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Infect. Immun., Mar 1995, 833-839, Vol 63, No. 3
JR Rose, WJ Christ, JR Bristol, T Kawata and DP Rossignol
Lipid A from the photosynthetic bacterium Rhodobacter sphaeroides (RSLA)
has been previously shown to antagonize many of the effects of endotoxins
from more pathogenic gram-negative bacteria. We have reported on the
synthesis of the proposed structure of RSLA and determined that bacterially
derived RSLA is not identical to its proposed structure (W.J. Christ, P. D.
McGuinness, O. Asano, Y. Wang, M. A. Mullarkey, M. Perez, L. D. Hawkins, T.
A. Blythe, G. R. Dubuc, and A. L. Robidoux, J. Am. Chem. Soc.
116:3637-3638, 1994). Here we report results of analyzing the antagonistic
and agonistic activities of bacterially derived RSLA in comparison with the
activities of chemically synthesized material of the proposed structure of
RSLA and analogs. Results indicated that all compounds were approximately
equally potent at inhibiting endotoxin-induced release of tumor necrosis
factor alpha from human monocytes and human whole blood as well as
endotoxin-induced generation of nitric oxide in murine macrophages. In
addition, all compounds were of equivalent potencies at inhibiting the
binding of 125I-labelled lipopolysaccharide derivatized with
2-(p-azido-salicylamido) ethyl-1-3'-dithiopropionate to murine macrophages.
Higher concentrations of bacterially derived RSLA (10 to 100 microM) were
agonistic in human and murine assays. In gamma interferon-treated murine
macrophages, agonism was exhibited at concentrations as low as 100 nM. In
contrast, all synthetic materials were either dramatically less agonistic
or devoid of agonistic activity when tested at concentrations as high as
100 microM. It is possible either that bacterially derived RSLA contains a
small amount of a highly agonistic impurity or that the agonistic activity
of RSLA is intrinsic to its molecular structure. In either case, these
biological results support our previous report concluding that biologically
derived RSLA is not identical to synthetic material of its proposed
structure.
Copyright © 1995, American Society for Microbiology
Agonistic and antagonistic activities of bacterially derived Rhodobacter sphaeroides lipid A: comparison with activities of synthetic material of the proposed structure and analogs
Section of Biology, Eisai Research Institute, Andover, Massachusetts 01810-2441.
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