Anti-inflammatory effects of human PMN–derived microparticles. Annexin 1 (AnxA1)–rich microparticles are anti-inflammatory. Mice received 200 μL saline intravenously or 2 doses of human PMN–derived microparticles, or human recombinant AnxA1 (10 μg; positive control), immediately before the local injection of mouse IL-1β into 6-day-old air pouches. The extent of cell migration was determined 4 hours later, following air pouch washing and staining of migrated cells with Gr1 marker. Data are mean plus or minus SEM of 5 mice per group. *P < .05 versus vehicle group.