Accumulation of a potent gammadelta T-cell stimulator after deletion of the lytB gene in Escherichia coli.
Eberl M,
Altincicek B,
Kollas AK,
Sanderbrand S,
Bahr U,
Reichenberg A,
Beck E,
Foster D,
Wiesner J,
Hintz M,
Jomaa H.
Biochemisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany. matthias.eberl@biochemie.med.uni-giessen.de
Activation of human Vgamma9/Vdelta2 T cells by many pathogens depends on the presence of small phosphorylated non-peptide compounds derived from the 2-C-methyl-d-erythritol 4-phosphate (MEP) pathway of isoprenoid biosynthesis. We here demonstrate that in Escherichia coli mutants deficient in lytB, an essential gene of the MEP pathway, a potent Vgamma9/Vdelta2 T-cell activator accumulates by a factor of approximately 150 compared to wild-type E. coli. The compound responsible for the strong immunogenicity of this E. coli mutant was subsequently characterized and identified as a small pyrophosphorylated metabolite, with a molecular mass of 262 Da, derived from the MEP pathway. Stimulation of human peripheral blood mononuclear cells (PBMC) with extracts prepared from the lytB-deficient E. coli mutant led to upregulation of T-cell activation markers on the surface of Vgamma9/Vdelta2 T cells as well as proliferation and expansion of Vgamma9/Vdelta2 T cells. This response was dependent on costimulatory growth factors, such as interleukin (IL)-2, IL-15 and IL-21. Significant levels of interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha) were secreted in the presence of IL-2 and IL-15, but not in the presence of IL-21, demonstrating that proliferating phosphoantigen-reactive Vgamma9/Vdelta2 T cells do not necessarily produce proinflammatory cytokines.
PMID: 12047749 [PubMed - indexed for MEDLINE]
PMCID: PMC1782719