[Immunological aspect of pregnancy].

Pregnancy is a temporary semi-allograft that survives for nine months. The importance of this event for the survival of the species justifies several tolerance mechanisms that are put into place at the beginning of pregnancy, some of which occur even at the time of implantation. The presence of multiple tolerance mechanisms and the richness of the means employed underline the central importance of the trophoblast. Understanding these mechanisms, and in particular, their integration into an overall scheme, enables the anomalies encountered in certain pathologies of pregnancy to be placed into context. Understanding these mechanisms and their interruption at the end of pregnancy should improve our understanding of disappointing results from current immunological treatments facilitate the implementation of new prophylactic and therapeutic strategies.