Blood samples were collected from the Chinese People's Liberation Army General Hospital. The investigators collected samples in emergency intensive care unit (EICU), surgical intensive care unit (SICU) and respiratory intensive care unit (RICU) between July 2014 to March 2015. Septic patients were divided into sepsis, severe sepsis and septic shock according to the diagnostic criteria. Peripheral white blood cells were sorted into monocytes, lymphocytes and neutrophils by using flow cytometry (Flow Cytometry, FCM). Jurkat T cell lines were purchased from Chinese Academy of Medical Sciences Institute of basic medical sciences. miRNAs agomirs and antagonists were used to establish miR-223, miR-15a, miR-16 overexpression and knock-out transient transfection cell lines. Western blot was used to detect difference expression of protein expression.