Increased excretion of two sialic acid-containing trisaccharides in the urine of patients with rheumatoid arthritis.

The urinary excretion of sialic acid-containing trisaccharides in patients with active rheumatoid arthritis was studied. Sialyl-lactose and sialyl-N-acetyllactosamine were identified and their excretion patterns studied by thin layer and gas chromatography. The urinary output of sialyl-lactose was greater in patients with active rheumatoid arthritis (48.2 +/- 6.1 mg/24 h, SEM, n = 6) than in healthy subjects (19.8 +/- 3.7 mg/24 h, SEM, n = 5; P less than 0.01). The excretion of sialyl-N-acetyllactosamine was also higher in the rheumatoid group (18.5 +/- 2.1 mg/24 h, SEM, n = 6) than in the controls (11.1 +/- 1.2 mg/24 h, SEM, n = 5; P less than 0.05). The qualitative excretion patterns of the sialyl-oligosaccharide fraction were similar for the two groups as judged from the thin layer chromatograms. Correlating the results with the clinical state of the patients with rheumatoid arthritis suggests that the urinary level of the sialyl-oligosaccharides reflects the activity of the disease. A proposed mechanism for the increased excretion of sialic acid-containing trisaccharides in rheumatoid arthritis is presented.