There is evidence that estrogen, progesterone and testosterone have modulatory effects over both cellular and humoral immune responses. These effects occur via immune-neuroendocrine interactions, involving the pituitary, gonadal steroids, thymic hormones, and the presence of specific receptors and messengers. These immune responses may be altered during pregnancy, gonadectomy, menopause and hormone therapy. Estrogen depresses the cellular immunity, suppresses the natural killer cell activity and increases the production of antibodies. Progesterone/progestogen suppresses the cellular immune system. Androgens, after metabolization in estrogens, might stimulate the humoral immune response. Hormone therapy is still broadly used in post-menopause women with the purpose of decreasing climacteric symptoms, as well as preventing genital atrophy and bone loss. Its use to attenuate the risk of cardiovascular and neurodegenerative diseases remains in debate. A few studies have been carried out to examine the effect of post-menopause hormone therapy on the immune system. There is evidence that the hypoestrogenic state, following menopause, could result in less resistance to infections. The present review examines the interaction between sexual steroids and the immune system and, based on epidemiological and clinical studies, evaluates the effects of hormone therapy on the immune responses. It was concluded that the hormone therapy normalizes the cellular immune response in post-menopausal women.
Steroids; Hormone replacement therapy; Menopause; Cytokines; Immune system