B cell subsets in postmenopausal women and the effect of hormone replacement therapy

Objectives: In elderly subjects the capacity for antibody production is depressed. This immunosenescence state of humoral immunity is associated with the occurrence of autoimmune disorders involving CD5(+) B (B-1) cells. Since estrogen is capable of stimulating the production of autoantibodies. this sex steroid hormone may be a contributing cause of the higher incidence of autoimmune diseases in women. In the present study. B cell subsets in women during the postmenopausal period was determined. The effect of hormone replacement therapy (HRT) on B cell subsets was examined to establish whether the administration of gonadal hormones influence humoral immunity in postmenopausal women. Methods: Forty six untreated pre- and postmenopausal women and 39 women on HRT were studied. The proportion of B-1 (CD5(+)) and conventional CD5(-) B (B-2) lymphocytes was determined by two-color flow cytometry. Serum autoantibodies to a nuclear antigen and to interleukin (IL)-1 alpha were measured by immunofluorescence and by radioimmunoassay, respectively. Thirteen women were examined prospectively before and during HRT. Results: In late postmenopausal women (greater than or equal to 30 years postmenopausal period). the proportion of B-2 cells was significantly reduced (p < 0.01) compared to those of premenopausal and perimenopausal women. HRT induced a significant (p < 0.01) increase in the percentage of B-2 cells, while that of B-1 cells remained unchanged. HRT did not affect autoantibody production. Conclusion: HRT may retard the progress of immunosenescence by increasing the production of B-2 cells. Moreover. HRT appears not to increase the risk of autoimmune diseases developing in postmenopausal women. (C) 2001 Elsevier Science ireland Ltd. All rights reserved.