Glycosphingolipids as novel targets for T-cell suppression by the B subunit of recombinant heat-labile enterotoxin.

Infection and Immunity
R L TruittJ T Barbieri

Abstract

Heat-labile enterotoxin subunit B (LTB) is a noncatalytic protein derived from Escherichia coli that binds to ganglioside GM1, a glycosphingolipid on the surface of mammalian cells. In this study, the effects of recombinant LTB (rLTB) on murine lymphocytes were examined in vitro. T and B cells readily bound fluorescein isothiocyanate-labeled rLTB. CD8+ T cells bound twice as much as CD4+ T cells and B cells. Exposure of T-cell subsets and B cells to rLTB abrogated mitogen-driven proliferation. CD8+ T cells were more susceptible to rLTB than either CD4+ T cells or B cells. There were differences in the sensitivity of lymphocytes from various strains of mice to rLTB. This was attributed to qualitative and quantitative differences in the CD4+ T cells. rLTB induced apoptosis in both T-cell subsets, but the level was significantly higher in CD8+ T cells. Apoptosis peaked at around 8 h after exposure to rLTB and incubation at 37 degrees C. Binding to ganglioside GM1 was essential for suppression, since rLTB/G33D, a mutant which does not bind GM1, failed to inhibit proliferation or induce apoptosis. Naive T cells, which were acutely sensitive to rLTB, became more resistant after activation. Conversely, activated T cells regained their...Continue Reading

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Citations

Sep 6, 2008·Canadian Journal of Microbiology·Andréa da Silva Ramos RochaOdir Antônio Dellagostin
Jul 15, 2000·Oral Microbiology and Immunology·E GemmellG J Seymour
Aug 1, 2010·Toxins·Chiou-Feng LinMing-Yuan Hong
Jul 14, 2001·Trends in Biotechnology·E J RyanK H Mills
Mar 1, 2005·Vaccine·L C Freytag, J D Clements

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