TITLE

Immune-Mediated Phagocytosis and Killing of Streptococcus pneumoniae Are Associated with Direct and Bystander Macrophage Apoptosis

AUTHOR(S)
Dockrell, David H.; Lee, Margaret; Lynch, David H.; Read, Robert C.
PUB. DATE
September 2001
SOURCE
Journal of Infectious Diseases;9/15/2001, Vol. 184 Issue 6, p713
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Apoptosis of macrophages may be a pathogen-directed mechanism of immune escape or may represent appropriate host response to infection. Human monocyte-derived macrophages (MDMs) from healthy donors (C-MDMs) exhibited low-level constitutive apoptosis, but culture of MDMs with opsonized serotype I Streptococcus pneumoniae (I-MDMs) for 20 h resulted in significantly increased apoptosis. I-MDM apoptosis was associated with phagocytosis of bacteria and intracellular killing that was blocked by the caspase inhibitor z-VAD-fmk but not by Fas-blocking antibody. Paraformaldehyde-fixed I-MDMs induced apoptosis in uninfected syngeneic monocytes at levels greater than those in monocytes incubated alone or incubated with fixed C-MDMs. Apoptosis of syngeneic monocytes was blocked by anti-Fas antibody. The immune response of macrophages to S. pneumoniae includes a novel form of apoptosis that is associated with successful phagocytosis and bacterial killing. This response in vivo may regulate the inflammatory response to infection during a successful host response against S. pneumoniae.
ACCESSION #
5507059

 

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