Intriguingly, the PD-1 expression on CD8+ T cells was associated with the platelet counts in active ITP mice after decitabine therapy, suggesting that the effect of low-dose decitabine in ameliorating thrombocytopenia in ITP might be related to the increasing PD-1 expression on CD8+ T cells. This evidence concerns the gene PDCD1 and autoimmune thrombocytopenic purpura.