PDCD1 and autoimmune thrombocytopenic purpura: miR-155-5p was upregulated and SOCS1 down regulated in PBMCs and macrophages from ITP.Inhibition of miR-155-5p or upregulation of SOCS1 facilitated the M2 polarization, increased M2/M1 ratio. Silencing SOCS1 blocks PD1/PDL1 pathway and upregulates miR-155-5p.