Human monocytes express CD163, which is upregulated by IL-10 and identicalto p155

CD163 is a glucocorticoid-inducible member of the scavenger receptor cystei ne-rich family of proteins. Previous reports have indicated that CD163 is h ighly expressed on human macrophages, but found on less than 50% of periphe ral blood monocytes. We now show that >99% of all CD14 positive monocytes e xpress CD163 and that monocyte derived dendritic cells express low levels o f CD163. We also show that IL-10, like glucocorticoids, induces high CD163 expression on cultured human monocytes. Glucocorticoid induced CD163 expres sion was not inhibited by anti-IL-10 and was additive with IL-10 treatment, suggesting that glucocorticoids increase CD163 expression by an IL-10 inde pendent mechanism. Other anti-inflammatory cytokines (IL-4 and IL-13) did n ot increase CD163 expression. in addition, we show that p155 (a previously identified monocyte/macrophage marker of unknown function) shares identity with CD163. Western blots and flow cytometric analysis of HEK 293 cells tra nsfected with the cDNA for CD163 were positive when probed with either mAb RM3/1 (which recognizes CD163) or Mac 2-48 (which defines p155). (C) 2000 A cademic Press.