PT  - JOURNAL ARTICLE
AU  - PASCAL RICHETTE
AU  - MATHIAS FRANÇOIS
AU  - ERIC VICAUT
AU  - CATHERINE FITTING
AU  - THOMAS BARDIN
AU  - MAÏTÉ CORVOL
AU  - JEAN-FRANÇOIS SAVOURET
AU  - FRANÇOIS RANNOU
TI  - A High Interleukin 1 Receptor Antagonist/IL-1β Ratio Occurs Naturally in Knee Osteoarthritis
DP  - 2008 Aug 01
TA  - The Journal of Rheumatology
PG  - 1650--1654
VI  - 35
IP  - 8
4099  - http://www.jrheum.org/content/35/8/1650.short
4100  - http://www.jrheum.org/content/35/8/1650.full
SO  - J Rheumatol2008 Aug 01; 35
AB  - Objective To assess the interleukin 1 receptor antagonist (IL-1Ra)/IL-1β ratio in synovial fluid (SF) of patients with knee osteoarthritis (OA) or rheumatoid arthritis (RA) to determine a possible relation between cytokine level and disease activity. Methods IL-1β and IL-1Ra concentrations were measured by ELISA in knee SF from patients with OA (n = 42) or RA (n = 11). For OA patients, pain and disability were assessed by a visual analog scale (VAS) and the Lequesne index. RA disease activity was assessed using the Disease Activity Score 28 Joint Count (DAS28). Results Patients with OA showed lower median levels of IL-1β and IL-1Ra in SF than patients with RA (p < 0.001) but a higher IL-1Ra/IL-1β ratio: 1793 (584–6221) versus 773.5 (187.64–1570.5) (p = 0.05). For patients with OA, the IL-1Ra/IL-1β ratio was not associated with pain or disability. For patients with RA, the IL-1Ra/IL-1β ratio and IL-1Ra and IL-1β levels were related to SF white blood cell count. Conclusion High endogenous IL-1Ra/IL-1β ratio occurs in SF from knee OA and does not correlate with pain or Lequesne index. Our results suggest that intraarticular injection of IL-1Ra might be self-limited in patients with knee OA and a naturally high SF ratio.