The Immunology of Reproduction

Immunological principles are the same, whether they are studied or used by either a basic immunologist, a pediatrician, or an endocrinologist, surgeon or obstetrician. We simply have not yet come to understand, completely, the intricate complexity of the systems that modify and control the "immune system" itself. Growing understanding of the effects of modifications and relationships to changes in all other systems during pregnancy on the immunological systems has been fascinating, and the study of these effects is a growing area of interest. Pregnancy, similar to the tumor-host interrelationship, is characterized by the acceptance of a graft which bears antigens which are different from those of the maternal host. Studies of the role of the immune system in transplantation and tumor immunology have elucidated fundamental principles which have been used in therapy and management. There has, therefore, been an increasing awareness and curiosity in the scientific community concerning the successful maternal acceptance of the semi-allogeneic conceptus. A comprehension of the immunological mechanisms which allow the continuation of a histoincompatible allograft could possibly lead to the development of more appropriate approaches to immunotherapy of malignancies or clinical transplantation. The need to understand these mechanisms is also derived from the potential role of the immune system in the process of normal reproduction. The pathogenesis and etiology of diseases of reproduction, such as spontaneous abortion, preeclampsia, congenital abnormalities, maternal intravascular coagulation, intrauterine growth retardation, infertility, and trophoblastic tumors, to name only some of the diseases associated with pregnancy, remains unestablished. The lack of a complete understanding of the basic mechanisms involved in these deviations from the "normal" state does not imply that they are immunological in origin. However, a growing amount of data suggests that the immune system is involved. I A considerable amount of data is now available concerning mechanisms contributing to the successful acceptance of the fetus." The role of Fcv and transferrin receptors on the syncytiotrophoblast, the pattern of paternally derived antigen expression at materno-fetal interfaces, immunological factors that specifically impede maternal lymphocyte responses to paternal antigens, and the production, locally, of nonspecific immunosuppressive substances have been the subjects of several recent reviews.v" One recent study comparing the cAMP levels in lymphocytes of the same women both while they are pregnant and several months after they have delivered, suggests