IL17A and hand, foot and mouth disease: In conclusion, our results showed that the frequencies of cTh22 cells and associated cells (cTh17), the expression of cTh22 cells and associated cytokines (IL-22, IL-17A, TNF-α, IL-6 and IL-23) and transcription factors (AHR and RORγt) were significantly increased in the patients with EV71-associated HFMD, particularly in severe patients compared to HC.