High serum IgG4 concentrations in patients with sclerosing pancreatitis.

Background: Sclerosing pancreatitis is a unique form of pancreatitis that i s characterized by irregular narrowing of the main pancreatic duct, lymphop lasmacytic inflammation of the pancreas, and hypergammaglobulinemia and tha t responds to glucocorticoid treatment. Preliminary studies suggested that serum IgG4 concentrations are elevated in this disease but not in other dis eases of the pancreas or biliary tract. Methods: We measured serum IgG4 concentrations using single radial immunodi ffusion and an enzyme-linked immunosorbent assay in 20 patients with sclero sing pancreatitis, 20 age- and sex-matched normal subjects, and 154 patient s with pancreatic cancer, ordinary chronic pancreatitis, primary biliary ci rrhosis, primary sclerosing cholangitis, or Sjogren's syndrome. Serum conce ntrations of immune complexes and the IgG4 subclass of immune complexes wer e determined by means of an enzyme-linked immunosorbent assay with monoclon al rheumatoid factor. Results: The median serum IgG4 concentration in the patients with sclerosin g 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 a nd 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 p atients with sclerosing pancreatitis, serum concentrations of immune comple xes and the IgG4 subclass of immune complexes were significantly higher bef ore glucocorticoid therapy than after four weeks of such therapy. Glucocort icoid 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 con centrations, 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.