Activation of inflammatory cells by immune complexes containing IgE in serum and synovial fluid of patients with rheumatoid arthritis: a study using flow cytometric analysis.

Neutrophil and monocyte activation by immune complexes containing IgE from serum and synovial fluid of patients with rheumatoid arthritis is reported. Activation of the inflammatory cells was measured by stimulation of the respiratory burst with production of intracellular hydrogen peroxide. Generation of hydrogen peroxide was analysed by a flow cytometric method, using the fluorochrome dichlorofluorescein. The technique was modified to allow measurement of cell activation of both neutrophils and monocytes by immune complexes in suspension. Ten of 14 polyethylene glycol precipitates from serum of patients with rheumatoid arthritis and 10/16 synovial fluids of these patients could activate neutrophils. A positive relation was found between the activation of neutrophils and the total concentration of immune complexes, the presence of IgG, and the presence of IgE in the immune complexes. Activation of monocytes was also shown, but to a lesser extent (8/14 rheumatoid serum samples and 8/16 rheumatoid synovial fluids activated monocytes). There was a weak correlation between the concentration of IgE immune complexes and the intensity of fluorescence measured in the monocytes.