Collection and Preservation of Synovial Fluids and Blood for Arthritis Research

Synovial fluids of patients with RA, juvenile idiopathic arthritis (JIA), gout or Lyme’s disease were collected in ethylenediaminetetraacetic acid (EDTA)-treated BD vacutainers (BD Biosciences, Franklin Lakes, NJ, U.S.A.). Each sample was centrifuged for 10 minutes at 400 g. Cell-free supernatant were collected and stored at -80°C. Platelet-free plasma was isolated after centrifugation of whole blood (collected in EDTA-treated vacutainers) for 20 minutes at 400 g, followed by 10 minutes of centrifuging the supernatant at 17000 g. Whole blood was collected in BD vacutainers SST and centrifuged at 800 g for 10 minutes to isolate serum. Synovial fluids were only collected upon need for joint aspiration and were provided by the rheumatology unit of the university hospital UZ Leuven. Ethical approval was granted by the local Ethics Committee of the University Hospitals Leuven (UZ Leuven) under numbers ML1814, S61878 and S65508. Patients and healthy blood donors provided informed consent according to the ethical guidelines of the Declaration of Helsinki.