title: Decreased production of immunoglobulin M and A in autoimmune pancreatitis.
abstract: BACKGROUND
  Autoimmune pancreatitis (AIP) is a rare type of chronic pancreatitis caused by an autoimmune abnormality. It is well known that high serum concentrations of IgG4 are helpful for making a diagnosis of AIP; however, it is unclear whether there are abnormalities in the production of other immunoglobulins in AIP.
  
  
  METHODS
  We examined the immune condition of AIP patients before and after glucocorticoid treatment, focusing on serum levels of IgG, IgG4, IgM and IgA, and compared the results with those in other hepato-pancreatic diseases, such as autoimmune hepatitis, primary biliary cirrhosis, chronic pancreatitis and pancreatic carcinoma.
  
  
  RESULTS
  IgM and IgA were decreased in patients with untreated AIP. IgM and IgG or IgG4 were negatively correlated in patients with AIP. The ratios of IgG to IgM and IgG to IgA in patients with AIP were significantly increased compared with the other diseases. The diagnostic sensitivity of IgG to IgM and IgG to IgA was 0.800 and 0.950, and the specificity of each ratio was 0.703 and 0.728, respectively, in the differentiation of AIP from the other diseases. IgM was not significantly changed after glucocorticoid treatment in the patients with AIP, while IgG, IgG4 and IgA decreased.
  
  
  CONCLUSIONS
  The ratios of IgG to IgM and IgG to IgA may serve as novel diagnostic markers to differentiate AIP from other hepato-pancreatic diseases. Furthermore, low concentrations of IgM and IgA may be involved in the pathogenesis of AIP.
authors.affiliation: Third Department of Internal Medicine, University of Occupational and Environmental Health, Japan School of Medicine, Yahatanishi-ku, Kitakyushu, Japan. tagu@med.uoeh-u.ac.jp
authors.forename: Masashi
authors.initials: M
authors.lastname: Taguchi
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Kihara
authors.forename: Yoshikuni
authors.initials: Y
authors.lastname: Nagashio
authors.forename: Mitsuyoshi
authors.initials: M
authors.lastname: Yamamoto
authors.forename: Makoto
authors.initials: M
authors.lastname: Otsuki
authors.forename: Masaru
authors.initials: M
authors.lastname: Harada
mesh_terms: D000368:Aged; D001327:Autoimmune Diseases / Q000175:diagnosis / Q000188:drug therapy / Q000276:immunology*; D005260:Female; D005938:Glucocorticoids / Q000627:therapeutic use; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood* / Q000187:drug effects; D007074:Immunoglobulin G / Q000097:blood / Q000187:drug effects; D007075:Immunoglobulin M / Q000097:blood* / Q000187:drug effects; D008107:Liver Diseases / Q000276:immunology; D008297:Male; D008875:Middle Aged; D010182:Pancreatic Diseases / Q000276:immunology; D050500:Pancreatitis, Chronic / Q000175:diagnosis / Q000188:drug therapy / Q000276:immunology*; D012680:Sensitivity and Specificity
chemical_list: D005938:Glucocorticoids; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M