Induction of interleukin (IL)-6, IL-8, and B cell-activating factor (BAFF) synthesis by microparticles (MPs) isolated from synovial fluids. Rheumatoid arthritis (RA) fibroblast-like synoviocytes were stimulated with 40 nM phosphatidylserine equivalents of MPs isolated from synovial fluids of osteoarthritis (OA) and RA patients for 24 and 72 hours. IL-6 (a), IL-8 (b), and BAFF (c) release was determined by enzyme-linked immunosorbent assay. Data are expressed as the mean of triplicate samples ± standard deviation and are representative of three independent experiments. C, control medium; IFN-γ, interferon-gamma; SN, control supernatants.