Interaction of circulating immune complexes with granulocyte function in patients with rheumatoid arthritis.

The sera and peripheral blood granulocytes of 10 patients with rheumatoid arthritis and of 10 healthy controls were investigated for the presence of soluble immune complexes and for cellular dysfunction. Using the Rajicell-radioimmunoassay, immune complexes were detected in 7 out of 10 rheumatoid sera. In one patient the presence of immune complexes was demonstrated by immunofluorescence. In all rheumatoid patients with circulating immune complexes decreased chemotactic reactivity and diminished bactericidal capacity of the neutrophils were observed. Incubation of rheumatoid granulocytes with pooled AB-serum or pretreatment of neutrophils of healthy controls with immune complexes containing rheumatoid sera resulted in a reduced number of comparable cellular dysfunctions including increased release of lysosomal enzymes, strongly correlated with the presence of intracellular phagocytosed immune complexes. Phagocytosis and increase of oxidative cell metabolism during phagocytosis were not influenced by circulating immune complexes. Based on our in vitro findings we suggest that the described immune complex-dependent granulocyte dysfunctions are possible responsible for the high risk of local or systemic bacterial diseases in patients with rheumatoid arthritis.