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Infection and Immunity, August 1999, p. 4264-4267, Vol. 67, No. 8
Department of Molecular Genetics,
Received 1 March 1999/Returned for modification 23 April
1999/Accepted 20 May 1999
To explore the role of neutrophil phagocytosis in host defense
against Bordetella pertussis, bacteria were labeled
extrinsically with fluorescein isothiocyanate (FITC) or genetically
with green fluorescent protein (GFP) and incubated with adherent human
neutrophils in the presence or absence of heat-inactivated human immune
serum. In the absence of antibodies, FITC-labeled bacteria were located primarily on the surface of the neutrophils with few bacteria ingested.
However, after opsonization, about seven times more bacteria were
located intracellularly, indicating that antibodies promoted
phagocytosis. In contrast, bacteria labeled intrinsically with GFP were
not efficiently phagocytosed even in the presence of opsonizing
antibodies, suggesting that FITC interfered with a bacterial defense.
Because FITC covalently modifies proteins and could affect their
function, we tested the effect of FITC on adenylate cyclase toxin
activity, an important extracellular virulence factor. FITC-labeled
bacteria had fivefold-less adenylate cyclase toxin activity than did
unlabeled wild-type bacteria or GFP-expressing bacteria, suggesting
that FITC compromised adenylate cyclase toxin activity. These data
demonstrated that at least one extracellular virulence factor was
affected by FITC labeling and that GFP is a more appropriate label for
B. pertussis.
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Fluorescent Labels Influence Phagocytosis of
Bordetella pertussis by Human Neutrophils
*
Corresponding author. Mailing address: Department of
Molecular Genetics, Biochemistry, and Microbiology, 231 Bethesda Ave., ML 524, University of Cincinnati College of Medicine, Cincinnati, OH
45267-0524. Phone: (513) 558-2820. Fax: (513) 558-8474. E-mail: Alison.Weiss{at}uc.edu.
Infection and Immunity, August 1999, p. 4264-4267, Vol. 67, No. 8
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
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