Immunology of human placental trophoblast membrane antigens.

The identification of the mechanisms of immunological survival of the semiallogeneic conceptus in utero during viviparous pregnancy is central to current studies in pregnancy immunology, since any other unmatched intrauterine allograft would be expected to suffer tissue rejection. Elucidation of normal feto-maternal interactions in human uteroplacental tissues, as well as the characterization of fetal trophoblast cell surface antigen expression, has now offered insight into these processes; these have largely focussed on the lack of trophoblastic expression of classical class I MHC antigens and the specialized local immuno-regulatory response that may occur following maternal recognition of other particular trophoblast cell surface antigens. The role of trophoblastic expression of growth factor receptors, endogenous retroviral activity and cellular oncogene products in the growth and differentiation of trophoblast, and its interaction with the host maternal tissues in early pregnancy, remains to be further clarified.