Receptor CD163 of monocytes / macrophages bound hemoglobin and its complexes with haptoglobin ( Hp - Hb ) , the receptor activates a receptor group " scavenger " for hemoglobin ( HbSR ) . Through the uptake and internalization of hemoglobin iron removal occurs as a factor inducing free radical reactions and as a factor increasing the growth and pathogenicity of bacteria. SCD163/HbSR soluble receptor is cleaved from the surface of monocytes by molecular patterns associated with pathogens at the same time , which is likely to hemolysis and the formation of Hb - Hp complexes .