The macrophage CD163 surface glycoprotein is an erythroblast adhesion receptor

Babs O Fabriek, Machteld M J Polfliet, Rianka P M Vloet, Roel C van der Schors, Antoon J M Ligtenberg, Lehn K Weaver, Christiaan Geest, Kenjiro Matsuno, Søren K Moestrup, Christien D Dijkstra, Timo K van den Berg

Research output: Contribution to journalArticleAcademicpeer-review


Erythropoiesis occurs in erythroblastic islands, where developing erythroblasts closely interact with macrophages. The adhesion molecules that govern macrophage-erythroblast contact have only been partially defined. Our previous work has implicated the rat ED2 antigen, which is highly expressed on the surface of macrophages in erythroblastic islands, in erythroblast binding. In particular, the monoclonal antibody ED2 was found to inhibit erythroblast binding to bone marrow macrophages. Here, we identify the ED2 antigen as the rat CD163 surface glycoprotein, a member of the group B scavenger receptor cysteine-rich (SRCR) family that has previously been shown to function as a receptor for hemoglobin-haptoglobin (Hb-Hp) complexes and is believed to contribute to the clearance of free hemoglobin. CD163 transfectants and recombinant protein containing the extracellular domain of CD163 supported the adhesion of erythroblastic cells. Furthermore, we identified a 13-amino acid motif (CD163p2) corresponding to a putative interaction site within the second scavenger receptor domain of CD163 that could mediate erythroblast binding. Finally, CD163p2 promoted erythroid expansion in vitro, suggesting that it enhanced erythroid proliferation and/or survival, but did not affect differentiation. These findings identify CD163 on macrophages as an adhesion receptor for erythroblasts in erythroblastic islands, and suggest a regulatory role for CD163 during erythropoiesis.

Original languageEnglish
Pages (from-to)5223-9
Number of pages7
Issue number12
Publication statusPublished - 15 Jun 2007

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