The Immunologic Release of Constituents from Neutrophil Leukocytes

Abstract

Abstract The reaction of rabbit neutrophils with immune complexes induced release of constituents to the external medium. The release which accompanied adherence of neutrophils to immune complexes bound to a nonphagocytosable surface resulted from a direct extrusion of granules to the exterior of the cell. Alkaline phosphatase from the secondary granule was released before constituents of the primary granule and remained at the site of excretion, adherent to the external neutrophil membrane. In contrast, while phagocytosis of particulate complexes stimulated release of materials from the primary granules, alkaline phosphatase was released in only small amounts. A possible mechanism of enzyme release during phagocytosis of large particles was demonstrated to occur by two steps. Degranulation into the phagocytic vacuole was followed by opening of the vacuole during uptake of additional particles. Neutrophils were not lysed during either release process.