EFFECT OF ESTROGEN REPLACEMENT THERAPY ON NATURAL-KILLER-CELL ACTIVITY IN POSTMENOPAUSAL WOMEN

Objective: To evaluate the impact of menopause and estradiol substitut ion on natural killer cell activity. Methods: Natural killer cell acti vity and antibody-dependent cellular cytotoxicity were measured in per ipheral blood of 53 postmenopausal and 20 premenopausal women in an in terval of 3 weeks. Postmenopausal patients were randomly assigned to r eceive either estradiol valerate (2 mg daily) orally (n = 18), estradi ol (50 mu g/24 h) transcutaneously (n = 18) or no substitution (n = 17 ), and the testing was repeated 3 weeks later. Results: Natural killer cell activity but not antibody-dependent cellular cytotoxicity was si gnificantly (P < 0.01) higher: in unsubstituted postmenopausal compare d to premenopausal subjects. Natural killer cell activity decreased bo th in orally and transcutaneously estradiol-treated patients (mean [S. D.] before vs. after 3 weeks; oral: 60.8[9.2]% vs. 52.8 [8.2]% P < 0.0 1; transcutaneous: 61.5 [10.6]% vs. 54.3 [9.1]% P < 0.01; no substitut ion: 60.6 [10.6]% vs. 59.3 [8.9]% P > 0.1), whereas antibody-dependent cellular cytotoxicity showed no changes. The addition of 0.1 to 10 ng /ml estradiol to peripheral blood mononuclear cells of untreated postm enopausal women in vitro had no influence upon natural killer cell act ivity. Conclusion: Postmenopausal women receiving no estrogen replacem ent exhibited an increased natural killer cell activity which decrease d during estrogen substitution.