In vitro effect of gonadotropin-releasing hormone agonist on natural killer cell cytolysis in women with and without endometriosis

Objective: The purpose of this study was to assess the in vitro effect of gonadotropin-releasing hormone agonist on natural killer cell activity in women with and without endometriosis and to ascertain whether gonadotropin-releasing hormone agonist effects on natural killer cell activity are direct or mediated solely through the hypoestrogenic state that they produce in vivo. Study design: With use of a chromium 51 release microcytotoxicity assay with K562 target cells, natural killer cell activity was measured after the incubation of mononuclear cells with leuprolide acetate that was obtained from 16 patients with endometriosis and 11 control subjects. Results: The cytotoxicity of natural killer cells that were obtained from patients with endometriosis was reduced significantly (P<.001) with leuprolide. Natural killer cell cytotoxicity from control patients was also significantly decreased (P=.005) with gonadotropin-releasing hormone agonist. Natural killer cell cytotoxicity was significantly lower in patients with endometriosis than in control patients (P=.029). Conclusion: These findings suggest a direct immunomodulatory role of gonadotropin-releasing hormone agonist on natural killer cell activity and confirm previous findings that patients with endometriosis have reduced natural killer cell cytotoxicity. (C) 2004 Elsevier Inc. All rights reserved.