Infection and Immunity, August 1999, p. 4048-4054, Vol. 67, No. 8
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Centre d'Immunologie INSERM-CNRS de
Marseille-Luminy,
Received 29 December 1998/Returned for modification 9 March
1999/Accepted 4 May 1999
Lipopolysaccharide (LPS), a major amphiphilic molecule located at
the outer membrane of gram-negative bacteria, is a potent antigen known
to induce specific humoral immune responses in infected mammals. LPS
has been described as a polyclonal activator of B lymphocytes,
triggering the secretion of antibodies directed against distinct sugar
epitopes of the LPS chain. But, how LPS is handled by B cells remains
to be fully understood. This task appears to be essential for a better
knowledge of the anti-LPS humoral immune response. In this study, we
examine the internalization of LPS and its interaction with
antigen-presenting major histocompatibility complex (MHC) class II
molecules in murine and human B-cell lines. By use of
immunofluorescence, we observe that structurally different LPSs from
Brucella and Shigella strains accumulate in an
intracellular compartment enriched in MHC class II molecules. By use of
immunoprecipitation, we illustrate that only Brucella
abortus LPS associates with MHC class II molecules in a
haplotype-independent manner. Taken together, these results raise the
possibility that B. abortus LPS may play a role in T-cell activation.
*
Corresponding author. Mailing address: Centre
d'Immunologie INSERM-CNRS de Marseille-Luminy, Case 906-13288, Marseille Cedex 9, France. Phone: (33) 4-91-26-94-66. Fax: (33)
4-91-26-94-30. E-mail: gorvel{at}ciml.univ-mrs.fr.
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