Serum Immunoglobulin G Fraction 4 Levels in Pancreatic Cancer : Elevations Not Associated With Autoimmune Pancreatitis

Abstract Context.—Autoimmune pancreatitis is an uncommon, inflammatory disease of the pancreas that presents with clinical features, such as painless jaundice and a pancreatic mass, similar to those caused by pancreatic cancer. Patients with autoimmune pancreatitis frequently have elevated serum immunoglobulin G fraction 4 (IgG4) levels, and their pancreatic tissue may show IgG4-positive plasma cell infiltration. It is imperative to differentiate autoimmune pancreatitis from pancreatic cancer because autoimmune pancreatitis typically responds to corticosteroid treatment. A previous Japanese study reported that serum IgG4 greater than 135 mg/dL was 97% specific and 95% sensitive in predicting autoimmune pancreatitis. Objective.—To prospectively measure serum IgG4 levels in pancreatic cancer patients to ascertain whether increased levels might be present in this North American population. Design.—We collected blood samples and phenotypic information on 71 consecutive pancreatic cancer patients and 103 healt...