Association between severity of knee osteoarthritis and serum and synovial fluid interleukin 17 concentrations

Objective To determine interleukin (IL)-17 concentrations in serum and synovial fluid from patients with knee osteoarthritis, and evaluate their correlation with disease severity. Methods Serum and synovial fluid were collected from patients with primary knee osteoarthritis; age- and sex-matched healthy control subjects provided serum samples. This study was conducted retrospectively. IL-17 was quantified by enzyme-linked immunosorbent assay. Osteoarthritis severity and grade were assessed using the Lequesne index and Kellgren and Lawrence (KL) grading system, respectively. Results Serum IL-17 concentrations were significantly higher in patients (n=98) than in controls (n=50). In the patient group, the synovial fluid IL-17 concentration increased significantly with KL grade and was significantly positively correlated with Lequesne index (r=0.6232). Conclusions The synovial fluid IL-17 concentration could represent a useful biochemical marker to reflect knee osteoarthritis severity and progression.