CD163 is a protein encoded by the CD163 gene in humans. It belongs to the scavenger receptor cysteine-rich type B family and contains an extracellular domain composed of 1048 amino acid residues, a single transmembrane segment, and a cytoplasmic tail with several splice variants. It is a scavenger receptor for the haptoglobin-hemoglobin complex and serves as a marker for the monocyte/macrophage lineage. The soluble form of this receptor, known as sCD163, is present in the plasma. sCD163 is generated by shedding of the extracellular domain of the membrane-bound receptor and is upregulated in a wide range of inflammatory diseases, including liver cirrhosis, type 2 diabetes, macrophage activation syndrome, Gaucher’s disease, sepsis, HIV infection, rheumatoid arthritis, and Hodgkin’s lymphoma.