Objectives. This study was conducted to clarify whether or not Tregs are involved in the development of immune-mediated
pancreatitis in MRL/Mp mice as an AIP (
autoimmune pancreatitis) model, in order to understand more clearly the pathogenic mechanism of AIP. Methods. We compared the immunohistochemical features of pancreatic forkhead box P3 (Foxp3) in the administration of
poly I:C in MRL/Mp mice and two types of control mice (BALB/c and C57BL/6). As a contrast, we analyzed three mouse models of
pancreatitis without autoimmune mechanism (
Cerulein-,
Ligation-, and
Ligation +
Cerulein-treated mice). After staining these specimens, we compared the ratios of Foxp3-positive cells to infiltrated mononuclear cells (Foxp3/Mono). Results. Our immunohistochemical study of Foxp3 revealed that the infiltration of Foxp3-positive cells increased in
poly I:C-treated MRL/Mp mice. The histopathological score of
pancreatitis showed no difference among
poly I:C-treated MRL/Mp,
Ligation-, and
Ligation +
Cerulein-treated mice; however, the Foxp3/Mono ratio in
poly I:C-treated MRL/Mp mice was significantly increased compared with
Ligation- and
Ligation +
Cerulein-treated mice. Conclusions. MRL/Mp mice treated with
poly I:C showed early development of
pancreatitis with abundant infiltration of Foxp3-positive cells. There may be a possibility that Tregs are involved in the development of
pancreatitis in these mice.