Pregnancy immunology

Abstract

Immunology is a fast developing and intriguing biomedical science, which can give rise to specific considerations about the physiological process of both successful and unsuccessful vivparous pregnancy. It is normal in clinical organ transplantation for unmatched foreign tissues (allografts) to provoke immunological rejection by the host, unless there has been prior tissue matching (histocompatibility antigen tissue typing) or immunosuppressive therapy. Thus, it is still not fully clear how, after ‘random’ mating, haplo-nonidentical fetal tissue is able to survive in the potentially hostile immunocompetent maternal environment. The majority of pregnancies survive uninterrupted and there has now been much speculation and research regarding the immunological success of pregnancy (i.e. nature’s transplant). Medawar orginally offered four nonexclusive hypotheses to explain the enigmatic immunological survival of normal pregnancy:1) the conceptus is not immunogenic and therefore does not evoke an immunological response;2) pregnancy alters the maternal immune response;3) the uterus is an immunologically privileged site;4) the placenta is an immunological barrier between the mother and the as yet immunologically incompetent fetus.Before discussing these, as well as some of the clinical immunological problems that may arise during pregnancy, it is necessary to outline some of the basic components of the normal immune system. This will lead to a description of current understanding of immunological events at the fetomaternal interface as well as the maternal immune response in human pregnancy.