Immunoglobulin G (IgG), complement (C3b) and fibronectin (FN) in plasma enhanced the phagocytosis of anionic and hydrophobic particles by granulocytes. Fibrinogen in plasma suppressed the phagocytosis cationic and hydrophobic particles. The phagocytosis of hydrophilic carboxylated particles with highly negative charges were enhanced by C3b in plasma. Granulocytes recognized the particles through their membrane receptors (Fc, C3b and FN). The degree of phagocytosis in plasma was attributed to the protein absorption from plasma on particles, and the adsorption behaviors such as species, amounts, orientation, and conformational change of proteins were depended on their surface properties of particles. The morphology of the granulocytes varied according to the size of particles. The particles with a diameter less than 7μm were able to be phagocytosed by granulocytes, and 10-20μm particles were covered with many spreading granulocytes. Intracellular microfilament and microtubule and metabolic energy played an important roles in phagocytosis of particles by granulocytes, judging from the results using various inhibitors.
