IFNA1 and Increased total leukocyte count: In JAK2V617F/Vav-Cre–transplanted mice, IFN-α treatment induced suppression of leukocytosis (p = 0.0023) and normalization of platelet count (p = 0.00238) and hematocrit (p = 0.0041) after 8 weeks of treatment (Fig. 5B-D), as previously reported [23, 29].