IL17A and acute lymphoblastic leukemia: Additionally, serum concentrations of IL-17 and IL-21 showed positive correlation with circulating Th17 cells in both ALL (r = 0.768, P < 0.0001, r = 0.548, P < 0.0001 for IL-17 and IL-21, respectively) and AML patients (r = 0.897, P < 0.0001, r = 0.765, P < 0.0001 for IL-17 and IL-21, respectively).