Development of peritoneal macrophage along a dendritic cell lineage in response to uptake of oligomannose-coated liposomes

In this study, we investigate the potential of peritoneal macrophages to differentiate into dendritic cell (DCs) in response to preferential uptake of oligomannose-coated liposomes (OMLs). About 30% of peritoneal cells (PECs) preferentially took up OMLs that were administered into the peritoneal cavity. The OML-ingesting cells expressed CD11b and F4/80, but lacked CD11c expression, indicating that the OML-ingesting PECs with a CD11bhighCD11c− phenotype are resident peritoneal macrophages. During in vitro cultivation, CD11c+ cells arose among the PECs with ingested OMLs. CD11c+ cells also developed among enriched peritoneal CD11bhighCD11− cells from OML-treated mice, and the resulting CD11c+ cells expressed co-stimulatory molecules and MHC class II. In addition, OML-ingesting CD11bhighCD11c+ cells were found in spleen after the enriched peritoneal macrophages with ingested OMLs were transplanted in the peritoneal cavity of mice. These results show that a fraction of peritoneal macrophages can differentiate into mature DCs following uptake of OMLs.