Differential activation of chicken gamma delta T cells from different tissues by Toll-like receptor 3 or 21 ligands

Gamma delta (gamma delta) T cells are highly enriched in mucosal barrier sites including intestinal tissues where microbial infections and tumors often originate in mammals. Human gamma delta T cells recognize stress antigens and microbial signals via their T cell receptor (TCR), natural killer (NK) receptors, and pattern recognition receptors. However, little is known about antigens or ligands capable of stimulating chicken gamma delta T cells. The results of the present study demonstrated that polyinosinic-polycytidylic acid (poly(I:C)), a Toll-like receptor (TLR)3 ligand, significantly induced upregulation of CD8 alpha molecules on circulating and lung gamma delta T cells. Moreover, poly(I:C) stimulation induced interferon (IFN)-gamma production from splenic and lung CD8 alpha+ gamma delta T cells while Cytosine-phosphate-Guanine oligodeoxynucleotides (CpG-ODN) 2007, a TLR21 ligand, stimulation induced IFN-gamma production by circulating gamma delta T cells. Neither poly(I:C) nor CpG-ODN 2007 stimulation elicited degranulation of gamma delta T cells. Additionally, the results revealed that CpG-ODN 2007 induced IFN-gamma production from TCR-stimulated gamma delta T cells sorted from spleen. In our experiments, isopentenyl pyrophosphate (IPP), 4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBPP), or zoledronate (Zol) stimulation did not induce IFN-gamma production or degranulation in gamma delta T cells. Taken together, a combination of CpG-ODN 2007 and anti-CD3e monoclonal antibodies (mAbs) can stimulate chicken gamma delta T cells and induce production of IFN-gamma by these cells while IFN-gamma production by gamma delta T cells induced by stimulation of poly(I:C) needs signals from other cells. These results suggest that chicken gamma delta T cells can sense invading pathogens via TLRs and produce IFN-gamma as a first line of defense.

Automated summary

Gamma delta (γδ) T cells can sense invading pathogens and produce interferon (IFN)-γ as a first line of defense. This study found that polyinosinic-polycytidylic acid (poly(I:C)) and CpG-ODN 2007 can stimulate chicken γδ T cells and induce IFN-γ production.