DHRS9 is a Stable Marker of Human Regulatory Macrophages.

Background: The human regulatory macrophage (Mreg) has emerged as a promising cell type for use as a cell-based adjunct immunosuppressive therapy in solid organ transplant recipients. In this brief report, dehydrogenase/reductase 9 (DHRS9) is identified as a robust marker of human Mregs. Materials and Methods: The cognate antigen of a mouse monoclonal antibody raised against human Mregs was identified as DHRS9 by immunoprecipitation and MALDI-MS sequencing. Expression of DHRS9 within a panel of monocyte-derived macrophages was investigated by quantitative PCR, immunoblotting and flow cytometry. Results: DHRS9 expression discriminated human Mregs from a panel of in vitro derived macrophages in other polarisation states. Likewise, DHRS9 expression distinguished Mregs from a variety of human monocyte-derived tolerogenic antigen-presenting cells in current development as cell-based immunotherapies, including Tol-DC, Rapa-DC, DC-10 and PGE2-induced MDSC. A subpopulation of DHRS9-expressing human splenic macrophages was identified by immunohistochemistry. Expression of DHRS9 was acquired gradually during in vitro development of human Mregs from CD14+ monocytes and was further enhanced by IFN-[gamma] treatment on day 6 of culture. Stimulating Mregs with 100 ng/ml lipopolysaccharide for 24-hours did not extinguish DHRS9 expression. Dhrs9 was not an informative marker of mouse Mregs. Conclusion: DHRS9 is a specific and stable marker of human Mregs. This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. Copyright (C) 2017 Wolters Kluwer Health, Inc. All rights reserved.

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