Toll like receptor 2 agonists lipoteichoic acid and peptidoglycan are able to enhance antigen specific IFN gamma release in whole blood during recall antigen responses

作者：Dammermann Werner^*; Wollenberg Lisa; Bentzien Frank; Lohse Ansgar; Lueth Stefan

来源：Journal of Immunological Methods, 2013, 396(1-2): 107-115.

DOI：10.1016/j.jim.2013.08.004

• Toll like receptor
• Agonist
• Interferon gamma release assay
• Lipoteichoic acid
• Peptidoglycan

Background: Interferon gamma release assays (IGRA) have been developed to support the diagnosis of diseases like tuberculosis, which lack robust serological test systems. IGRAs focus on cellular immunity especially memory T cells and thus complement serological testing. However, the low frequency of antigen-specific memory T cells in peripheral blood limits IFN gamma production to minute amounts and constitutes a major challenge for downstream test systems. We hypothesized that certain toll like receptor (TLR) agonists might enhance IFN gamma production in IGRAs after antigen challenge without inducing background cytokine production. In addition, we investigated the potential use of 112 release after TLR agonist application as another surrogate marker in cytokine release assays.
Methods: 176 healthy controls (HC) were tested for IFN gamma- and IL2-secretion in whole blood in the presence of different TLR agonists with and without antigen challenge by ELISA. The selected TLR agonists were lipopolysaccharide (LPS (sic) TLR4), lipoteichoic acid (LTA (sic) TLR2), peptidoglycan (PGN (sic) TLR2), zymosan (Zym (sic) TLR2 and 6), polyinosinic-polycytidylic acid (Poly I:C (sic) TLR3), flagellin (Ha (sic) TLR5), R848 ((sic)TLR7 and 8), loxoribine (Lox (sic) TLR7) and bropirimine (Bro (sic) TLR7).
Results: TLR2 agonists LTA and PGN increased IFIN gamma secretion after antigen challenge nearly twofold (740 vs. 443 pg/ml for LTA and 969 vs. 469 pg/ml for PGN, respectively) without eliciting higher background expression. TLR3 agonist Poly(I:C) andll.R5 agonist Fla also induced a twofold increase in IFN gamma synthesis (2.230 vs. 1.085 pg/ml for Poly(I:C) and 518 vs. 278 pg/ml for Fla, respectively), but background expression was slightly increased (114 vs. 7 pg/ml for Poly(I:C) and 47 vs. 12 pg/ml for Ha, respectively). 112 production was not increased after antigen challenge in the presence of LTA, PGN, Poly(I:C) or Fla. The agonists LPS, Zym, R848, Lox and Bro did not raise cytokine synthesis after antigen challenge or they generated high levels of cytokines by themselves.
Conclusion: Of all tested agonists TLR2-specific LTA and PGN met the requirements to increase IFIN gamma synthesis in whole blood after challenge with recall antigens without heightening basal cytokine levels alone. Thus, they constitute a potential costimulating reagent for IGRAs. IL2 did not show any potential as a surrogate marker in cytokine release assays in combination with TLR agonists.

• 出版日期2013-10-31