免疫球蛋白κ链的结构功能及其在疾病发生发展过程中的作用

免疫球蛋白κ（Igκ）链是免疫球蛋白的一条轻链。免疫球蛋白基因主要由3个不同的基因位点组成，κ链、 λ链、重链。正常情况下免疫球蛋白轻链与免疫球蛋白重链结合形成功能性的免疫球蛋白复合物。κ或λ游离轻链 （FLCs）是由B淋巴细胞在免疫球蛋白合成过程中产生的，过去认为FLCs没有任何功能，但是目前证实FLCs参与了 免疫应答的几个关键过程，在不同的疾病中FLCs浓度高低与病程预后有极大的相关性。FLCs会导致肥大细胞脱颗 粒，如炎症性肠病中肥大细胞会释放炎性介质，并刺激局部炎症反应。而且在一些自身免疫性疾病中FLCs浓度的水 平也显著升高。FLCs不仅对非肿瘤性疾病中有一定的影响，肿瘤组织浸润的B淋巴细胞分泌Igκ，且Igκ的表达水平 与肿瘤的发生、发展密切相关。本文主要就Igκ的结构功能及其在疾病发生过程中的作用进行综述。

The structure and function of immunoglobulin kappa chain and its role in the development of diseases

Immunoglobulin kappa chain (Igκ) is a light chain of immunoglobulin. The immunoglobulin gene consists of three different loci, including κ chain, lambda (λ) chain and heavy chain. In normal, the light chain of immunoglobulin usually binds with heavy chain to form functional immunoglobulin complex. Free κ or λ light chains (FLCs) can be produced in the process of immunoglobulin synthesis by B lymphocytes. It was thought that FLCs had no function, but now it has been reported that FLCs participate in several key processes of immune response. The concentration of FLCs is closely correlated with the prognosis of different diseases. FLCs can promote mast cell degranulation, resulting in the releasing of inflammatory mediators in inflammatory bowel disease. Furthermore, the high level of FLCs can be also detected in some autoimmune diseases. Besides the role of FLCs in non-tumor diseases, Igκ secreted by B lymphocytes in tumor stroma is related to tumor initiation and development. Here, we reviewed the structure and function of Igκ and its role in the pathogenesis of diseases.