In recent years, attention has been drawn to the concept of IgG4-related diseases that was first proposed in Japan.
IgG4-related diseases are diseases of unknown etiology where, in addition to the presence of immune abnormalities and high IgG4 values in blood, the marked infiltration of lymphocytes and IgG4-positive plasma cells into organs and the resulting fibrosis are seen to cause synchronous or metachronous swelling and nodular or hypertrophic lesions.
A wide range of organs can be affected by IgG4-related diseases (refer to the Figure: Lesions in various organs from IgG4-related diseases), and present with differing organ-specific symptoms.
In addition, the lesions can often spread into multiple organs and present characteristics of a systemic disease, and sometimes there can be serious complications such as organ failure.
The measurement of serum IgG4 has been suggested to be an essential part of the comprehensive diagnostic criteria for IgG4-related diseases, and there are calls for it to be implemented on a wider scale.
*The Research Program for Intractable Disease Ministry of Health, Labour, and Welfare Japan Okazaki Group/Umehara Group.
Comprehensive Diagnostic Criteria for IgG4-related Diseases, 2011.
The Journal of the Japanese Society of Internal Medicine. 101(3): 797, 2012.
*From Comprehensive Diagnostic Criteria for IgG4-related Disease, 2011.
The Journal of the Japanese Society of internal Medicine. 101(3):801, 2012.
The Comprehensive Diagnostic Criteria for IgG4-related Disease, 2011, consist of three clinical criteria related to clinical findings, blood test result, and histopathological findings and were created with five basic concepts in mind.
*From Umehara H, Okazaki K, et al. Mod Rheumatol. 22:21-30. 2012
Comprehensive Diagnostic Criteria for lgG4-「elated Disease (lgG4-RD), 2011. The Journal of the」apanese Society of Internal Medicine. 101 (3): 802, 2012.
When clinical symptoms or organ enlargement clinically suggestive of IgG4-RD is observed, blood IgG4 should be measured and pathological examination performed whenever possible.
Even when IgG4-RD is only judged to be possible according to the comprehensive diagnostic criteria for IgG4-RD, it may be possible to reach a definitive diagnosis by also using organ-specific criteria.
As these criteria emphasize histopathology and do not recommend therapeutic diagnosis with steroids, they may not always have high diagnostic sensitivity for lesions in organs that are difficult to biopsy.
Therefore, it is recommended to also use organ-specific criteria for groups diagnosed with possible or probable lgG4-RD, and the diagnosis for different organs of the same patient can vary from definite to probable or possible.
The N-assay LA IgG4 Nittobo is a reagent to measure serum IgG4 by standard clinical analyzers.
By using this reagent, any laboratory equipped with clinical analyzers can measure serum IgG4, facilitating quicker and easier implementation of the test.
Excellent correlation with existing reagents up to 200 mg/dL
(Measured by JEOL BM6070-model clinical analyzer)
This reagent was designed to employ the method that does not display false low values even in regions of high IgG4 concentration
(Measured by Hitachi 7180-model clinical analyzer)
Uses monoclonal antibodies with high specificity for IgG4
|Theoretical value (mg/dL)||3000||3000||3000|
|value from N-assay LA IgG4 NIttobo (mg/dL)||10||12||4|
|Percentage of measurement value against theoretical value||0.33%||0.40%||0.13%|
Reference range for N-assay LA IgG4 Nittobo:11-121 mg/dL
(n = 471, in-house data)