Immune complex activation of neutrophils and enhancement of the activation by rheumatoid factor and complement.

The activation of human neutrophils by heat aggregated human immunoglobulin and preformed immune complexes was studied using a chemiluminescent technique. Insoluble aggregates of large size and complexes with antigen/antibody ratios at equivalence produced maximal activation. All responses were enhanced by preincubation with fresh serum. Preincubation of neutrophils with zymosan activated serum also enhanced neutrophil responses. Rheumatoid factor modulated the interaction and in excess reduced all responses, while at optimum concentration caused enhancement. These activation processes result in the release of reactive oxygen metabolites which are considered important inflammatory mediators in the pathogenesis of rheumatoid arthritis.