[Immunologic tolerance of fetal allograft].

In mammals, reproduction involves two potentially incompatible mechanisms: viviparity and development of a competent immune system. Thus the maternal and foetal organisms must respond by developing immunologic tolerance. The phenomenon does not involve total immunosuppression, but includes several highly precise processes initiated at conception. It is known that cell- and humour-mediated processes occur but their relative importance remains to be elucidated. Cytokines, especially those mediating T-helper2 cell response appear to play a predominant role in inducing immunologic tolerance to the foetal allograft. A better understanding of these mechanisms could have major implications in the diagnosis and treatment of repeated miscarriage and unexplained infertility.