[Specific immune relationships among the mother, the fetus and the trophoblast. Present-day aspects].

Studying the literature, which is becoming larger and larger, the authors note that there is increasing understanding about the immune response that allows a harmonious development of the feto-placental unit. After the recognition of certain trophoblastic antigens there followed the activation of lymphocytes which synthesize substances favourable to trophoblastic growth. At the same time protective mechanisms which inhibit the generation and activation of immunological factors which are normally found when allografts are rejected, were recognized. Also recognized were other systems able to suppress aggressive features that can become active during pregnancy.