) when the inhibitor was present throughout the course of the 3-h chromium release assay. The 50% inhibitory concentration for H-7 was 7 microM. In contrast, HA1004, which exerts a greater inhibitory effect on cyclic nucleotide-dependent protein kinases than PKC, had no effect on NK-CMC. The suppression of NK-CMC by H-7 was not due to inhibition of binding of the effector cells to target cells and could be reversed by the addition of PMA. H-7 was most effective in abrogating NK-CMC when added to the assay within the first 30 min and treatment of the effector and target cells with H-7 resulted in no loss of NK-CMC. Because nearly 50% of the normal NK lytic activity had taken place by 30 min, this suggested that H-7 inhibited an early event. H-7 exerted a dose-related suppression of antibody-dependent cell-mediated cytotoxicity (ADCC) suggesting that NK-CMC and ADCC share the utilization of PKC, however, HA1004 did not inhibit ADCC. Treating NK cells with IL-2 or IFN-beta did not overcome the inhibition of NK-CMC by H-7. In this study, we have thus demonstrated the presence of a PKC-dependent step in NK-CMC and ADCC.
Steele
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TA
Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis 46223.
Brahmi
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D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000328:Adult; D000920:Antibody-Dependent Cell Cytotoxicity / Q000187:drug effects; D001667:Binding, Competitive / Q000187:drug effects; D003601:Cytotoxicity Tests, Immunologic; D003602:Cytotoxicity, Immunologic / Q000187:drug effects*; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D007370:Interferon Type I / Q000494:pharmacology; D007376:Interleukin-2 / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology*; D007694:Killer Cells, Natural / Q000187:drug effects* / Q000201:enzymology / Q000276:immunology; D007700:Kinetics; D008213:Lymphocyte Activation / Q000187:drug effects*; D010879:Piperazines / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors*; D013449:Sulfonamides; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D007166:Immunosuppressive Agents; D007370:Interferon Type I; D007376:Interleukin-2; D007546:Isoquinolines; D010879:Piperazines; D013449:Sulfonamides; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; C043204:N-(2-guanidinoethyl)-5-isoquinolinesulfonamide; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate