Is the trophoblast an immune regulator? The role of Toll-like receptors during pregnancy.

In the early 1950s, Medawar recognized for the first time the unique immunology of the maternal/ fetal interface and its potential relevance for transplantation. In his original work, he described the fetal allograft analogy whereby the fetus may be viewed as a semi-allogeneic conceptus that has evaded rejection by the maternal immune system. Although numerous hypotheses have been proposed to prove this observation, none have demonstrated that the maternal immune system is antagonist to the invading trophoblast. In the present article, we have reviewed recent studies demonstrating the expression and function of Toll-like receptors (TLRs) in trophoblast cells, and, based on these data, we propose an alternative view for maternal/fetal immune interactions.