Renal F4/80CD11c mononuclear phagocytes display phenotypic and functional characteristics of macrophages in health and in Adriamycin nephropathy

Conventional markers of macrophages (MΦs) and dendritic cells (DCs) lack speci ficity and often overlap, leading to confusion and controversy regarding the precise function of these cells in kidney and other diseases. This study aimed to identify the phenotype and function of renalmononuclear phagocytes (rMPs) expressing key markers of both MΦs and DCs. F4/80CD11c cells accounted for 45% of total rMPs in normal kidneys and in those from mice with Adriamycin nephropathy (AN). Despite expression of the DC marker CD11c, these double-positive rMPs displayed the features of MΦs, including MΦ-likemorphology, high expression of CD68, CD204, and CD206, and high phagocytic ability but low antigen-presenting ability. F4/80CD11c cells were found in the cortex but not in the medulla of the kidney. In AN, F4/80CD11c cells displayed an M1 MΦ phenotype with high expression of inflammatory mediators and costimulatory factors. Adoptive transfer of F4/80CD11c cells separated from diseased kidney aggravated renal injury in AN mice. Furthermore, adoptive transfer of common progenitors revealed that kidney F4/80CD11c cells were derived predominantly from monocytes, but not from pre-DCs. In conclusion, renal F4/80CD11c cells are a major subset of rMPs and display MΦ-like phenotypic and functional characteristics in health and in AN.