CD163, alternatively termed scavenger receptor cysteine-rich type 1 protein M130,1 represents a signal-transducing transmembrane protein whose expression is sharply increased during acute inflammation,2 and it is uniquely expressed on cells originating from the monocyte lineage.  A key function of CD163 is to mediate the elimination of hemoglobin/haptoglobin complexes through macrophage uptake and internalization. 2 Consequently, CD163 is instrumental in promoting the anti-inflammatory response and in shielding tissues against oxidative damage and inflammation induced by hemoglobin. 3 Anti-CD163 antibodies identify cells belonging to the monocytic-macrophage lineage, with observed expression in bone marrow3 as well as in histiocytic tumors.