Effect of C2-Deficiency on the Bactericidal Activity and Chemiluminescence Responses of Human Neutrophils in vitro

Abstract

of invading bacbria by neutrophilic polymorphonuclear leukocytes (PMN) is an important aspect of pulmonary host defense.l Opsonins play a key role in the process by facilitating uptake of bacteria by PMN. Opsonic substances m serum include heat-stable components such as specific antibody, which usually develops later in the course of infection, and heat-labile factors, like those produced rapidly by activation of the complement cascade.¶ Fdlowing engulfment of opsonized bacteria, PMN consume oxygen, undergo a series of metabolic reactions, and produce highly reactive oxygen intermediates.a.4 These oxygen byproducts are necessary for optimal killing of ingested bacteria by PMN.' In association with production of these oxygen intermediates, PMN generate chemiluminescence. This light can be measured in a scintillation counter and used to accurately quantitate the metabolic reactions of PMN to engulfment of bacte~ia.&-~ The nature of the requirements for the complex processes by which PMN pick up and kill bacteria and produce chemiluminescence remain poorly d&d8*@ In the present investigation, we evaluated the effect of a selective absence of the second component of camplement (C2) on the uptake of bacteria by PMN, using both a standard assay of PMN bactericidal activity and an assay of the quantitative chemiluminemmce response of PMN stimulated by bacteria.@*7J0 The patient we studied had a complete selective absence of C2 by radial immun- or immundectrophoresis analy