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International Journal of Rheumatology
Volume 2012, Article ID 198314, 4 pages
http://dx.doi.org/10.1155/2012/198314
Review Article

The Utility of Serum IgG4 Concentrations as a Biomarker

1Center for Health, Safety, and Environmental Management, Shinshu University, 3-1-1 Asahi, Matsumoto 390-8621, Japan
2Department of Gastroenterology, School of Medicine Shinshu University, 3-1-1 Asahi, Matsumoto 390-8621, Japan
3Department of Medical Information, School of Medicine Shinshu University, 3-1-1 Asahi, Matsumoto 390-8621, Japan

Received 23 November 2011; Accepted 17 January 2012

Academic Editor: Yoh Zen

Copyright © 2012 Shigeyuki Kawa et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

IgG4-related disease is a new disease entity involving IgG4 in its clinical presentation and having 6 characteristic features: (1) systemic involvement; (2) solitary or multiple lesions showing diffuse or localized swelling, masses, nodules, and/or wall thickening on imaging; (3) high serum IgG4 concentration >135 mg/dL; (4) abundant infiltration of lymphoplasmacytes and IgG4-bearing plasma cells; (5) a positive response to corticosteroid therapy; and (6) complications of other IgG4-related diseases. To date, most IgG4-related diseases have been recognized as extrapancreatic lesions of autoimmune pancreatitis. This paper will discuss the utility of IgG4 as a biomarker of IgG4-related diseases, including in the diagnosis of autoimmune pancreatitis and its differentiation from pancreatic cancer, in the prediction of relapse, in the long-term follow-up of patients with autoimmune pancreatitis and normal or elevated IgG4 concentrations, and in patients with autoimmune pancreatitis and extrapancreatic lesions, as well as the role of IgG4 in the pathogenesis of IgG4-related disease.