ELECTRON MICROSCOPIC STUDY OF PHAGOCYTOSIS OF STAPHYLOCOCCUS BY HUMAN LEUKOCYTES II

Abstract

Techniques of ultra-thin sectioning of human leukocytes were used to examine the relationship between leukocytes and ingested bacteria. Virulent and non-virulent strains of Staphylococcus aureus were mixed with suspensions of human buffy coat and incubated at 37[degree]C. Aliquots were removed at 5 minutes, 15 minutes, 30 minutes, 1-hour and 2-hour intervals for fixation, dehydration, embedding and sectioning. Bacteria were noted on the surface of the leukocytes and in various stages of phagocytosis. The non-virulent strain is destroyed by leukocytes. The osmophilia of the organisms decreases as the bacteria are digested. Vacuolation develops within the bacteria during digestion and the bacterial cell wall is one of the last identifiable structures. The virulent strain ingestion results in development of vacuoles about the bacteria, retention of their osmophilia and some bacterial fission within the cytoplasm of the neutrophils. Continued growth of the bacteria results in large vacuoles in the neutrophils with subsequent rupture and eventual destruction of the leukocyte. Lymphocytes present in the suspension apparently are unaffected during the 2-hour incubation.