Active lifestyle offsets HRT-induced suppression of T cell reactivity to mitogens

Objective. The purpose of the study was to investigate the combined impact of hormone replacement therapy (HRT) and active lifestyle on the phenotypic profile and in vitro activities of specific immune cells in postmenopausal women. Methods. Healthy postmenopausal women aged 45-70 were assigned to one of four groups: (a) HRT/sedentary (n = 9); (b) HRT/active (n = 12); (c) no HRT/sedentary (n = 10); and (d) no HRT/active (n = 9). Blood samples were collected from each subject on 3 days within 1 week. The mean value of three samples was used to assess the in vitro response of T lymphocytes to the mitogens phytohemagglutinin and concanavalin A and natural killer cell activity. One of three blood samples was utilized for phenotypic analysis of circulating leukocytes. Results. The mitogenic reactivity of T lymphocytes in whole blood cultures for the groups receiving HRT was lower than from the groups not receiving HRT. There also was a trend for T lymphocyte reactivity to be higher in the active women when compared to the sedentary women. In contrast, the phenotypic profile of leukocytes and natural killer cell activity were not significantly different for samples collected from the four groups. Conclusions. These data suggest that the suppressive effect of HRT on T cell function in postmenopausal women may be attenuated by a physically active lifestyle. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.