CXCL8 and rheumatoid arthritis: SF concentrations of IL-8 were significantly higher in RA patients (583.6 (1,086.4) pg/ml) than in OA patients (429 (87.3) pg/ml; P < 0.05) and in the asymptomatic organ donor population (451 (170.7) pg/ml; P < 0.05).