Rapid secretion of intracellularly pre-stored interleukin-8 from rabbit platelets upon activation

Freshly isolated rabbit platelets contained a substantial amount of intracellular interleukin-8 (IL-8) as revealed by immunohistochemistry and Western blotting analysis. Thrombin stimulation at room temperature induced platelets to secrete IL-8 rapidly, and the maximal secretion was observed within 10 min after the activation, Secreted IL-8 possessed neutrophil chemotactic activity that was neutralized by a specific neutralizing monoclonal antibody to rabbit IL-8 but not a control one, These results suggest that rabbit platelets store biologically active IL-8 intracellularly and secrete it rapidly upon activation, This study implies that platelets may be a pivotal participant in inflammatory reactions in rabbits through producing cytokines and chemokines, including IL-8.