Objective To investigate the prognostic value of CD 4+CD25+/high CD127 low/-and CD14+HLA-DRlow/-for evaluating the severity of acute pancreatitis .Methods The percentages of CD4+CD25+/highCD127low/-and CD14+HLA-DRlow/-and the CD64 index were measured by flow cytometry in pa-tients with acute pancreatitis ( including 43 cases of mild acute pancreatitis and 24 cases of severe acute pan-creatitis).Moreover, the levels of C-reactive protein (CRP), acute physiology and chronic health evaluationⅡ( APACHEⅡ) score and CT severity index ( CTSI ) were detected for a correlation analysis .Results The percentages of CD4+CD25+/highCD127low/-and CD14+HLA-DRlow/-and the CD64 index in patients with severe and mild acute pancreatitis were significantly higher than those in healthy subjects .Patients with se-vere acute pancreatitis showed higher percentages of CD 14+HLA-DRlow/-than patients with mild acute pan-creatitis.With the disease progression, the CD64 index and the levels of CD4+CD25+/highCD127low/-, CD14+HLA-DRlow/-and CRP were significantly dropped after an initial increase in patients with mild acute pancrea -titis, while these indexes were continuously elevated in patients with severe acute pancreatitis .The percent-age of CD14+HLA-DRlow/-was positively correlated with CD64 index, CRP level, APACHEⅡ score and CTSI.Conclusion CD14+HLA-DRlow/-level was closely related to the severity of acute pancreatitis , which could be used as immune parameter for the estimation of the clinical severity of acute pancreatitis .