Female sex hormones and the immune system.

Generally, females have a more active immune response and a concomitantly higher incidence of autoimmune diseases as compared to males. Growing evidence has shown that female sex hormones play a major role in this heightened immune response. However, despite extensive studies, the mechanisms of female sex hormones are not precisely understood. Earlier evidence suggest that female sex hormones acted via the thymus gland. In recent years it has become apparent that female sex hormones have distinct effects on the function of T cells, B cells, or mononuclear phagocytes. The presence of sex hormone receptors on the immune cells indicates the effects of female sex hormones on these cells are mediated by these receptors. The effects of female sex hormones on the immune system and the possible mechanisms are discussed in this review. Female sex hormone modulation of immune responses provides a basis for understanding gender-related differences in certain autoimmune and neoplastic disorders.