Department of Biochemistry and Immunology, Capital Institute of Pediatrics, 100020 Beijing, China.
Discov Med. 2023 Aug;35(177):476-482. doi: 10.24976/Discov.Med.202335177.48.
Elevated serum immunoglobulin G4 (IgG4) is one of the important features of patients with IgG4-related diseases (IgG4-RD). But diagnosing these diseases using IgG4 alone is tricky because the tests can sometimes give inaccurate results. Our research is focused on studying the ratio of IgG4 to two other substances, immunoglobulin G (IgG) and immunoglobulin G1 (IgG1), in the blood. We hope this approach will lead to more accurate diagnoses of IgG4-RD.
We conducted a study on 68 patients diagnosed with IgG4-related diseases (IgG4-RD) and 160 individuals suffering from other autoimmune diseases (AID) at our hospital between June 2018 and June 2022. Eighty healthy people who underwent physical examination in our hospital at the same time were randomly selected as controls, and medical records were collected for all subjects. The serum IgG and IgG subclasses were detected, and the IgG4/IgG and IgG4/IgG1 ratios were calculated.
We found that patients with IgG4-RD have significantly higher average levels of serum IgG4 and more elevated IgG4/IgG and IgG4/IgG1 ratios compared to individuals with other AID patients and those in good health ( < 0.001). The receiver operating characteristic (ROC) curve analysis showed that the diagnostic effectiveness area under the curve (AUC) of the serum IgG4/IgG ratio for IgG4-RD was 0.906 (95% confidence interval [CI], 0.865-0.947) and 0.921 (95% CI, 0.876-0.965) when comparing with other AID patients and healthy individuals, respectively. The optimal cut-off value for the IgG4/IgG ratio was 0.147 (with 72.1% sensitivity and 94.4% specificity) compared with AID patients and 0.129 (with 77.9% sensitivity and 96.2% specificity) compared with healthy individuals. Similarly, the AUC of the serum IgG4/IgG1 ratio for diagnosing IgG4-RD was 0.919 (95% CI, 0.882-0.956) and 0.916 (95% CI, 0.870-0.962) when compared with patients with other AID and healthy individuals, respectively. When we divided our study participants into a high IgG4/IgG ratio group (>0.129) and a normal IgG4/IgG ratio group (≤0.129) using a cut-off point of 0.129, we found through logistic regression analysis that those with a high IgG4/IgG ratio were more likely to be associated with IgG4-RD (odds ratio [OR], 31.25; 95% CI, 15.31-63.79; < 0.001). Likewise, a high IgG4/IgG1 ratio was also significantly linked to an increased risk of IgG4-RD (OR, 36.39; 95% CI, 17.57-75.38; < 0.001).
The serum's IgG4/IgG and IgG4/IgG1 ratios are independently linked to IgG4-RD and are valuable in its diagnosis.
血清免疫球蛋白 G4（IgG4）升高是 IgG4 相关疾病（IgG4-RD）患者的重要特征之一。但是，仅使用 IgG4 来诊断这些疾病很棘手，因为这些测试有时会给出不准确的结果。我们的研究集中在研究血液中 IgG4 与两种其他物质，免疫球蛋白 G（IgG）和免疫球蛋白 G1（IgG1）的比值。我们希望这种方法能更准确地诊断 IgG4-RD。
我们对 2018 年 6 月至 2022 年 6 月期间在我院诊断为 IgG4 相关疾病（IgG4-RD）的 68 例患者和 160 例患有其他自身免疫性疾病（AID）的个体进行了研究。同时在我院体检的 80 名健康人被随机选为对照组，并收集所有受试者的病历。检测血清 IgG 和 IgG 亚类，并计算 IgG4/IgG 和 IgG4/IgG1 比值。
我们发现，与其他 AID 患者和健康人相比，IgG4-RD 患者的血清 IgG4 平均水平显著升高，且 IgG4/IgG 和 IgG4/IgG1 比值更高（<0.001）。受试者工作特征（ROC）曲线分析显示，血清 IgG4/IgG 比值诊断 IgG4-RD 的曲线下面积（AUC）分别为 0.906（95%置信区间 [CI]，0.865-0.947）和 0.921（95% CI，0.876-0.965），与其他 AID 患者和健康人相比。IgG4/IgG 比值的最佳截断值为 0.147（敏感性为 72.1%，特异性为 94.4%），与 AID 患者相比；0.129（敏感性为 77.9%，特异性为 96.2%），与健康人相比。同样，血清 IgG4/IgG1 比值诊断 IgG4-RD 的 AUC 分别为 0.919（95% CI，0.882-0.956）和 0.916（95% CI，0.870-0.962），与其他 AID 患者和健康人相比。当我们使用 0.129 作为截断点将研究参与者分为 IgG4/IgG 比值较高组（>0.129）和 IgG4/IgG 比值正常组（≤0.129）时，我们通过逻辑回归分析发现，高 IgG4/IgG 比值更有可能与 IgG4-RD 相关（比值比[OR]，31.25；95%CI，15.31-63.79；<0.001）。同样，高 IgG4/IgG1 比值也与 IgG4-RD 的发生风险显著增加相关（OR，36.39；95%CI，17.57-75.38；<0.001）。
血清 IgG4/IgG 和 IgG4/IgG1 比值与 IgG4-RD 独立相关，对其诊断有价值。
