免疫球蛋白（immunoglobulin, Ig）是一类最重要的免疫分子，是B淋巴细胞的特有产物，分泌型Ig通过不同的机制发挥着重要的免疫防御作用，即抗体活性；膜结合型Ig是B细胞识别抗原受体（B cell antigen receptor, BCR），这是目前仍然写在国内外免疫学教材的经典概念。然而，近年来越来越多的研究证据表明，机体内还存在一类迄今未被关注的、非B细胞来源的Ig分子（non B-Ig），它们在可变区重排模式、表达调控及功能等方面有别于经典的Ig分子。non B-Ig的突出特点是在恶性转化的细胞中高水平表达，其表达水平与肿瘤的不良分化及不良预后密切相关；功能研究显示，non B-Ig促进肿瘤细胞的生长及生存，并参与肿瘤的发生及发展。研究提示，non B-Ig具有原癌基因的潜质，有可能成为多种肿瘤新的治疗靶点。

Immunoglobulin (Ig), one of the most important immune molecules, has been considered to be produced only by B lymphocytes. The membrane bound Ig on B cells is responsible for the recognition of antigen, and the secreted Ig (antibody) exerts the immune defense effect via several mechanisms. This is the classic concept that can be found in the contemporary textbooks of immunology. However, in recent years, an emerging large body of evidence has confirmed that in addition to the B cell-derived Ig, there is another class of Ig which is of non-IB cell origin (non B-Igs). The non B-Igs are different from those of the classical Igs about their VHDJH or VκJκ rearrangement pattern, expression regulation and function. Observably, the non B-Igs are frequently over expressed in many cancer cells, and correlated with poor cell differentiation and patients’ prognosis. Importantly, the non B-Igs could promote growth of cancer cells, and play importent role in the mechanism of tumor progression. These findings suggest that the non B-Ig behaves like potential proto-oncogenes, which may be useful for tumor therapy as novel targets.

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