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Clinical Characteristics of Patients With IgG4-Related Disease Complicated by Hypocomplementemia

Yuya Fujita1,2, Shoichi Fukui1, Masataka Umeda1

  • 1Department of Immunology and Rheumatology, Division of Advanced Preventive Medical Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.

Frontiers in Immunology
|March 17, 2022
PubMed

Insights

Patients with immunoglobulin G (IgG) 4-related disease (IgG4-RD) and hypocomplementemia show a more active disease phenotype. Hypocomplementemia is linked to increased organ involvement and higher relapse rates in IgG4-RD.

Area of Science:

  • Immunology
  • Rheumatology
  • Nephrology

Background:

  • Immunoglobulin G (IgG) 4-related disease (IgG4-RD) is a fibroinflammatory condition.
  • A subset of IgG4-RD patients exhibit hypocomplementemia, characterized by low C3 and/or C4 levels.
  • The clinical significance of hypocomplementemia in IgG4-RD remains to be fully elucidated.

Purpose of the Study:

  • To identify the clinical characteristics of IgG4-RD patients with hypocomplementemia.
  • To investigate the association between hypocomplementemia and disease activity, serological markers, and relapse rates in IgG4-RD.

Main Methods:

  • Retrospective analysis of demographic, clinical, and laboratory data from 85 IgG4-RD patients.
  • Definition of hypocomplementemia: serum C3 and/or C4 levels below the lower limit of normal at diagnosis.
  • Comparison of characteristics between patients with and without hypocomplementemia, including organ involvement, serological markers, and relapse frequency.

Main Results:

  • 38% of IgG4-RD patients presented with hypocomplementemia at diagnosis.
  • Hypocomplementemic patients showed significantly higher rates of lymph node, lung, and kidney involvement.
  • Hypocomplementemia was associated with elevated IgG, IgG4, soluble interleukin 2-receptor (sIL-2R) levels, and increased disease activity and relapse frequency.

Conclusions:

  • Hypocomplementemia in IgG4-RD is associated with a more active and aggressive clinical phenotype.
  • The complement system likely plays a role in the pathophysiology of IgG4-RD.
  • Hypocomplementemia may serve as a predictive marker for relapse in IgG4-RD patients.
Abstract

Keywords:
IgGIgG4IgG4-RDcomplement C3complement C4

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