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Human monocytes express CD163, which is upregulated by IL-10 and identical to p155
T H Sulahian1, P Högger, A E Wahner
1Department of Physiology, Dartmouth Medical School, Lebanon, NH, 03756, USA.
Abstract:
CD163 is a glucocorticoid-inducible member of the scavenger receptor cysteine-rich family of proteins. Previous reports have indicated that CD163 is highly expressed on human macrophages, but found on less than 50% of peripheral blood monocytes. We now show that >99% of all CD14 positive monocytes express CD163 and that monocyte derived dendritic cells express low levels of CD163. We also show that IL-10, like glucocorticoids, induces high CD163 expression on cultured human monocytes. Glucocorticoid induced CD163 expression was not inhibited by anti-IL-10 and was additive with IL-10 treatment, suggesting that glucocorticoids increase CD163 expression by an IL-10 independent mechanism. Other anti-inflammatory cytokines (IL-4 and IL-13) did not 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 transfected with the cDNA for CD163 were positive when probed with either mAb RM3/1 (which recognizes CD163) or Mac 2-48 (which defines p155).
Insights
CD163 is highly expressed on nearly all monocytes, unlike previously thought. Glucocorticoids and IL-10 induce CD163 expression on monocytes through independent pathways.
Area of Science:
- Immunology
- Cell Biology
Background:
- CD163, a scavenger receptor, is known to be expressed on macrophages.
- Previous studies reported low expression on peripheral blood monocytes (<50%).
Purpose of the Study:
- To clarify the expression pattern of CD163 on human monocytes and monocyte-derived cells.
- To investigate the regulatory mechanisms of CD163 expression, including the roles of glucocorticoids and IL-10.
- To determine if the monocyte marker p155 is identical to CD163.
Main Methods:
- Flow cytometry analysis of peripheral blood monocytes and monocyte-derived dendritic cells.
- Culture of human monocytes with glucocorticoids and cytokines (IL-10, IL-4, IL-13).
- Western blot and flow cytometry on HEK 293 cells transfected with CD163 cDNA, using antibodies for CD163 and p155.
Main Results:
- >99% of CD14+ monocytes express CD163; monocyte-derived dendritic cells show low expression.
- Interleukin-10 (IL-10) and glucocorticoids induce high CD163 expression on cultured monocytes.
- Glucocorticoid-induced CD163 expression is IL-10 independent and additive with IL-10.
- IL-4 and IL-13 do not increase CD163 expression.
- The monocyte/macrophage marker p155 is confirmed to be identical to CD163.
Conclusions:
- CD163 is ubiquitously expressed on human monocytes, revising previous understanding.
- Glucocorticoids and IL-10 are key inducers of monocyte CD163 expression via distinct pathways.
- The identity of p155 as CD163 provides functional context for this scavenger receptor on monocytes.