Mean SF levels were determined for SF EAA Glu and Asp by HPLC, and SF TNF-α, RANTES, MIP-1α and IL-8 levels were determined by immunoassay (ELISA). SF levels were obtained for the following patients during clinically active disease; rheumatoid arthritis (RA, n = 19), gout (n = 15) and osteoarthritis (OA, n = 10). *P < 0·05 when compared to RA. ^P < 0·05 when compared to gout.