The Influence of Phagocytosis on the Intracellular Distribution of Granule-associated Components of Polymorphonuclear Leucocytes

Control and phagocyting populations of rabbit polymorphonuclear leucocytes have been compared in terms of the content and distribution of phagocytin and selected hydrolytic enzymes. Following incubation at 37 degrees C., the cells were disrupted by homogenization and separated into an 8,200 g pellet and supernatant fluid. The high speed pellet from control leucocytes contained all the larger particulate elements of the cell including intact cytoplasmic granules. The ingestion of large numbers of heat-killed bacteria was accompanied by a fourfold reduction in the total phagocytin content of the leucocyte, whereas phagocytosis did not influence the recovery of histone-like bactericidin from nuclei. Engulfment of microorganisms led to a progressive decrease in the activity of phosphatases, beta glucuronidase, and cathepsin extractable from the 8,200 g pellet, with a concomitant increased activity of these enzymes in the supernatant fraction. No significant difference in the total enzyme content of control and phagocyting cells was noted. These findings are consistent with the lysis of granules following phagocytosis and the liberation of granule constituents into the cytoplasm of the leucocyte.