An experimental mouse model of spontaneous generation of HodgkinDisease by introduction of GANP RNA-primase gene

我们研究了诱导小鼠淋巴瘤的分子。生发中心B细胞在T细胞依赖的抗原免疫刺激下迅速增殖成熟，在生发中心B细胞中发现了β-RNA底物酶GANP。丢失的GANP小鼠没有表现出明显的异常，但表现出缺乏产生高亲和力抗体的能力，免疫球蛋白的体细胞超突变减少。V区基因与抗原刺激有关。这些小鼠缺乏高亲和力类型的突变。转基因策略中GANP的高表达进一步证实了GANP的作用，这清楚地表明了抗原驱动的B细胞的体细胞高突变率和高亲和型突变。为了进一步证明这一点，我们通过在克隆水平上测量特定抗体的亲和力来研究抗体的亲和力。用硝基苯基-鸡g-球蛋白和…免疫后，产生了6,000多株单抗进一步建立分泌抗NP特异性抗体的杂交瘤细胞株。GANP-Tg小鼠产生的抗半抗原NP的单抗亲和力较高，为Kd×109M，而野生型对照的亲和力较低。有趣的是，在O57BL/6小鼠系统中，高亲和力的单抗是由体细胞超突变较多的V区产生的，并使用了非规范的V区基因。这些结果表明，GANP通过调节V区突变的诱导和/或B细胞克隆扩增过程中DNA损伤的修复和生发中心区的选择，参与了抗原免疫后高亲和力B细胞的产生。用抗GANP特异性和磷酸化GANP特异性单抗进行组织化学分析，检测到GANP在淋巴瘤组织中的表达极高。人霍奇金淋巴瘤中，Read-Sternberg细胞表现出较高的表达。该单抗可用于检测人类HD临床标本中常见的淋巴瘤混合群体中的恶性细胞。我们研究了GANP表达增加是否可能是小鼠淋巴瘤的一个致病因素。GANP-TG诱发的非B/非T细胞型淋巴瘤与老年组自发性HD淋巴瘤十分相似。这些结果表明，GANP的增强和异常表达是小鼠HD样淋巴瘤的一个致病因素。我们推测，这些额外的因素与淋巴瘤的发生有关，可能与各种病毒的感染和外周淋巴器官的免疫系统的应激有关。较少

We investigated the molecule that induces lymphomas in mouse. Beta RNA primase GANP was found in germinal center B cells that are rapidly proliferating and maturating upon stimulation with T cell-dependent antigen immunization in vivo. Loss of GANP mice displayed no apparent abnormalities but showed a lack of generation of high-affinity antibody production with reduced somatic hypermutation of immunogolobulin. V-region genes with respect to the antigen stimulation. The mice lacked the high-affinity type mutations. The effect of GANP was further confirmed by the over expression of GANP using transgenic strategy, that clearly indicated the augmented somatic hypermutation rates and the high-affinity type mutations in antigen driven B cells. To prove this further, we studied the affinity of the antibodies by measuring the affinity of the specific antibodies at the monoclonal level. More than 6000 monoclonal antibodies were generated after immunization with nitrophenyl-chicken g-globulin an … More d establishment of the hybridomas secreting anti-NP specific antibodies. GANP-trangenic (GANP-Tg) mice generated the monoclonal antibodies with higher affinity to the hapten NP as KD×109M in comparison with the lower affinities from the wild-type littermate controls. Interestingly, the high affinitymonoclonal antibodies were generated by the V-regions with more somatic hypermutations and using the non-canonical V-region gene in a system of O57BL/6 mice system. These results indicated that GANP is involved in generation of high-affinity B cells upon immunization with antigen by regulating the induction of V-region mutations and/or the repair of the DNA damage during B cell clonal expansion and the selection in germinal center regions.The expression of GANP was detected extremely high in the lymphoma specimens by histochemical analysis with anti-GANP specific and the phosphorylated GANP-specific monoclonal antibodies. Human Hodgkin lymphoma, Read-Sternberg cells displayed the higher expression. The monoclonal antibodies were useful for detection of the malignant cells in the mixed population of the lymphomas often observed in human HD clinical samples. We examined whether the increased expression of GANP could be a causative factor of lymphomas in mice. GANP-Tg generated lymphomas of non-B/non-T cell type as quite similar to the human HD lymphomas spontaneously in aged group. These results indicated that the augmented and abnormal expression of GANP is a causative factor of lymphomas of HD-like lymphomas in mice. We speculated that the additional factors are involved in the generation of lymphomas, presumably associated with the infections with various viruses and the stresses of the immune system in peripheral lymphoid organs. Less