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B cell subsets in postmenopausal women and the effect of hormone replacement therapy
M Kamada1, M Irahara, M Maegawa
1Department of Obstetrics and Gynecology, School of Medicine, The University of Tokushima, 3-18-15 Kuramoto-cho, 770-8503, Tokushima, Japan. kamada@clin.med.tokushima-u.ac.uk
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)-1alpha were measured by immunofluorescence and by radioimmunoassay, respectively. Thirteen women were examined prospectively before and during HRT.
Results:
In late postmenopausal women (> or = 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.