Sepsis is a systemic inflammatory reaction caused by infection, trauma, etc. In the process of sepsis, the apoptosis of lymphocyte serves as a vital factor of immune dysfunction. Micro-RNAs (miRNAs) are endogenous small non-coding RNA molecules. Our previous studies have showed the diagnostic and prognostic value of a series circulant miRNAs in human serum in sepsis. The present research further study the regulatory mechanism of those miRNAs in lymphocyte in sepsis. Our research is based on the clinical value of miR-223, miR-15a, miR-16. The investigators discuss the potential role of miR-223, miR-15a, miR-16 in regulating the proliferation and apoptosis of lymphocyte in sepsis and aim to find new targets for sepsis treatment.