In this study, our results indicated that the expression levels of OX40 and OX40L mRNA in PBMCs from ITP patients were significantly increased compared to those in PBMCs from the HCs, and the expression levels of OX40 and OX40L mRNA were notably different between ITP patients with positive and negative antiplatelet autoantibodies. This evidence concerns the gene TNFSF4 and autoimmune thrombocytopenic purpura.