KLF2 levels in platelets are inversely correlated with neutrophil and platelet counts and increased with PegINF-α treatment.KLF2 transcript level in platelets was inversely correlated with (A) neutrophil counts and (B) platelet counts but not with (C) hematocrit and (D) hemoglobin concentration. KLF2 transcript levels were measured in (E) platelets and (F) neutrophils before and after PegINF-α or HU. Changes of (G) neutrophil counts and (H) platelets counts were calculated against before treatment which was taken as 100% and inversely correlated with changes of KLF2 transcript levels in platelets. Changes of (I) neutrophil counts and (J) platelets counts were calculated against before treatment which was taken as 100% and inversely correlated with changes of KLF2 transcript levels in neutrophils. P value was calculated by paired t test. Correlation analysis was performed by Spearman correlation using GraphPad prism. ∗∗ P < .01, ∗ P < .05.