However, emerging evidence suggests that the reported increase in IgG4 levels detected after repeated vaccination with the mRNA vaccines may not be a protective mechanism; rather, it constitutes an immune tolerance mechanism to the spike protein that could promote unopposed SARS-CoV2 infection and replication by suppressing natural antiviral responses. Increased IgG4 synthesis due to repeated mRNA vaccination with high antigen concentrations may also cause autoimmune diseases, and promote cancer growth and autoimmune myocarditis in susceptible individuals.

然而，新出現的證據表明，重複接種 mRNA 疫苗後檢測到的 IgG4 水平升高可能不是一種保護機制；相當，它構成了對刺突蛋白的免疫耐受機制，可以通過抑制自然抗病毒反應來促進不受對抗的 SARS-CoV2 感染和複製。由於反覆進行高抗原濃度的 mRNA 疫苗接種，導致 IgG4 合成增加，也可能引起自身免疫性疾病，並促進易感個體的癌症生長和自身免疫性心肌炎。

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10222767/#:~:text=However%2C%20emerging%20evidence%20suggests%20that,CoV2%20infection%20and%20replication%20by

IgG4, the least represented human IgG subclass in serum, is an intriguing antibody with unique biological properties, such as the ability to undergo Fab-arm exchange and limit immune complex formation. The lack of effector functions, such as antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity, is desirable for therapeutic purposes. IgG4 plays a protective role in allergy by acting as a blocking antibody, and inhibiting mast cell degranulation, but a deleterious role in malignant melanoma, by impeding IgG1-mediated anti-tumor immunity. These findings highlight the importance of understanding the interaction between IgG4 and Fcγ receptors.

IgG4 是血清中代表性最少的人類 IgG 亞類，是一種有趣的抗體，具有獨特的生物學特性，例如能夠進行 Fab 臂交換並限制免疫複合物形成。缺乏效應功能，例如抗體依賴性細胞介導的細胞毒性和補體依賴性細胞毒性，對於治療目的來說是理想的。IgG4 通過充當阻斷抗體並抑制肥大細胞脫粒，在過敏中發揮保護作用，但通過阻礙 IgG1 介導的抗腫瘤免疫，在惡性黑色素瘤中發揮有害作用。這些發現強調了了解 IgG4 和 Fcγ 受體之間相互作用的重要性。

https://pubmed.ncbi.nlm.nih.gov/26497518/#:~:text=IgG4%2C%20the%20least%20represented%20human,and%20limit%20immune%20complex%20formation.

Immunoglobulin G4-related disease (IgG4-RD) is a chronic immune-mediated fibroinflammatory disorder that often manifests with tumor-like masses and/or painless enlargement of multiple organs. Serum IgG4 level is often but not always elevated. Symptoms depend on which organs are affected. Diagnosis generally requires biopsy. Treatment is with corticosteroids and sometimes rituximab.

免疫球蛋白 G4 相關疾病 (IgG4-RD) 是一種慢性免疫介導的纖維炎症性疾病，通常表現為腫瘤樣腫塊和/或多器官無痛性腫大。血清 IgG4 水平經常但並不總是升高。症狀取決於受影響的器官。診斷一般需要活檢。治療方法是使用皮質類固醇，有時使用利妥昔單抗。

https://www.merckmanuals.com/en-ca/professional/musculoskeletal-and-connective-tissue-disorders/igg4-related-disease/igg4-related-disease#:~:text=Immunoglobulin%20G4%2Drelated%20disease%20(IgG4,often%20but%20not%20always%20elevated.