INCREASED EXPRESSION OF C1Q RECEPTORS ON NEUTROPHILS FROM INFLAMMATORY JOINT FLUIDS

Clq receptor (C1qR) expression was determined by immunofluorescence fl ow cytometry on neutrophils from paired peripheral blood and synovial fluid samples from 21 patients with rheumatoid arthritis (RA) and 13 p atients with other articular diseases (OAD). In both patient groups th e levels of C1qR on circulating neutrophils were similar to that obser ved for normal control subjects, whereas on synovial fluid neutrophils significantly higher levels of receptor expression were observed. The mean percentage increases observed were: RA patients 47%, OAD patient s 72%. Clq-bearing immune complexes were most prevalent in patients wi th RA, with the highest concentrations being found in synovial fluid s amples. No correlation between immune complex levels and neutrophil C1 qR expression was noted. Upregulation of C1qR expression is a feature of activated neutrophils from inflammatory joint fluids.