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International Journal of Rheumatology
Volume 2012, Article ID 580814, 5 pages
http://dx.doi.org/10.1155/2012/580814
Clinical Study

Cutoff Values of Serum IgG4 and Histopathological IgG4+ Plasma Cells for Diagnosis of Patients with IgG4-Related Disease

1Hematology and Immunology, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Kahoku-gun, Ishikawa 920-0293, Japan
2Department of Pathology and Laboratory Medicine, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Kahoku-gun, Ishikawa 920-0293, Japan
3First Department of Internal Medicine, School of Medicine, Sapporo Medical University, S1 W17 Chuo-ku, Sapporo, Hokkaido 060-8556, Japan
4Department of Internal Medicine, Nagaoka Red Cross Hospital, Sensyu-2 297-1, Nagaoka-shi, Niigata 940-2085, Japan
5Ophthalmology Department, Kobe Kaisei Hospital, Shinohara Kitamachi 3-11-15, Nada Ku, Kobe City, Hyogo 657-0068, Japan
6Department of Japanese Oriental Medicine, University of Toyama, 2630 Sugitani, Toyama city, Toyama 930-0194, Japan
7First Department of Internal Medicine, University of Toyama, 2630 Sugitani, Toyama city, Toyama 930-0194, Japan
8Nagasaki Graduate School of Health Sciences, 1-7-1 Sakamoto, Nagasaki city, Nagasaki 852-8501, Japan
9Rheumatic Disease Center, Kurashiki Medical Center, 250 Bakuro-chou, Kurashiki, Okayama 710-8522, Japan
10Division of Rheumatology, Department of Internal Medicine, Kanazawa University, 13-1 Takara-machi, Kanazawa, Ishikawa 920-8641, Japan
11Hiroshima Bay Clinic, 2-2-19 Yanoshin-machi, Aki-ku, Hiroshima city, Hiroshima 736-0084, Japan
12Department of Internal Medicine, Isahaya General Hospital, 24-1 Eishohigasi-macki, Isahaya, Nagasaki 854-8501, Japan
13Sugiura Clinic, 2-8-3 Imaichi-chou, Kitashin-machi, Izumo, Shimane 693-0002, Japan
14Department of Rheumatology, University of Tsukuba, 2-1-1 Amakubo, Tsukuba, Ibaraki 305-8576, Japan

Received 1 December 2011; Revised 29 February 2012; Accepted 29 February 2012

Academic Editor: John H. Stone

Copyright © 2012 Yasufumi Masaki 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 classification established in Japan in the 21st century. Patients with IgG4-related disease display hyper-IgG4-gammaglobulinemia, massive infiltration of IgG4+ plasma cells into tissue, and good response to glucocorticoids. Since IgG4 overexpression is also observed in other disorders, it is necessary to diagnose IgG4-related disease carefully and correctly. We therefore sought to determine cutoff values for serum IgG4 and IgG4/IgG and for IgG4+/IgG+ plasma cells in tissue diagnostic of IgG4-related disease. Patients and Methods. We retrospectively analyzed serum IgG4 concentrations and IgG4/IgG ratio and IgG4+/IgG+ plasma cell ratio in tissues of 132 patients with IgG4-related disease and 48 patients with other disorders. Result. Serum IgG4 >135  mg/dl demonstrated a sensitivity of 97.0% and a specificity of 79.6% in diagnosing IgG4-related disease, and serum IgG4/IgG ratios >8% had a sensitivity and specificity of 95.5% and 87.5%, respectively. IgG4+cell/IgG+ cell ratio in tissues >40% had a sensitivity and specificity of 94.4% and 85.7%, respectively. However, the number of IgG4+ cells was reduced in severely fibrotic parts of tissues. Conclusion. Although a recent unanimous consensus of all relevant researchers in Japan recently established the diagnostic criteria for IgG4-related disease, findings such as ours indicate that further discussion is needed.