title: Detection of serum IgG4 levels in patients with IgG4-related disease and other disorders.
abstract: OBJECTIVE
  Elevated serum IgG4 levels are an important hallmark for diagnosing IgG4-related disease (IgG4-RD), but can also be observed in other diseases. This study aimed to compare two different testing methods for IgG4: ELISA and nephelometric assay. Both assays were used to measure serum IgG4 concentrations, and to assess the prevalence of high serum IgG4 levels in both IgG4-RD and non-IgG4-RD diseases.
  
  
  METHODS
  A total of 80 serum samples were tested using the nephelometric assay and ELISA method that we established. Serum IgG4 concentrations were determined by ELISA for 957 patients with distinct diseases, including 12 cases of IgG4-RD and 945 cases of non-IgG4-RD.
  
  
  RESULTS
  IgG4 levels from 80 selected serum samples examined by ELISA were in agreement with those detected using the nephelometry assay. Meanwhile, the serum IgG4 concentrations measured by ELISA were also consistent with the clinical diagnoses of patients with IgG4-RD during the course of disease. The Elevated levels of serum IgG4 (>1.35 g/L) were detected in all IgG4-RD (12/12) patients, and the prevalence of high IgG4 serum levels was 3.39% in non-IgG4-RD cases. Among them, the positive rates of serum IgG4 were 2.06% in patients with carcinoma and 6.3% in patients with other non-IgG4 autoimmune diseases.
  
  
  CONCLUSIONS
  Our established ELISA method is a reliable and convenient technique, which could be extensively used in the clinic to measure serum IgG4 levels. High levels of IgG4 were observed in IgG4-RD. However, this phenomenon could also be observed in other diseases, such as carcinomas and other autoimmune diseases. Thus, a diagnosis of IgG4 disease cannot only be dependent on the detection of elevated serum IgG4 levels.
authors.affiliation: Department of Rheumatology and Immunology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Yuying
authors.initials: Y
authors.lastname: Su
authors.affiliation: Department of Stomatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Sun
authors.affiliation: Department of Rheumatology and Immunology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Chenqiong
authors.initials: C
authors.lastname: Wang
authors.affiliation: Department of Rheumatology and Immunology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Xuefen
authors.initials: X
authors.lastname: Wu
authors.affiliation: Department of Rheumatology and Immunology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Ye
authors.initials: Y
authors.lastname: Miao
authors.affiliation: Department of Rheumatology and Immunology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Xiong
authors.affiliation: Department of Rheumatology and Immunology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Bai
authors.affiliation: Department of Rheumatology and Immunology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Lingli
authors.initials: L
authors.lastname: Dong
mesh_terms: D001327:Autoimmune Diseases / Q000097:blood; D002277:Carcinoma / Q000097:blood; D002318:Cardiovascular Diseases / Q000097:blood; D004066:Digestive System Diseases / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005260:Female; D005355:Fibrosis; D005831:Genital Diseases, Female / Q000097:blood; D006402:Hematologic Diseases / Q000097:blood; D006801:Humans; D006942:Hypergammaglobulinemia / Q000097:blood* / Q000175:diagnosis / Q000209:etiology / Q000473:pathology; D007074:Immunoglobulin G / Q000097:blood*; D007239:Infections / Q000097:blood; D007674:Kidney Diseases / Q000097:blood; D008297:Male; D009369:Neoplasms / Q000097:blood; D009391:Nephelometry and Turbidimetry; D009422:Nervous System Diseases / Q000097:blood; D010689:Phlebitis / Q000097:blood / Q000209:etiology / Q000276:immunology; D010950:Plasma Cells / Q000276:immunology / Q000473:pathology; D012120:Respiration Disorders / Q000097:blood
chemical_list: D007074:Immunoglobulin G