A study on phagocytosis of radio-labeled Staphylococcus epidermidis and on structural events during intracellular degradation

Abstract

A simplified system has been used to study the events during and after the in vitro ingestion of Staphylococcus epidermidis by mouse peritoneal polymorphonuclear leucocytes (PMN's). ¹⁴C-labeled bacteria were incubated with PMN's in phosphate-buffered, physiological saline without the addition of divalent cations or serum. PMN's appeared to be saturated within 15 min after having each engulfed about nine bacteria (on the average).Electron micrographs of thin sections from specimens taken after bacteria and PMN's had been incubated together for 15 min revealed intracellular staphylococci in various states of degradation. The fragmentation of the cytoplasmic membrane was apparently one of the early events in cell degradation. Several other morphological events were also observed in disintegrating cells, e.g. agglomeration of the cytoplasm; loss of cell-wall rigidity, an apparent digestion of the cell wall from the outside; and the release of membrane vesicles into the phagocytic vacuole.