The presence of functional mannose receptor at the materno-fetal interface

INTRODUCTION: The mannose receptor (MR) is endocytic receptor and recognize glycoproteins including those produced during inflammation and tissue remodeling. The aim was to analyze distribution, regulation, endocytic activity and possible natural ligand for the MR at the materno-fetal interface characterized by extensive tissue remodeling. MATERIAL AND METHODS: The MR+ cells were analyzed by immunohistology in early pregnancy decidua and term placenta. Early decidual mononuclear cells (DMC), obtained by enzymatic digestion were used freshly, untreated or pretreated by mannan, PAM-1 anti-MR antibody or Tumor Associated Glycoprotein-72 (TAG-72) or cultured 18 hrs with progesterone, Progesterone Induced Blocking Factor (PIBF), IL-4 or in the medium only. The MR expression and FITC-Dextran uptake were analyzed by flow cytometry or immunocytochemistry. RESULTS: Contrary to dispersed distribution in term placenta, the MR+ cells surrounded glands in early pregnancy decidua. The MR was present on 14% of DMC and distributed mostly on CD14+ cells. The expression of the MR on CD14+ cells decreased following 18 hr culture and was accompanied by the reduction of FITC-Dextran uptake. Progesterone and IL-4 prevent decrease of the MR on CD14+ cells, but PIBF was inefficient. PAM-1 anti-MR antibody, mannan and TAG-72 reduced FITC-Dextran uptake by decidual macrophages. CONCLUSIONS: Macrophages surrounding the glands predominate within MR+ population in early pregnancy decidua and can bind the ligands for carbohydrate recognition domain of the MR in a correlation with the expression of the receptor. TAG-72, secretory phase glycoprotein could be a natural ligand for the MR on early decidual macrophages.