Depressed exocytosis by rheumatoid neutrophils in vitro

Polymorphonuclear leucocytes and monocytes have been isolated from the peripheral blood of patients with rheumatoid arthritis and healthy controls using Percoll gradient centrifugation. These cells have been tested for their ability to release superoxide anion and to undergo exocytosis following stimulation with heat-aggregated IgG. Monocytes from patients and controls react similarly in these assays but neutrophils from the patients release less beta-glucuronidase than do normal cells. This could not be related either to the expression of cell surface Fc receptors or to oxidative metabolism and does not appear to be an effect of the administration of non-steroidal anti-inflammatory drug therapy. It is suggested that rheumatoid neutrophils are not inherently defective but are less responsive to activation in vitro because of prior exposure to immune complexes in vivo.