IL17A and infection: Signature cytokines of Th17 cells include IL-17A, IL-17F, IL-22, and IL-26 (specific for humans) and these canonical cytokines produced by the classical Th17 (CD4+ IL-17 producing cells) and non-Th17 cells including γδ-T cells and innate lymphoid cells play critical roles in regulating tissue homeostasis and inflammation as well as antimicrobial responses upon infections caused by pathogens.