Circulating hyaluronate in rheumatoid arthritis: relationship to inflammatory activity and the effect of corticosteroid therapy.

The mean serum hyaluronate concentration in a group of patients with rheumatoid arthritis (n = 37) was 232 +/- 182 (SD) microgram/l and significantly greater (p less than 0.001) than that of age and sex matched healthy controls (mean level 42 +/- 25 micrograms/l) as well as that of patients with ankylosing spondylitis (mean level 58 +/- 33 micrograms/l). In rheumatoid arthritis positive correlations were found between serum hyaluronate and acute-phase plasma proteins, while neither rheumatoid factor titre nor the presence of circulating immune complexes were related to the hyaluronate levels. Increased serum hyaluronate could not be explained by impaired renal or liver function or by drug therapy. During treatment with corticosteroids but not with non-steroidal anti-inflammatory drugs the serum hyaluronate concentrations were significantly reduced. The data obtained suggested an increased production of hyaluronate in rheumatoid arthritis, and the increase seems to be related to the activity of the inflammatory process.