Detection of Polyclonal Increases in Immunoglobulin G4 Subclass by Distinct Patterns on Capillary Serum Protein Electrophoresis: Diagnostic Pitfalls and Clinical Observations in a Study of 303 Cases.

毛细血管血清蛋白电泳法对免疫球蛋白G4多克隆性升高进行再分类：303例研究的诊断误区及临床观察

Finn WG,Gulbranson R,Fisher S,Rae Sample L,Shalhoub R,Hedstrom D,Keren DF

阅读：958 American Journal of Clinical Pathology； Volume 146, Issue 3,September 2016:303-11

Abstract

Autoimmunity, hypersensitivity, and the recently recognized set of syndromes collectively termed immunoglobulin G4-related disease (IgG4-RD) may be associated with increased serum IgG4 levels. We reviewed our experience detecting increased IgG4 by distinct serum protein electrophoresis (SPEP) patterns.
We studied 303 capillary SPEP cases with dome-like anodal γ changes and increased measured serum IgG4.
IgG4 ranged from 208 to 6,670 mg/dL (normal, <201 mg/dL). Seventeen of 91 cases evaluated by immunosubtraction appeared monotypic (16 κ, 1 λ), but all five cases further analyzed by isoelectric focusing appeared polyclonal. Six cases with markedly increased IgG4 had presumptive evidence of IgG4-RD. Sixteen of 45 assessed patients had autoantibodies.
Increased polyclonal IgG4 has a characteristic SPEP pattern that may mimic monoclonal gammopathy, even on immunosubtraction. κ Pseudo-restriction might reflect the naturally high κ/λ ratio of the IgG4 subclass. Autoantibodies were common, and the greatest IgG4 increases had clinical features of IgG4-RD.

摘要

自身免疫、高敏感性以及近来才认识到的一组被命名为免疫球蛋白G4相关疾病（IgG4-RD）的综合征都可能与血清G4水平增高相关。我们对血清蛋白电泳（SPEP）检测中IgG4升高时的不同表现相关经验进行了总结。

我们针对303例样本采用毛细血管SPEP法进行实验，用类似于r阳极的方法检测血清中IgG4的含量改变和增加，结果提示IgG4的含量在208到6670mg/dL之间变动（参考值<201mg/dL）。在91例样本中有17例通过免疫碱法求值后表现为单型（16 κ, 1 λ）；然而对5例样本进行更深入的分析，等电点聚焦为多克隆；6例IgG4含量显著增加者具有推定为IgG4相关疾病的依据；45例评估患者中有16例存在自身抗体。

IgG4多克隆含量的增加具有特征性的SPEP表现，且在免疫碱法中也有相同表现，可类似单克隆免疫球蛋白增生性疾病。k伪限制性可能反映了IgG4亚群中k/λ比值较高的自然属性。IgG4相关疾病的临床特征中本就常见自身抗体，且IgG4的增加最为显著。