Innate immune responses to adenoviral vector-mediated acute pancreatitis.

Objectives: The role of innate immunity in the development of acute viral pancreatitis is not well understood. The aim of the study was to characterize the role of the innate immune system, especially macrophages, natural killer (NK), and NK T (NKT) cells, in the generation of immune responses to intrapancreatic delivery of recombinant adenoviral vector.

Methods: Adenoviral vectors expressing beta-galactosidase or green fluorescent protein genes with viral capsid conjugated covalently with carbocyanine dye were directly injected into the pancreas of C57Bl/6 mice.

Results: Fluorescent microscopy of the pancreas showed that 30 minutes after vector administration, adenoviral particles localized to cell membranes, internalized, and localized to the nucleus by 4 hours, and transgene expression began at 24 hours. Immunohistochemical staining showed macrophages entering the pancreas shortly after vector administration, with maximal infiltration at day 4, and then disappearing as antigen-expressing cells were eliminated. Intrapancreatic macrophages appeared to deliver viral capsid proteins to the spleen. Flow cytometry showed that NK and NKT cells migrate to the pancreas and persist. Serum cytokines IL-6, IL-10, and IL-12 were all elevated.

Conclusion: Macrophages and NK and NKT cells play a major role in the development of acute adenovirus-mediated pancreatitis.