Free Content Induction of necrosis and apoptosis of neutrophil granulocytes by Streptococcus pneumoniae

Authors: Zysk, G.1; Bejo, L.1; Schneider-Wald, B. K.1; Nau, R.2; Heinz, H.-P.1

Source: Clinical & Experimental Immunology, Volume 122, Number 1, October 2000 , pp. 61-66(6)

Publisher: Blackwell Publishing

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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.

Keywords: neutrophil cytology; PMN; cell death; pneumococcal cell walls; pneumolysin; hydrogen peroxide

Document Type: Research article

DOI: 10.1046/j.1365-2249.2000.01336.x

Affiliations: 1: Institute of Medical Microbiology and Virology, University of Düsseldorf, Düsseldorf, and 2: Department of Neurology, University of Göttingen, Göttingen, Germany

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