P387 TSP-4 enhances release of hydrogen peroxide from PMNs. PMNs were untreated or stimulated with 1 nM PMA for 20 minutes at 37°C and allowed to adhere to TSP-4–coated plates for 4 hours at 37°C. Hydrogen peroxide levels were measured in conditioned media using an Amplex Red Assay Kit. The data are means ± SEMs with neutrophils from 4 blood donors with quadruplet measurements made in each assay.