Backgrounds & Aims: Neutrophil infiltration and acinar cell death are two key pathologic events of acute pancreatitis, which are interrelated. We previously showed that neutrophils limit apoptosis and increase severity of experimental pancreatitis, however, underlying mechanisms remain unknown. This study was designed to determine the signaling mechanisms mediating regulation of cell death in pancreatitis by neutrophils. Methods: Cerulein pancreatitis was induced in rats injected with anti-PMN (neutrophil count 23 ± 7/μL) or control serum (701 ± 133 μL). Results: In pancreatitis from neutrophil-depleted (ND) rats, activity of executioner caspase-3 was elevated, whereas sensitivity of mitochondria to Ca 2+-induced cytochrome c release and mitochondrial depolarization were same. These data indicate that increased apoptosis was not mediated through direct effect of neutrophil-derived mediators on mitochondrial function. Neutrophil depletion greatly increased protein level and activity of caspase-2 in cerulein pancreatitis whereas neither levels nor activities of caspases-9 and -8 were affected. P53, a known activator of caspase -2, was upregulated in ND rats subjected to pancreatitis. Furthermore, caspase -2 activation in acinar cells was prevented by p53 inhibitor, pifithrin. Conclusion: Thus, ND increase apoptosis in cerulein pancreatitis through upregulation of p53 leading to caspase-2 activation. The data suggest upregulation of p53 as a potential strategy to stimulate apoptosis and decrease severity of acute pancreatitis.