title: Comparison of serum and synovial fluid concentrations of beta 2-microglobulin and C reactive protein in relation to clinical disease activity and synovial inflammation in rheumatoid arthritis.
abstract: beta 2-Microglobulin and C reactive protein (CPR) were measured in 33 and 57 matched pairs of serum and synovial fluid (SF) respectively, from patients with active rheumatoid arthritis (RA). Serum beta 2-microglobulin concentrations were higher than in normal controls and the SF concentration was higher than the serum concentration on 25 of 33 occasions (76%), suggesting a local production of beta 2-microglobulin within the synovial membrane. There was a correlation between serum and SF concentrations of beta 2-microglobulin (r = 0.50). Patients' serum CRP concentrations in 57 samples were higher than in normal controls and were greater than in the matched SFs on 49 of the 57 paired samples (86%). In 18 samples CRP was absent in the SF, suggesting a local consumption or binding within the synovial membrane. Twenty four patients with RA given either sodium aurothiomalate or D-penicillamine for six months showed highly significant clinical improvements accompanied by reductions in serum and SF immunoglobulin concentrations and knee joint suprapatellar pouch synovial membrane T lymphocyte infiltrates. In this group of patients serum CRP, but not beta 2-microglobulin, fell significantly, but there were no significant changes in SF beta 2-microglobulin or CRP. These data suggest that serum and SF beta 2-microglobulin concentrations are not a useful index for determining the therapeutic response to sodium aurothiomalate and D-penicillamine and that serum rather than SF CRP concentrations are more helpful. The persistent raised serum and SF concentrations of beta 2-microglobulin probably reflect synovial inflammatory infiltrates, which are still considerable despite apparent clinical remission.
authors.affiliation: Rheumatology Unit, Southampton General Hospital.
authors.forename: M T
authors.initials: MT
authors.lastname: Walters
authors.forename: F K
authors.initials: FK
authors.lastname: Stevenson
authors.forename: R
authors.initials: R
authors.lastname: Goswami
authors.forename: J L
authors.initials: JL
authors.lastname: Smith
authors.forename: M I
authors.initials: MI
authors.lastname: Cawley
mesh_terms: D001172:Arthritis, Rheumatoid / Q000188:drug therapy / Q000378:metabolism*; D002097:C-Reactive Protein / Q000032:analysis*; D006052:Gold Sodium Thiomalate / Q000627:therapeutic use; D006801:Humans; D007719:Knee Joint / Q000378:metabolism; D010396:Penicillamine / Q000627:therapeutic use; D013582:Synovial Fluid / Q000032:analysis*; D013583:Synovial Membrane / Q000378:metabolism; D013995:Time; D001613:beta 2-Microglobulin / Q000032:analysis*
chemical_list: D001613:beta 2-Microglobulin; D006052:Gold Sodium Thiomalate; D002097:C-Reactive Protein; D010396:Penicillamine