RECEPTOR EXPRESSION IN SYNOVIAL-FLUID NEUTROPHILS FROM PATIENTS WITH RHEUMATOID-ARTHRITIS

Objectives-The aim of this study was to determine if neutrophils isola ted from the blood and synovial fluid of patients with rheumatoid arth ritis had patterns of receptor expression resembling those of blood ne utrophils from controls which had been activated and primed in vitro. Methods-Fluorescence activated cell sorting was used to measure recept or expression in paired blood and synovial fluid neutrophils from pati ents and in control neutrophils exposed to phorbol myristate acetate a nd granulocyte-macrophage colony stimulating factor. Results-There was no significant difference in the patterns of receptor expression in b lood neutrophils from patients and healthy controls, but neutrophils i n the synovial fluid had been primed and activated within the joint. A bout 50% of rheumatoid synovial fluid neutrophil samples expressed Fcg amma RI, a high affinity receptor for monomeric IgG, which is only exp ressed in neutrophils exposed to cytokines. Conclusions-Synovial fluid neutrophils are activated and primed within the inflamed joint and he nce their ability to respond to activating factors such as immune comp lexes will be modulated. As the expression of Fcgamma RI requires acti ve biosynthesis, this work indicates that selective gene activation oc curs when neutrophils are recruited into rheumatoid joints.