Regulatory T Cells in Type 1 Autoimmune Pancreatitis

Abstract EN

Autoimmune pancreatitis (AIP) is a newly recognized pancreatic disorder.

Recently, International Consensus Diagnostic Criteria for AIP (ICDC) was published.

In this ICDC, AIP was classified into Type 1 and Type 2.

Patients with Type 1 AIP have several immunologic and histologic abnormalities specific to the disease, including increased levels of serum IgG4 and storiform fibrosis with infiltration of lymphocytes and IgG4-positive plasmacytes in the involved organs.

Among the involved organs showing extrapancreatic lesions, the bile duct is the most common, exhibiting sclerosing cholangitis (IgG4-SC).

However, the role of IgG4 is unclear.

Recently, it has been reported that regulatory T cells (Tregs) are involved in both the development of various autoimmune diseases and the shift of B cells toward IgG4, producing plasmacytes.

Our study showed that Tregs were increased in the pancreas with Type 1 AIP and IgG4-SC compared with control.

In the patients with Type 1 AIP and IgG4-SC, the numbers of infiltrated Tregs were significantly positively correlated with IgG4-positive plasma cells.

In Type 1 AIP, inducible costimulatory molecule (ICOS)+ and IL-10+ Tregs significantly increased compared with control groups.

Our data suggest that increased quantities of ICOS+ Tregs may influence IgG4 production via IL-10 in Type 1 AIP.