Leukotriene (LT) C
4 in the synovial fluid of patient with osteoarthritis deformans (OA) and rheumatoid arthritis (RA) was measured by radioimmunoassay after its extraction with Sep-Pak C
18 cartridge. The amounts of immunoreactive LTC
4 (i-LTC
4) in samples from patients with OA and RA were not significantly different, being 0.198±0.018 pmol/m
l (n=11) and 0.179±0. 016 pmol/m
l (n=12), respectively. By high performance liquid chromatography and radioimmunoassay, the levels of other sulfidopeptide LTs, such as LTD
4 and LTE
4, in synovial fluid from patients with RA were found to be significantly higher than those in fluid from patients with OA. The leukocyte number in synovial fluids was not correlated with the i-LTC
4 level.
The metabolic activities of these synovial fluids were determined by incubating them with
3H-LTC
4 and then separating sulfidopeptide LTs by high performance liquid chromatography. LTC
4 was found to be converted by γ-glutamyltranspeptidase activities to LTD
4 which was further metabolized by dipeptidase of synovial fluid to LTE
4. The conversion of LTC
4 to LTD
4 in synovial fluids of patients with OA and RA were similar, but the dipeptidase activity converting LTD
4 to LTE
4 was higher in fluid from patients with RA. It is suggested that a high level of LTE
4 may play cause exudation of synovial fluid, since LTE
4 has a strong effect in increasing vascular permeability.
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