Induction of interleukin (IL)-6, IL-8, and B cell-activating factor (BAFF) synthesis by microparticles (MPs) isolated from CEM lymphocytes. Rheumatoid arthritis fibroblast-like synoviocytes were stimulated with 40 and 400 nM phosphatidylserine equivalents of MPs isolated from CEM lymphocytes treated either with actinomycin D (ActD) alone (0.5 μg/mL) for 18 hours or with a combination of PHA, PMA and Adt-D (PPA) (phytohemagglutinin) (5 μg/mL) for 72 hours followed by ActD (0.5 μg/mL) and phorbolmyristate acetate (20 ng/mL) for an additional 18-hour incubation period. Culture supernatants were harvested 24 hours after stimulation for IL-6 (a) and IL-8 (b) determination and 72 hours after stimulation for BAFF evaluation (c) by enzyme-linked immunosorbent assay. Lipopolysaccharide (IL-6 and IL-8) and interferon-gamma (IFN-γ) (BAFF) stimulation was used as a positive control. Data are expressed as the mean of triplicate samples ± standard deviation and are representative of three independent experiments. **P < 0.01. Act, actinomycin; C, control medium; Pser, phosphatidylserine; TMP, control Hanks' balanced saline solution.