Influence of complement on the chemiluminescent response of human leukocytes to immune complex

Vaccine bacteria of Francisella tularensis were mixed with human serum containing specific antibodies against the same organism, and the mixture was incubated at 37 degrees C for 30 min. The mixture induced a two-peak chemiluminescent response in polymorphonuclear leukocytes. The initial peak was induced by a soluble agent, formed during incubation. The formation of this agent involved the activation of complement component C5. The second peak of the chemiluminescent response was induced by the opsonized bacteria; this peak was augmented by complement component C3, whereas C5 had no influence.