Early production of IL-17A by γδ T cells in the trachea promotes viral clearance during influenza infection in mice.

The innate immune response generated against influenza infection is critical for the inhibition of viral dissemination. The trachea contains different types of innate immune cells that protect the respiratory tract from pathogen invasion. Among them, gamma delta T cells have the ability to rapidly generate large amounts of pro-inflammatory cytokines to preserve mucosal barrier homeostasis during infection. However, little is known about their role during the early phase of influenza infection in the airways. In this study, we found that, early after infection, gamma delta T cells are recruited and activated in the trachea and outnumber alpha beta T cells during the course of the influenza infection that follows. We also showed that the majority of the recruited gamma delta T cells express the V gamma 4 TCR chain and infiltrate in a process that involves the chemokine receptor CXCR3. In addition, we demonstrated that gamma delta T cells promote the recruitment of protective neutrophils and NK cells to the tracheal mucosa. Altogether, our results highlight the importance of the immune responses mediated by gamma delta T cells.