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

Freshly isolated rabbit platelets con- tamed a substantial amount of intracellular inter- leukin-8 (IL-B) as revealed by immunohistochemiatry and Western blotting analy- ste. Thrombin stimulation at room temperature in- duced platelets to secrete IL-B rapidly, and the maximal secretion was observed within iO mm after the activation. Secreted IL-B 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. J. Leukoc. Biol. 59: 420-426; 1996.