Comparison of neutrophil infiltration between type 1 and type 2 autoimmune pancreatitis.

ABSTRACT

BACKGROUND: Characteristics of type 2 autoimmune pancreatitis (AIP) is granulocyte epithelial lesions, called idiopathic duct-centric pancreatitis (IDCP). To clarify pathogenesis of IDCP, we investigated mechanism of neutrophil infiltration in type 1 AIP, called lymphoplasmacytic sclerosing pancreatitis (LPSP) and IDCP. METHOD: This study was performed on resected pancreata from patients with alcoholic chronic pancreatitis (ACP, n = 10), LPSP (n = 10) and IDCP (n = 12). The number of neutrophils around the pancreatic ducts was counted. The expression of neutrophils chemoattractants granulocyte chemotactic protein-2 (GCP-2) and interleukin-8 (IL-8) in the pancreatic duct epithelia was examined using immunohistochemistry. The cell staining intensity is scored as negative (0), weak (1), moderate (2) or strong (3). RESULTS: The median number of neutrophils around the interlobular pancreatic ducts was significantly higher in IDCP (15.16; interquartile range [IQR] 9.74-18.41) than in ACP (2.66; IQR 1.33-4.33) (P < 0.05) and LPSP (3.16; IQR 2.74-4.57) (P < 0.01). There was no significant difference in the median number of neutrophils around the intralobular pancreatic ducts among ACP (1.16; IQR 0.33-3.41), LPSP (3.16; IQR 0.74-5.5) and IDCP (3.00; IQR 1.08-7.91). The median score of GCP-2 in the interlobular pancreatic duct epithelia was significantly higher in IDCP (1.5; IQR 0.25-2) than in ACP (0; IQR 0-0.75) (P < 0.05) and LPSP (0; IQR 0-0.75) (P < 0.05). There was no significant difference in the median score of IL-8 in the interlobular pancreatic duct epithelia among ACP (0; IQR 0-0.75), LPSP (1; IQR 0-1.75) and IDCP (0.5; IQR 0-1). CONCLUSIONS: Significantly increased neutrophil infiltration around the interlobular pancreatic duct in IDCP may depend on GCP-2.