The presence of functional mannose receptor on macrophages at the maternal-fetal interface

Background: The mannose receptor (MR) is involved in the initiation of the immune response and regulation of homeostasis during inflammation and tissue remodeling. Methods: Distribution, endocytosis and possible natural ligand tumor associated glycoprotein-72 (TAG-72) for the MR have been examined by immunohistology, immunocytochemistry and flow cytometry at the maternal-fetal interface, characterized by extensive tissue remodeling. Results: Contrary to disseminated distribution of the MR positive (MR+) cells in term placenta, the MR+ cells of early pregnancy decidua intimately surrounded glands and followed tissue distribution of CD14 positive cells. The mannose receptor was present on freshly isolated first trimester decidual mononuclear cells and distributed mostly on macrophages (77.08 ± 10.55%, mean ± SD). The expression of the MR on CD14 positive cells decreased following 18 h culture (P <0.01) and was accompanied by the reduction of fluorescein isothiocyanate (FITC)-dextran uptake. PAM-1 anti-MR antibody, mannan and TAG-72 reduced FITC-dextran uptake by decidual macrophages. Conclusions: These data indicate that the MR+ macrophages, surrounding early decidual glands, are able to internalize ligands for carbohydrate recognition domain of the receptor, including decidual secretory phase mucin TAG-72.