Kinetics of staphylococcal opsonization, attachment, ingestion and killing by human polymorphonuclear leukocytes: A quantitative assay using [ 3H] thymidine labeled bacteria

A method has been developed for studying quantitatively the separate processes of bacterial opsonization, phagocytosis, and killing by human polymorphonuclear leukocytes using [ 3H]thymidine labeled Staphylococcus aureus. Phagocytosis is determined by assaying for leukocytes-associated radioactivity after differential centrifugation and washing the leukocytes. Opsonization is studied by incubating bacteria with an opsonic source for varying durations and then adding leukocytes. By treatment of samples with the muralytic enzyme, lysostaphin, the attachment and ingestion phases of phagocytosis can be separated. Sampling for colony forming units after disruption of the leukocytes permits the measurement of bacterial killing. Using this method, differences in the kinetics of staphylococcal opsonization by normal and C2 deficient sera were defined, opsonic influences on the attachment and ingestion phases of phagocytosis were delineated, and the influences of different opsonins and leukocyte populations on killing were determined.