Article

Bacterial stimulation upregulates the surface expression of the stress protein gp96 on B cells in the frog Xenopus.

Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642, USA.
Cell Stress and Chaperones (impact factor: 3.01). 02/2003; 8(3):265-71. pp.265-71
Source: PubMed

ABSTRACT The presence of the soluble intracellular heat shock protein gp96 (an endoplasmic reticulum resident protein) at the surface of certain cell types is an intriguing phenomenon whose physiological significance has been unclear. We have shown that the active surface expression of gp96 by some immune cells is found throughout the vertebrate phylum including the Agnatha, the only vertebrate taxon whose members (lamprey, hagfish) lack an adaptive immune system. To determine whether gp96 surface expression can be modulated by pathogens, we investigated the effects of in vitro stimulation by purified lipopolysaccharide (LPS) and the heat-killed gram-negative bacteria, Escherichia coli and Aeromonas hydrophilia. Purified Xenopus B cells are readily activated and markedly proliferate in vitro in response to the heat-killed bacteria but not to purified LPS. Furthermore, messenger ribonucleic acid, and intracellular and surface protein expressions of both gp96 and immunoglobulin were upregulated only after activation of B cells by heat-killed bacteria. These data are consistent with an ancestral immunological role of gp96 as an antigen-presenting or danger-signaling molecule, or both, interacting directly with antigen-presenting cells, T cells, or natural killer cells, (or all), to trigger or amplify immune responses.

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Keywords

active surface expression
 
adaptive immune system
 
amplify immune responses
 
ancestral immunological role
 
antigen-presenting cells
 
B cells
 
certain cell types
 
endoplasmic reticulum resident protein
 
gp96 surface expression
 
heat-killed bacteria
 
heat-killed gram-negative bacteria
 
immune cells
 
messenger ribonucleic acid
 
natural killer cells
 
purified lipopolysaccharide
 
Purified Xenopus B cells
 
surface protein expressions
 
T cells
 
vertebrate taxon
 
vitro stimulation