Effects of Hormone Therapy on the Immune Systems of Postmenopausal Women With Chronic Infections

Hardening of the arteries (atherosclerosis) and heart disease are much more common in men than in women. However, as women grow older, especially after menopause the incidence of atherosclerosis and heart disease increases. These findings suggest that estrogen may be protective and help in preventing heart disease. Studies of large groups of post-menopausal women suggest that hormone replacement therapy (therapy that includes estrogen) reduces the risk of heart disease. Estrogen causes favorable changes in particles that carry cholesterol in the blood stream and improves function of blood vessels. Estrogen may also stimulate the immune system's ability to fight off infections that may lead to or contribute to atherosclerosis. Researchers believe two specific infectious agents (Chlamydia pneumoniae and human cytomegalovirus) may cause damage to the lining of blood vessels resulting in inflammation and the development of atherosclerosis. The purpose of this study is to determine if estrogen treatment can change how the immune system responds to chronic infections, by Chlamydia pneumoniae and human cytomegalovirus, in postmenopausal women.