二抗库的成熟需要类别转换重组 (CSR)（将 IgM 转换为其他免疫球蛋白 (Igs)）和体细胞超突变（促进高亲和力抗体的产生）。体内发生免疫反应或感染后，T 细胞依赖性和 T 细胞非依赖性抗原的激活会触发激活诱导的胞苷脱氨酶的激活，从而启动 CSR 过程。 CSR 能够改变抗体的功能特性，从而促进生物体的适应性免疫反应。 Ig CSR 缺陷的特征是 Ig 同种型的相对频率异常，是一种罕见的原发性免疫缺陷形式。阐明 Ig 多样化的分子基础对于更好地了解 Ig CSR 缺陷相关疾病至关重要，并可为临床诊断和治疗方法提供线索。在此，我们回顾了五种 Ig 同种型多样化的最新见解，并选择了几种经典疾病，包括高 IgM 综合征、华氏巨球蛋白血症、高 IgD 综合征、选择性 IgA 缺乏症、高 IgE 综合征、多发性骨髓瘤和伯基特淋巴瘤，以说明 Ig CSR 缺乏的机制。对 Ig CSR 潜在机制的研究对于推动日益精确的诊断和治疗方法具有巨大潜力。© 2024 作者。四川国际医学交流中心出版的MedComm

Maturation of the secondary antibody repertoire requires class-switch recombination (CSR), which switches IgM to other immunoglobulins (Igs), and somatic hypermutation, which promotes the production of high-affinity antibodies. Following immune response or infection within the body, activation of T cell-dependent and T cell-independent antigens triggers the activation of activation-induced cytidine deaminase, initiating the CSR process. CSR has the capacity to modify the functional properties of antibodies, thereby contributing to the adaptive immune response in the organism. Ig CSR defects, characterized by an abnormal relative frequency of Ig isotypes, represent a rare form of primary immunodeficiency. Elucidating the molecular basis of Ig diversification is essential for a better understanding of diseases related to Ig CSR defects and could provide clues for clinical diagnosis and therapeutic approaches. Here, we review the most recent insights on the diversification of five Ig isotypes and choose several classic diseases, including hyper-IgM syndrome, Waldenström macroglobulinemia, hyper-IgD syndrome, selective IgA deficiency, hyper-IgE syndrome, multiple myeloma, and Burkitt lymphoma, to illustrate the mechanism of Ig CSR deficiency. The investigation into the underlying mechanism of Ig CSR holds significant potential for the advancement of increasingly precise diagnostic and therapeutic approaches.© 2024 The Author(s). MedComm published by Sichuan International Medical Exchange & Promotion Association (SCIMEA) and John Wiley & Sons Australia, Ltd.