CD163 is a transmembrane protein which belongs to the scavenger receptor cysteine-rich(SRCR) superfamily. This protein is a scavenger receptor for the hemoglobin-haptoglobin complex and is a marker for monocytes and macrophages. Soluble CD163(sCD163), as a result of ectodomain shedding during inflammatory activation of macrophages, circulates in blood and has been suggested as a plasma/serum marker for macrophage activity.