Volume 122, Issue 1 pp. 61-66

Induction of necrosis and apoptosis of neutrophil granulocytes by Streptococcus pneumoniae

G. Zysk

G. Zysk

Institute of Medical Microbiology and Virology, University of Düsseldorf, Düsseldorf, and

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L. Bejo

L. Bejo

Institute of Medical Microbiology and Virology, University of Düsseldorf, Düsseldorf, and

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B. K. Schneider-Wald

B. K. Schneider-Wald

Institute of Medical Microbiology and Virology, University of Düsseldorf, Düsseldorf, and

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R. Nau

R. Nau

Department of Neurology, University of Göttingen, Göttingen, Germany

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H.-P. Heinz

H.-P. Heinz

Institute of Medical Microbiology and Virology, University of Düsseldorf, Düsseldorf, and

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First published: 24 December 2001
Citations: 65
Dr Gregor Zysk, Department of Medical Microbiology and Virology, University of Düsseldorf, Geb. 22.21/U1, Universitätsstraße 1, D-40225 Düsseldorf, Germany. E-mail: [email protected]

Abstract

Apoptosis followed by macrophage phagocytosis is the principal mechanism by which neutrophil granulocytes (PMN) are removed from the site of inflammation. To investigate whether Streptococcus pneumoniae causes apoptosis of PMN, we exposed PMN to viable and heat-killed pneumococci and purified pneumococcal cell walls (PCW). The occurrence of PMN cell death was quantified by flow cytometry using annexin V/propidium iodide labelling of the cells. Intracellular histone-associated DNA fragments were quantified by ELISA. The presence of apoptosis was confirmed by in situ tailing. Exposure of PMN to viable pneumococci caused necrosis of the cells. The pneumococcal cytotoxin pneumolysin, the bacterial production of hydrogen peroxide, and PCW contributed to necrosis. Heat-killed pneumococci accelerated the process of apoptosis observed in cultivated non-stimulated PMN in vitro. These results demonstrated that pneumococci induce PMN cell death. Depending on the intensity of the stimulus, PMN necrosis and apoptosis were observed.

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