Expression of macrophage migration inhibitory factor transcript and protein by first-trimester human trophoblasts

Macrophage migration inhibitory factor (MIF) was originally identified for its capacity to inhibit the random migration of macrophages in vitro. To da te, the role of MIF as a pro-inflammatory cytokine, pituitary hormone, and counter-regulator of glucocorticoid action on the immune response is common ly recognized. Although recent studies suggest an involvement of MIF in rep roduction, no data exist on the expression of this cytokine in early human pregnancy. In this study, we evaluated the presence of MIF protein and mRNA in specimens of chorionic villi from first-trimester human placenta. Tissu es were obtained at 6-10 wk of gestation and analyzed by Western blotting, reverse transcription-polymerase chain reaction, and immunohisto-chemistry. Our results demonstrate that human villous tissue is a novel site of MIF s ynthesis. In addition, immunohistochemical analysis identified MIF protein in the cytotrophoblasts of both the inner layer of villi and in the trophob lastic cell islands. We speculate that in view of its proinflammatory featu res, MIF might play a critical role in human implantation and in early embr yonic development.