Infected pancreatic necrosis and its related septic complications are the major cause of death in patients with acute pancreatitis, therefore prevention of pancreatic infection is of great clinical value in the treatment of AP. Immunosuppression and disorders characterized by decreased HLA-DR expression and unbalanced CD3/CD4+/CD8+ T cells of PBMC are thought to be associated with the development of pancreatic infection. Thymosin alpha 1 has been shown to have immunomodulatory properties and its effects in preventing pancreatic infection was not well studied. To evaluate the effects of TA1 use in the early phase on preventing pancreatic infection, immunomodulation and clinical outcomes in patients with AP,we aimed to design this study.

Study Background \& Rationale: Infected pancreatic necrosis and its related septic complications are the major cause of death in patients with acute pancreatitis1, therefore prevention of pancreatic infection is of great clinical value in the treatment of AP. Immunosuppression and disorders characterized by decreased HLA-DR expression and unbalanced CD3/CD4+/CD8+ T cells of PBMC are thought to be associated with the development of pancreatic infection2, 3. Thymosin alpha 1 has been shown to have immunomodulatory properties and its effects in preventing pancreatic infection was not well studied4. Aim of This Study: To evaluate the effects of TA1 use in the early phase on preventing pancreatic infection, immunomodulation and clinical outcomes in patients with AP. Sample Size Estimation: The prevalence of pancreatic infection was reported to be around 25% in AP episodes. To demonstrate a 40% reduction in the prevalence of pancreatic infection with 80% power at a two-sided alpha level of .05, we projected an estimated sample size of 500 participants. Considering possible 2% withdraw, we plan to randomize 510 patients in total.