Scanning electron microscopic observations of early stages of phagocytosis of E. coli by human neutrophils |
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Authors: | Edith K. MacRae Katherine B. Pryzwansky Marjorie H. Cooney John K. Spitznagel |
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Affiliation: | (1) Department of Anatomy, University of North Carolina, Chapel Hill, North Carolina, USA;(2) Department of Bacteriology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA;(3) Department of Anatomy, University of North Carolina, 27514 Chapel Hill, North Carolina, USA;(4) Present address: Department of Molecular, Cellular and Developmental Biology, University of Colorado, 80309 Boulder, Colorado, USA;(5) Present address: Department of Microbiology, Emory University School of Medicine, 30322 Atlanta, Georgia, USA |
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Abstract: | Summary Changes in surface morphology, as observed by scanning electron microscopy, appear rapidly when human polymorphonuclear neutrophils (PMN) are challenged with bacteria. Monolayers of PMN adhering to glass were incubated with opsonized E. coli from 5 sec to 10 min, and then fixed and prepared for SEM. As early as 5 sec after phagocytic challenge, E. coli are found in contact with PMN and in the process of engulfment into open cavities formed by lamellipodia. The shape of the mouth of the forming phagocytic vacuole is related to the orientation of bacteria during entry. Bacteria engulfed into early forming phagosomes are surrounded by a large open space between the bacteria and the phagosome wall. As phagocytosis proceeds, the space is reduced and the loose fit around the entering bacteria becomes tight. By 30 sec, bacteria may be completely internalized and by 1 min phagocytized E. coli are packed into bulging PMN. The observations reveal the variability and rapidity of the phagocytic response and confirm the presence of sensitive mechanisms for host defense by PMN.This work was supported by research grants from the University of North Carolina Research Council and the National Institutes of Health (A1 02430) |
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Keywords: | Phagocytosis Human polymorphonuclear leukocytes Neutrophils E. coli Scanning electron microscopy |
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