The glycosaminoglycan, hyaluronan, can be detected in human synovial fluid by capillary electrophoresis (CE). Variations in peak shape make this technique unsuitable for quantitative analysis of hyaluronan in raw synovial fluid. Quantitative analysis was achieved by hydrolysis of the polymeric hyaluronan to the tetrasaccharide by the action of testicular hyaluronidase and separation of the product using CE. A UV detector operating at 200 nm was used. The X-ray contrast material, omnipaque, a propriety aqueous solution of iohexol was used as internal standard. A second peak in the electropherogram of synovial fluid was quantified. The variation in concentrations of these two components correlate with the arthritic disease state of a joint.

1. A 1H-n.m.r. method was used to measure concentrations of valine, alanine, lactate, acetate, hyaluronan and lipids in synovial fluid obtained, during the normal course of examination from the knee joints of patients attending rheumatology and orthopaedic clinics. Fluid was available from 16 patients with osteoarthritis, 18 patients with rheumatoid arthritis, four patients with meniscal tear and one patient each with systemic lupus erythematosis, mono-arthritis, synovitis and loose bodies. Four normal specimens were obtained for comparison. 2. Valine, alanine and acetate levels all showed a normal Gaussian distribution, reflecting the distributions within the serum of the sample population. 3. Lactate concentrations divided into two distinct patterns. At concentrations below 2.5 mmol/l the lactate levels showed a Gaussian distribution, reflecting the distribution in normal serum. The normal synovial fluid specimens belong to this distribution. Above 2.5-3.0 mmol/l, lactate levels were asymmetric in distribution with a long tail at higher concentrations. These high levels of lactate can be explained by the generation of lactate through anaerobic metabolism within the synovial cavity. This metabolic process is triggered by a general inflammatory condition such as in rheumatoid arthritis. 4. The distribution of n.m.r.-observable lipid concentrations in rheumatoid arthritis and osteoarthritis each shows a normal distribution and the mean concentration is significantly higher in rheumatoid arthritis. 5. An increased n.m.r.-observable hyaluronan concentration is associated with an inflammatory situation. 6. It is concluded that raised levels of lactate and n.m.r.-observable hyaluronan and lipids are useful markers to aid the clinical distinction between rheumatoid arthritis and osteoarthritis.(ABSTRACT TRUNCATED AT 250 WORDS)

Substantial and characteristic changes in composition are found between normal human synovial fluid and fluid from clinically well-defined cases of osteoarthritis and rheumatoid arthritis. The peak due to uric acid is a useful marker for the region of the electropherogram where these changes occur.

Summary:In this study, the levels of the cysteine proteinase -cathepsin B were measured in diseased synovial fluids using a steady state fluorometric assay. Cathepsin B-like activity was shown to be present in all the samples analysed, with the rheumatoid arthritic synovial fluids possessing significantly higher concentrations (mean value ca. 416 mg/1) than the osteoarthritic fluids (mean value ca. 142.4 mg/1). In addition, upon treatment with pepsin, all of the rheumatoid arthritis samples were shown to possess additional cathepsin B-like activity, suggesting the presence of a reservoir of latent precursor molecules. By utilising a recently developed biotinylated affmity label for cathepsin B-like proteinases and sheep anti-(human cathepsin B) antibodies, used in combination with SDS-PAGE and Western blotting, the rheumatoid arthritic synovial cathepsin B was shown to exist in two forms with apparent molecular masses of M r 29 000 and 42 000. We propose that the former is a ftmctionally active proteinase, whereas the latter is a pepsin activatable proform which, when cleaved by this aspartyl proteinase, is converted into a catalytically competent species of M f 20000.