Total RNA isolation 5 ml of peripheral blood samples anti-coagulated with EDTA were drawn from patients suspected with PE immediately after admitting to the hospital and from those patients without PE, respectively. Mononuclear cells were obtained through density gradient centrifugation with Ficoll solution and remaining red blood cells were destroyed with erythrocyte lysis buffer (Qiagen, Hilden, Germany). Total mononuclear cell RNA was extracted with TRIzol(Invitrogen, Carlsbad, USA) and purified with Qiagen RNeasy column (Qiagen, Hilden, Germany) according to the manufacturer's instructions. Isolated total RNA was testified and quantified by means of Nanodrop ND-1000 spectrophotometer (Nanodrop Technology, Cambrige, UK).