Increased natural killer cell activities in patients treated with gonadotropin releasing hormone agonist

Natural killer (NK) cell activity in patients treated with gonadotropin-releasing hormone agonists (GnRH-a) was studied. The subjects were 8 patients with endometriosis (6 with ovarian endometrial cyst, 2 with adenomyosis) and 3 patients with uterine leiomyoma. Changes in serum estradiol (E2) concentration and NK cell activity in peripheral blood were analyzed before and after GnRH-a treatment (buserelin 900 microg/day for 4-5 months). NK cell activity was determined by 51Cr release assay and E2 by radioimmunoassay. NK cell activity before GnRH-a treatment was 37.7 +/- 19.0%, and after therapy activity increased significantly to 50. 8 +/- 18.2%. However, no significant correlation between the increase in NK cell activity and the decrease in E2 concentration was found. Results indicate that the standard GnRH-a treatment for endometriosis and uterine leiomyoma might increase NK cell activity. The etiology of the increase of NK activity with GnRH-a treatment is likely related to factors other than E2 concentration.