Gene expression profiles in synovial biopsies from patients with arthritis

GeneChip® Human Genome U133 Plus 2.0 Arrays (Affymetrix UK Ltd., High Wycombe, UK) were hybridized in monoplicates with 10 μg biotinylated cRNA, using synovial biopsy samples obtained in 4 patients with SA (based on the presence of psoriasis or x-ray evidence of sacro-iliacal joint involvement), 5 patients with MIC, based on the identification of urate or calcium pyrophosphate crystals in the synovial fluid, 7 patients with RA (ACR 1987 criteria), 4 patients with SLE (ACR criteria) and 5 patients with OA (based on x-ray evidence of osteoarthritis)