title: Correlation of serum levels of adenosine deaminase activity and its isoenzymes with disease activity in rheumatoid arthritis.
abstract: OBJECTIVE
  Adenosine deaminase (ADA) is involved in purine metabolism and plays a significant role in the mechanisms of the immune system. The aim of this study was to investigate the correlation between the activity of total ADA (tADA) and isoenzymes ADA1 and ADA2 and clinical activity in patients with rheumatoid arthritis (RA).
  
  
  METHODS
  The study comprised 37 patients with rheumatoid arthritis and 30 healthy controls. Total serum ADA activity was measured spectrophotometrically. The isoenzyme pattern of ADA was analyzed using erytro-9-(2-hydroxy-3-nonyl) adenine (EHNA). Disease activity was assessed using DAS criterion.
  
  
  RESULTS
  The means of tADA, ADA1 and ADA2 levels were found to be 22.7 +/- 5.9, 3.9 +/- 2.0 and 18.8 +/- 4.9 IU/L in patients with RA, and 15.1 +/- 4.4, 4.1 +/- 1.2 and 11.0 +/- 3.7 IU/L in healthy control subjects. When compared to the healthy controls, serum tADA and ADA2 levels were significantly higher (p < 0.001) in patients with RA, but the decrease of ADA1 level was not statistically significant (p > 0.05). There was a strong correlation (r = 0.527, p < 0.001) between serum tADA level and disease activity by DAS (Pearson's rank correlation), and no correlation between tADA and CRP or ESR in the patient groups (p > 0.05).
  
  
  CONCLUSIONS
  Serum tADA and ADA2 activity is closely associated with RA and these non-invasive investigations can be used as biochemical markers for inflammation. These may provide additional information regarding disease activity along with the traditional indices such as ESR and CRP.
authors.affiliation: Department of Immunology/Rheumatology, Atatürk University, Medical School, Erzurum, Turkey. refikali@yahoo.com
authors.forename: R A
authors.initials: RA
authors.lastname: Sari
authors.forename: S
authors.initials: S
authors.lastname: Taysi
authors.forename: O
authors.initials: O
authors.lastname: Yilmaz
authors.forename: N
authors.initials: N
authors.lastname: Bakan
mesh_terms: D000243:Adenosine Deaminase / Q000097:blood*; D000328:Adult; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000201:enzymology* / Q000503:physiopathology; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000032:analysis; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000097:blood; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index
chemical_list: D007527:Isoenzymes; D002097:C-Reactive Protein; D000243:Adenosine Deaminase