Lymphocytes, the cells responsible for making antibodies, are made in large numbers throughout life within bone marrow. A variety of evidence suggests that this process is regulated in a negative way by hormones, including estrogen. When estrogen levels are high, as they are during pregnancy, lymphocyte production is severely depressed in the mothers bone marrow. It has been a mystery why the high estrogen concentrations do not also prevent development of the babys immune system.
Dr. Hidyea Igarashi and his colleagues at OMRF may have solved this paradox. Estrogen controls lymphocyte formation, and thus replenishment of the immune system by binding to hormone receptors found only in rare precursors within adult bone marrow. Igarashi found that the receptors were not expressed on corresponding cells of the fetus. Indeed, the receptors are expressed after birth in experimental animals and man. By lacking these receptors, the immune system of the fetus is protected from estrogen and related compounds that might be present in the environment. It adds to information that various kinds of stem cells may not be the same in fetal and adult life.
Paul W. Kincade, Ph.D., the head of the research team, will present detailed findings of this research, Sex Steroids Regulate Lymphocyte Development in Adults, but not Fetal Life and Can Be Used to Resolve Early Blood Cell Precursors," at the upcoming conference, Genomes and Hormones: An Integrative Approach to Gender Differences in Physiology. The conference is being sponsored by the A
Contact: Donna Krupa
American Physiological Society