DAPT treatment resulted in the obvious downregulation of Th17 cell percentage in cocultured CD4+ T cells, RORγt and IL-17 mRNA levels, and IL-17 concentration in cell-free supernatant from cocultured CD4+ T cells of PV patients in a dose-dependent manner, while there was no significant influence on Treg cell percentage, Foxp3, and IL-10 expression, therefore leading to the recovery of Th17/Treg immune imbalance. The gene discussed is IL17A; the disease is acquired polycythemia vera.