CD163(Cluster of Differentiation 163) also known as HEMOGLOBIN SCAVENGER RECEPTOR, is a human protein encoded by the CD163 gene. The receptor belongs to the scavenger receptor cysteine rich family type B and consists of an 1048 amino acid residues extracellular domain, a single transmembrane segment and a cytoplasmic tail with several splice variants. CD163 is a scavenger receptorfor the hemoglobin-haptoglobincomplex. Using FISH, somatic cell hybrid analysis, and radiation hybrid analysis, Stover et al. (2000) mapped the CD163 gene to chromosome 12p13.3. Specific CD163-mediated endocytosis of haptoglobin-hemoglobin complexes was measurable in cells transfected with CD163 cDNA and in CD163-expressing myelomonocytic lymphoma cells.CD163 expression in monocytes promoted bacteria-induced proinflammatory cytokine production that could be blocked by anti-CD163 antibodies. Cells expressing human CD163 and recombinant protein containing the extracellular domain of CD163 supported adhesion of erythroblastic cells.