Quatification of phagocytosis by human neutrophils. The use of radiolabelled staphylococcal protein A-IgG complexes.

Human polymorphonuclear leucocytes suspended in a serum-free medium ingest radiolabelled insoluble staphylococcal protein A-IgG complexes, providing a quantitative measure of phagocytosis. The degree of uptake of protein A-IgG complexes is dependent on the cell concentration, the amount of immune precipitates and duration of incubation. The rate of phagocytosis is enhanced by the presence of serum. During the process of ingestion of immune precipitates, release of the lysosomal enzyme myeloperoxidase but not of the cytoplasmic enzyme lactic dehydrogenase occurs.