Degranulation and enzyme release during phagocytosis of inert particles and of bacteria by polymorphonuclear neutrophil granulocytes.

The degranulation and release of lysosomal (myeloperoxidase, beta-glucuronidase, lysozyme) and cytoplasmic (lactate dehydrogenase-LDH) enzymes from polymorphonuclear neutrophil granulocytes (PMG) during phagocytosis of inert latex particles or bacteria were studied. Degranulation was much faster and more pronounced by phagocytosis of bacteria than of inert particles. A high frequency of lysosome-lysosome as well as lysosome-phagosome fusions suggested that granular material was transported by lysosome- lysosome- phagosome fusions. During bacterial phagocytosis there was evidence of release of granular material into cytoplasm causing enzymatic disintegration. After 60 minutes cell lysis occurred in about 5 per cent of the cells during bacterial phagocytosis. There was non-specific release of LDH during phagocytosis of inert particles, probably due to erythro-phagocytosis. After 60 minutes the release during bacterial phagocytosis amounted to 20-30 per cent of the enzyme content of the cells. A nearly equal release of lysosomal and cytoplasmic enzymes gave support for the idea that cell lysis was the main mechanism of enzyme release.