title: Inactivation of antithrombin III in synovial fluid from patients with rheumatoid arthritis.
abstract: OBJECTIVE
  To investigate the thrombin inhibitory capacity of antithrombin III in the inflamed human joint.
  
  
  METHODS
  Thrombin inhibitory capacity was measured, using a kinetic spectophotometric method, in matched plasma and synovial fluid samples of patients with rheumatoid arthritis (n = 22) and osteoarthritis (n = 16), together with normal control plasma samples (n = 13). In the same samples, the concentration of antithrombin III was also determined by the method of radial immunodiffusion. The combination of these measurements allowed the calculation of the specific thrombin inhibitory capacity of these samples.
  
  
  RESULTS
  An increased concentration of antithrombin III in rheumatoid compared with osteoarthritic synovial fluid was noted (p < 0.05). However, there was a significant depression in the specific activity of antithrombin III in rheumatoid synovial fluid when compared with matched plasma samples (p < 0.001) or with osteoarthritic synovial fluid (p < 0.05).
  
  
  CONCLUSIONS
  In rheumatoid synovial fluid the thrombin inhibitory capacity of antithrombin III is disproportionately depressed relative to the concentration of antithrombin III, indicating the inactivation of antithrombin III in the rheumatoid joint.
authors.affiliation: Department of Rheumatology, Royal Hampshire County Hospital, Winchester.
authors.forename: H W
authors.initials: HW
authors.lastname: Jones
authors.forename: R
authors.initials: R
authors.lastname: Bailey
authors.forename: Z
authors.initials: Z
authors.lastname: Zhang
authors.forename: K A
authors.initials: KA
authors.lastname: Dunne
authors.forename: D R
authors.initials: DR
authors.lastname: Blake
authors.forename: N L
authors.initials: NL
authors.lastname: Cox
authors.forename: C J
authors.initials: CJ
authors.lastname: Morris
authors.forename: P G
authors.initials: PG
authors.lastname: Winyard
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000990:Antithrombin III / Q000037:antagonists & inhibitors*; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000378:metabolism*; D005260:Female; D006801:Humans; D005779:Immunodiffusion; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000097:blood / Q000378:metabolism; D013053:Spectrophotometry; D013582:Synovial Fluid / Q000378:metabolism*; D013917:Thrombin / Q000378:metabolism*
chemical_list: D000990:Antithrombin III; D013917:Thrombin