Sp-a enhances phagocytosis of klebsiella by interaction with
capsular polysaccharides and alveolar macrophages.
Kabha, Kisra, Jutta Schmegner, Yona Keisari, Haralambos Parolis, Jutta
Schlepper-Schaefer, Itzhak Ofek.
Department of Human Microbiology, Sackler Faculty of Medicine, Tel
-Aviv University, Tel-Aviv, Israel 69978, Faculty of Biology,
University of Konstanz, D-78434 Konstanz, Germany, School of
Pharmaceutical Sciences, Rhodes University, Grahamstown 6140, South
Africa
APStracts 3:0160L, 1996.
We found that surfactant protein A (SP-A) enhances phagocytosis of
Klebsiella pneumoniae K21a but not of K2 serotypes by alveolar
macrophages. SP-A interacted with the capsule of K21a (containing
Man[alpha]1Man sequences) as shown by SP- A induced agglutination of
the bacteria, binding of SP-A coated particles onto the bacterial
surface and by binding of SP-A to immobilized parent K21a strain and
recombinant strains that switched their capsule from K2 to K21a . In
contrast, only marginal binding of SP-A to K2 parent strain (lacking
this sequence) could be detected. Furthermore, binding of capsular
polysaccharide of K21a to immobilized SP-A was inhibited by mannan
but not by LPS and K2 capsular polysaccharide. SP-A treated
macrophages bound increased numbers of parent K21a strain and
recombinant strains of K21a capsule type but considerably less parent
K2 strain. SP-A also enhanced killing of K21a strains by macrophages.
The enhanced binding of K21a by macrophages pretreated with SP-A was
inhibited by mannan, suggesting that binding is mediated by the
mannose receptor on macrophages. We conclude that SP-A increases
phagocytosis of the Klebsiella by two mechanisms one of which is by
serving as an opsonin which binds to the capsular polysaccharides of
the bacteria and potentially to SP-A receptors on the macrophages and
the other by activating the macrophages resulting in increased
activity of the mannose-receptor.
Received 10 January 1996; accepted in final form 19 September
1996.
APS Manuscript Number L9-6.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 7 October 1996