Immunologic Changes During Pregnancy

Attempts to understand why the fetus is not rejected by the mother have led us to an ongoing and fascinating understanding of both innate and adaptive immune mechanisms of maternal recognition during pregnancy. As gestation evolves, the developing embryo becomes isolated within a semi-permeable environment. The anatomic organization of the maternal-fetal interface, absence of classical MHC molecules on the trophoblast surface, uterine NK cells, the cytokine milieu, macrophages, T and B cell populations, antibody production, indoleamine 2,3-deoxygenase, complement regulatory proteins, and sex hormones allow for the integrity of the maternal-fetal interface and provide an example of cellular recognition. As immunologic changes develop, the balance required for host defense and control of autoimmunity is transformed and the pregnant female becomes susceptible to infections and changes in disease activity. This chapter provides an overview of the fundamental immunologic principles that determine the immunobiology of pregnancy by focusing on some of the cellular and molecular interactions known to be involved in immune function during gestation. How such changes influence the clinical manifestations of autoimmune diseases in the pregnant female and affect susceptibility to infection is discussed briefly.