High serum IgG4 concentrations in patients with sclerosing pancreatitis.

Background: Sclerosing pancreatitis is a unique form of pancreatitis that is characterized by irregular narrowing of the main pancreatic duct, lymphoplasmacytic inflammation of the pancreas, and hypergammaglobulinemia and that responds to glucocorticoid treatment. Preliminary studies suggested that serum IgG4 concentrations are elevated in this disease but not in other diseases of the pancreas or biliary tract. Methods: We measured serum IgG4 concentrations using single radial immunodiffusion and an enzyme-linked immunosorbent assay in 20 patients with sclerosing pancreatitis, 20 age- and sex-matched normal subjects, and 154 patients with pancreatic cancer, ordinary chronic pancreatitis, primary biliary cirrhosis, primary sclerosing cholangitis, or Sjogren's syndrome. Serum concentrations of immune complexes and the IgG4 subclass of immune complexes were determined by means of an enzyme-linked immunosorbent assay with monoclonal rheumatoid factor. Results: The median serum IgG4 concentration in the patients with sclerosing pancreatitis was 663 mg per deciliter (5th and 95th percentiles, 136 and 1150), as compared with 51 mg per deciliter (5th and 95th percentiles, 15 and 128) in normal subjects (P<0.001). The serum IgG4 concentrations in the other groups of patients were similar to those in the normal subjects. In patients with sclerosing pancreatitis, serum concentrations of immune complexes and the IgG4 subclass of immune complexes were significantly higher before glucocorticoid therapy than after four weeks of such therapy. Glucocorticoid therapy induced clinical remissions and significantly decreased serum concentrations of IgG4, immune complexes, and the IgG4 subclass of immune complexes. Conclusions: Patients with sclerosing pancreatitis have high serum IgG4 concentrations, providing a useful means of distinguishing this disorder from other diseases of the pancreas or biliary tract. (N Engl J Med 2001;344:732-8.) Copyright (C) 2001 Massachusetts Medical Society.