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. 2021 Aug;35(8):e23874.
doi: 10.1002/jcla.23874. Epub 2021 Jun 14.

Establishment of time-resolved fluoroimmunoassay of IgG4 based on magnetic microspheres

Qingqing Wu  1 , Chen Hang  2 , Ting Li  1 , Binrong Wang  1 , Yuan Qin  1 , Yigang Wang  1 , Xiumei Zhou  1 , Pengguo Xia  1   3 , Huiming Sheng  2 , Pei Huang  4 , Biao Huang  1
Affiliations

Establishment of time-resolved fluoroimmunoassay of IgG4 based on magnetic microspheres

Qingqing Wu et al. J Clin Lab Anal. 2021 Aug.

Abstract

Background: The abnormal increase in serum IgG4 level is an important clinical symptom of IgG4-related disease (IgG4-RD), and the detection of serum IgG4 level is a powerful tool for the diagnosis of IgG4-RD. This study was conducted to establish a simple and rapid immunoassay for the determination of human serum IgG4 levels.

Methods: Based on the competition method, a novel immunoassay was established for the determination of human serum IgG4 using a combination of time-resolved fluoroimmunoassay (TRFIA) and magnetic microspheres. IgG4 was coupled with magnetic microspheres and competed with IgG4 in the samples to bind the Eu3+ -labeled anti-IgG4 antibody. The immunocomplex was separated and washed in a magnetic field, and the fluorescence counts were measured according to the number of dissociated europium ions.

Results: The analytical sensitivity of IgG4-TRFIA based on magnetic microspheres was 0.006 g/L, and the detection range was 0.006-20 g/L under optimal conditions. The precision, recovery, and specificity of this immunoassay were demonstrated to be acceptable. The clinical application of IgG4-TRFIA based on magnetic microspheres was evaluated and compared with that of immunonephelometry. The results showed that the two detection methods had a good correlation, with a correlation coefficient of .9871.

Conclusion: IgG4-TRFIA based on magnetic microspheres has the advantages of high sensitivity, wide detection range, and short analysis time and has the potential to become a useful tool for the diagnosis of IgG4-RD.

Keywords: IgG4; IgG4-RD; immunoassay; magnetic microspheres; time-resolved fluorescence immunoassay.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

FIGURE 1
FIGURE 1
Schematic diagram of IgG4‐TRFIA based on magnetic microspheres
FIGURE 2
FIGURE 2
Optimization of the concentration of IgG4‐coated magnetic microspheres
FIGURE 3
FIGURE 3
Optimization of the concentration of Eu3+‐anti‐IgG4 antibody
FIGURE 4
FIGURE 4
Standard curve of IgG4‐TRFIA
FIGURE 5
FIGURE 5
Comparison between the established method and immunonephelometry method
See this image and copyright information in PMC

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