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

Objectives: In elderly subjects the capacity for antibody production is dep ressed. This immunosenescence state of humoral immunity is associated with the occurrence of autoimmune disorders involving CD5(+) B (B-1) cells. Sinc e 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 wome n during the postmenopausal period was determined. The effect of hormone re placement therapy (HRT) on B cell subsets was examined to establish whether the administration of gonadal hormones influence humoral immunity in postm enopausal women. Methods: Forty six untreated pre- and postmenopausal women and 39 women on HRT were studied. The proportion of B-1 (CD5(+)) and conve ntional CD5(-) B (B-2) lymphocytes was determined by two-color flow cytomet ry. Serum autoantibodies to a nuclear antigen and to interleukin (IL)-1 alp ha were measured by immunofluorescence and by radioimmunoassay, respectivel y. Thirteen women were examined prospectively before and during HRT. Result s: In late postmenopausal women (greater than or equal to 30 years postmeno pausal period). the proportion of B-2 cells was significantly reduced (p < 0.01) compared to those of premenopausal and perimenopausal women. HRT indu ced 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 prod uction. Conclusion: HRT may retard the progress of immunosenescence by incr easing the production of B-2 cells. Moreover. HRT appears not to increase t he risk of autoimmune diseases developing in postmenopausal women. (C) 2001 Elsevier Science ireland Ltd. All rights reserved.