Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
Scand J Immunol. 2020 Oct;92(4):e12921. doi: 10.1111/sji.12921. Epub 2020 Jul 16.
Antibodies forming a complex with antigen in vivo can dramatically change the antibody response to this antigen. In some situations, the response will be a 100-fold stronger than in animals immunized with antigen alone, and in other situations, the response will be completely suppressed. IgG is known to suppress the antibody response, for example to erythrocytes, and this is used clinically in Rhesus prophylaxis. The mechanism behind IgG-mediated immune suppression is still not understood. Here, we will review studies performed in experimental animal models and discuss the various hypotheses put forward to explain the profound suppressive effect of IgG. We conclude that an exclusive role for negative regulation of B cells through FcγRIIB, increased clearance of erythrocytes from the circulation or complement-mediated lysis is unlikely. Epitope masking, where IgG hides the epitope from B cells, or trogocytosis, where IgG removes the epitope from the erythrocyte, is compatible with many observations. These two mechanisms are not mutually exclusive. Moreover, it cannot be ruled out that clearance, in combination with other mechanisms, plays a role.
在体内与抗原形成复合物的抗体可以显著改变机体对该抗原的抗体反应。在某些情况下，反应强度比单独用抗原免疫的动物强 100 倍，而在其他情况下，反应完全受到抑制。IgG 已知可抑制抗体反应，例如针对红细胞的反应，临床上用于恒河猴预防。IgG 介导的免疫抑制背后的机制尚不清楚。在这里，我们将回顾在实验动物模型中进行的研究，并讨论提出的各种假说，以解释 IgG 的强烈抑制作用。我们得出结论，通过 FcγRIIB 对 B 细胞的负调控、循环中红细胞的清除增加或补体介导的裂解的排他作用不太可能。表位掩蔽，即 IgG 将表位从 B 细胞隐藏起来，或 trogocytosis，即 IgG 将表位从红细胞中移除，与许多观察结果一致。这两种机制并非互斥。此外，不能排除清除与其他机制相结合发挥作用的可能性。
