Are pancreatic autoantibodies associated with azathioprine-induced pancreatitis in Crohn's disease?

CONTEXT Azathioprine is frequently used in the treatment of Crohn's disease. A severe side effect is acute pancreatitis, which is specific for Crohn's disease. Autoantibodies against exocrine pancreas occur in about 30% of Crohn's disease cases but not in other inflammatory diseases. Pancreatic autoantibody positive Crohn's disease patients might have a low grade inflammation of the pancreas which may be aggravated by the introduction of azathioprine, resulting in clinically overt acute pancreatitis. OBJECTIVE We hypothesized that the presence of pancreatic autoantibodies in Crohn's disease patients is associated with the development of azathioprine-induced pancreatitis. PARTICIPANTS Eight patients with Crohn's disease and azathioprine-induced pancreatitis and 26 patients with Crohn's disease not using azathioprine. MAIN OUTCOME MEASURE Pancreatic autoantibodies were determined by a standardized immunofluorescence method. RESULTS Two out of 8 patients with azathioprine-induced pancreatitis were positive for pancreatic autoantibodies (25.0%), detectable in serum dilutions of 1:40 and 1:160, respectively. In the control group of Crohn's disease patients, two (7.7%) were positive in serum dilutions of 1:2. All positive samples had an extracellular fluorescence pattern. The difference in the prevalence of pancreatic autoantibodies was not statistically significant (P=0.229). CONCLUSIONS We could not confirm our hypothesis that most or all patients with azathioprine-induced pancreatitis were pancreatic autoantibody positive. The prevalence of pancreatic autoantibodies in the Crohn's disease patients in our group was lower than in previous reports.This study does not support an association between pancreatic autoantibodies and azathioprine-induced pancreatitis in Crohn's disease. However, this association should not be definitively excluded and larger, preferably prospective, studies are needed.