CD163 is a member of the Group B scavenger receptor cysteine-rich (SRCR) superfamily. It is also known as GHI/61, M130, RM3/1, p155, the hemoglobin-haptoglobin complex receptor, or macrophage-associated antigen.It is a glycoprotein with an apparent molecular weight of 134 kDa under non-reducing conditions and 155 kDa under reducing conditions. CD163 is predominantly expressed on macrophages, Kupffer cells, monocytes, subsets of dendritic cells, and subsets of hematopoietic stem/progenitor cells.CD163 binds the haptoglobin-hemoglobin (Hp-Hb) complex and TNF-like weak inducer of apoptosis (TWEAK). It serves as the receptor for hemoglobin scavenging and modulates cytokine production by macrophages.Membrane-bound CD163 can be proteolytically cleaved by metalloproteinases (e.g., ADAM17, MMPs), releasing its soluble form (sCD163). Elevated serum levels of sCD163 have been strongly associated with numerous inflammatory diseases.
