Evaluation of serum opsonic capacity by quantitating the initial chemiluminescent response from phagocytizing polymorphonuclear leukocytes.

Phagocytically activated polymorphonuclear leukocytes produced a chemiluminescence that could be correlated metabolically with the stimulated oxidation of glucose via the hexose monophosphate shunt, The chemiluminescence observed was considered to originate from the relaxation of electronically excited carbonyl groups produced during singlet molecular oxygen-mediated microbicidal oxidation of the ingested microbe. With adequate adjustment of leukocyte and bacterial concentrations, the rate of chemiluminescence increase was nearly constant for the first minutes after initiation of phagocytosis. This rate was dependent on the quantity of bacteria phagocytized by the leukocytes. If both leukocytes and bacterial concentrations were held constant, this initial rate of chemiluminescence reflected the opsonic capacity of the sera used for opsonization. The prior absorption of opsonins from serum resulted in a decresed rate of chemiluminescence related to the quantity of bacteria used for absorption. Heating of sera to 56 degrees C for 30 min resulted in a great decrease in the chemiluminescent responses and may reflect the role of complement in the opsonization process.