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Infection and Immunity, December 2000, p. 6770-6776, Vol. 68, No. 12
Department of Cancer Research and Molecular
Biology1 and Department of
Biotechnology, Norwegian University of
Science and Technology,3 and SINTEF, Division of Applied
Chemistry,2 Trondheim, Norway, and
Maxwell Finland Laboratory for Infectious Diseases, Department of
Medicine, Boston Medical Center and Boston University School of
Medicine, Boston, Massachusetts 021184
Received 26 June 2000/Returned for modification 24 August
2000/Accepted 18 September 2000
Lipopolysaccharide (LPS) and related bacterial products can be
recognized by host inflammatory cells in a particulate, bacterium-bound form, as well as in various soluble, released forms. In the present study we have compared the mechanisms used by LPS, detoxified LPS
(DLPS), and mannuronic acid polymers (M-polymers), in solution or
covalently linked to particles, in stimulating monocytes to tumor
necrosis factor (TNF) production. The addition of recombinant LPS
binding protein (LBP) and/or soluble CD14 (sCD14) enhanced the
production of TNF from monocytes stimulated with soluble LPS, DLPS, or
M-polymer, but did not affect the response to M-polymer or DLPS
attached to particles. Treatment of monocytes with antibody to CD14,
CD18, or CD11b showed that CD14, but not CR3 (CD11b/CD18), mediated
monocyte TNF production in response to the soluble antigens. In
contrast, anti-CD14, anti-CD11b and anti-CD18 monoclonal antibodies all
inhibited the response to the particulate stimuli. On the other hand,
B975, a synthetic analog of Rhodobacter capsulatus lipid A,
completely abrogated the monocyte TNF response induced by LPS but did
not affect the TNF induction by DLPS or M-polymer, either in soluble or
particulate forms. These data demonstrate that the engagement of immune
receptors by bacterial products such as LPS, DLPS, and M-polymer is
dependent upon the presentation form of their constituent
carbohydrates, and that factors such as aggregation state, acylation,
carbohydrate chain length, and solid versus liquid phase of bacterial
ligands influence the mechanisms used by cells in mediating
proinflammatory responses.
0019-9567/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Involvement of CD14 and
2-Integrins in
Activating Cells with Soluble and Particulate Lipopolysaccharides
and Mannuronic Acid Polymers
*
Corresponding author. Mailing address: Department of
Cancer Research and Molecular Biology, Norwegian University of Science and Technology, University Medical Center, N-7489 Trondheim, Norway. Phone: 47 73 59 88 41. Fax: 47 73 59 88 01. E-mail:
trude.flo{at}medisin.ntnu.no.
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