Establishment of human abzymes-generation system by using light chain shifting in human B cells

免疫系统识别和区分外来抗原的一种机制是通过产生大量不同的抗体分子库。这种多样性保护生物体免受广泛的病原体和毒性剂的侵害，并已被开发用于产生高亲和力选择性受体，用作诊断剂、分子探针和治疗剂。另一方面，自身抗体攻击自身作为抗原，这是大多数自身免疫性疾病的特征。抗体基因在B细胞发育过程中通过一系列位点特异性重组事件组装，统称为V（D）J重组。尽管在未成熟的B细胞中发生轻链位点的V（D）J重组，但我们发现在某些人抗体分泌型B细胞中，原始轻链被另一条轻链取代，这是由二次V（D）J重组（轻链移位）引起的。在用具有磷酸酶抑制活性的试剂（例如咖啡因和冈田酸，刺激蛋白激酶C的试剂）处理后可以诱导轻链移位，而增加细胞内cAMP和钙以及抑制丝氨酸/苏氨酸蛋白激酶的因子不诱导轻链移位。由轻链移位产生的轻链具有蛋白酶活性。

One mechanism whereby the immune system recognizes and distinguishes foreign antigens is by generating a large and diverse repertoire of antibody molecules. This diversity protects organisms from a wide range of pathogens and toxic agents and has been exploited to produce high affinity-selective receptors for use as diagnostics, molecular probes, and therapeutic agents. On the other hands, autoantibodies attack self as an antigen, which characterizes most autoimmune diseases. Although a number of possibilities have been investigated, the mechanism responsible for the production of autoantibodies remains unsolved.Antibody genes are assembled during B cell development through a series of site-specific recombination events collectively termed V(D)J recombination. Although the V(D)J recombination at the light chain loci occur in immature B cells, we have found that the original light chain is replaced with another light chain which results from secondary V(D)J recombination (light chain shifting) in some human antibody-secreting B cells. Light chain shifting can be induced upon treatment with agents with phosphatase inhibitory activity such as caffeine and okadaic acid, the agent that stimulates protein kinase C, whereas factors that increase intracellular cAMP and calcium, and inhibit serine/threonine protein kinase did not induce light chain shifting. A light chain that is resulting from the light chain shifting has a protease activity.