?d T Cells Provide Protective Function in Highly Pathogenic Avian H5N1 Influenza A Virus Infection

Dong, Peng; Ju, Xiangwu; Yan, Yiwu; Zhang, Siya; Cai, Menghua; Wang, Huaishan; Chen, Hui; Hu, Yu; Cui, Lianxian; Zhang, Jianmin; He, Wei

Consistent with the integration of the HPAI H5N1 virus, substantial agglutination of freshly isolated primary human γδ T cells was observed after incubation with HAF but not with HA-his proteins ( Figure 4A) . However, the agglutination of γδ T cells was not observed when HAF proteins were treated with proteinase K (Figure 4A) . After γδ T cells were stimulated with HAF proteins, the expression level of CD69 on γδ T cells significantly increased. However, the expression level of CD69 increased slightly after γδ T cells were stimulated with HA-his proteins ( Figure 4B) . Furthermore, IFN-γ production markedly increased in a dose-dependent manner after γδ T cells were stimulated with HAF but not with HA-his proteins, and the stimulating effect of HAF proteins disappeared after proteinase K treatment ( Figure 4C) . As a key triggering signal, an increase in the intracellular free calcium concentration is rapidly induced upon γδ T cell activation (24) . Consistent with anti-CD3 mAb treatment, delayed Ca 2+ responses were observed in γδ T cells after incubation with HAF but not with HA-his proteins ( Figure 4D) . Taken together, these results suggest that rH5HA trimers but not the monomers could directly induce the agglutination and the activation γδ T cells.