Stimulation of phagocytosis by human lysozyme

Human lysozyme in physiologic concentrations (10--400 mug/ml) significantly (p less than 0.001) stimulates the phagocytosis of yeast cells by human polymorphonuclear leukocytes. This stimulating effect was observed even in the absence of serum factors. Hen egg white lysozyme or protamine sulfate had no effect on phagocytosis. The stimulating effect of human lysozyme was not the result of opsonization but was apparently related to the effects on constituent membranes of the phagocytic cells.