Two Distinct Subsets Are Identified from the Peritoneal Myeloid Mononuclear Cells Expressing both CD11c and CD115

Abstract

To this date, the criteria to distinguishperitonealmacrophages and dendriticcells(DCs) are not clear. Here we delineate thesubsetsofmyeloidmononuclearcellsin the mouseperitonealcavity. Considering phenotypical, functional, and ontogenic features,peritonealmyeloidmononuclearcellsare divided into 5subsets: largeperitonealmacrophages (LPMs), smallperitonealmacrophages (SPMs), DCs, and 2 MHCII+CD11c+CD115+subpopulations (i.e., MHCII+CD11c+CD115+CD14-CD206-and MHCII+CD11c+CD115+CD14+CD206+). Among them, 2subsetsof competent Ag presentingcellsare demonstrated withdistinctfunctional characteristics, one being DCs and the other being MHCII+CD11c+CD115+CD14-CD206-cells. DCs are able to promote fully activated Tcellsand superior in expanding cytokine producing inflammatory Tcells, whereas MHCII+CD11c+CD115+CD14-CD206-cellsgenerate partially activated Tcellsand possess a greater ability to induce Treg under TGF-β and retinoic acid conditions. While the development of DCs and MHCII+CD11c+CD115+CD14-CD206-cellsare responsive to the treatment of FLT3 ligand and GM-CSF, the number of LPMs, SPMs, and MHCII+CD11c+CD115+CD14+CD206+cellsare only influenced by the injection of GM-CSF. In addition, the analysis of gene expression profiles among MHCII+peritonealmyeloidmononuclearcellsreveals that MHCII+CD11c+CD115+CD14+CD206+cellsshare high similarity with SPMs, whereas MHCII+CD11c+CD115+CD14-CD206-cellsare related toperitonealDC2s. Collectively, our study identifies 2distinctsubpopulations of MHCII+CD11c+CD115+cells, 1) MHCII+CD11c+CD115+CD14-CD206-cellsclosely related toperitonealDC2s and 2) MHCII+CD11c+CD115+CD14+CD206+cellsto SPMs.