Roth M S, Weiner G J, Allen E A, Terry V H, Harnden C E, Boehnke M, Kaminski M S, Ginsburg D
Department of Medicine, University of Michigan, Ann Arbor 48109.
J Immunol. 1990 Jul 15;145(2):768-77.
We have previously identified Id- tumor vaiants that emerge after anti-Id mAb therapy of the murine B cell lymphoma 38C13. This report characterizes the molecular basis for these variants. By using a modification of the polymerase chain reaction (PCR), mu and kappa Ig loci were sequenced from nine Id- variants derived directly by anti-Id immunoselection in vivo. Ig kappa loci sequence analysis was also performed from 10 additional variants amplified directly from tumor cells in vitro without immunoselection. We demonstrate that the molecular mechanism underlying tumor cell escape in this model is the spontaneous emergence of variants that have undergone kappa L chain gene "re-rearrangement" before positive selection by the anti-Id antibody. A second round of re-rearrangement was also demonstrated to occur within primary tumor variants. Re-rearrangement of the 38C13 tumor cell Ig kappa locus is strongly biased toward use of variable kappa genes within the conserved V kappa-Ox1 gene family, although their use is not exclusive. With the use of RNA PCR re-rearrangement was documented to occur in vitro at a frequency of approximately 1.0 x 10(-5)/cell. These findings may have important implications for the application of anti-Id antibodies as a therapeutic approach for human lymphomas and for understanding of the Ig gene rearrangement process.
我们之前已鉴定出在对小鼠B细胞淋巴瘤38C13进行抗独特型单克隆抗体（anti-Id mAb）治疗后出现的Id-肿瘤变体。本报告阐述了这些变体的分子基础。通过对聚合酶链反应（PCR）进行改进，对在体内通过抗独特型免疫选择直接获得的9个Id-变体的μ和κ免疫球蛋白基因座进行了测序。还对另外10个在体外未经免疫选择直接从肿瘤细胞中扩增得到的变体进行了免疫球蛋白κ基因座序列分析。我们证明，在该模型中肿瘤细胞逃逸的分子机制是在抗独特型抗体进行阳性选择之前，已经发生κ轻链基因“重新重排”的变体的自发出现。在原发性肿瘤变体中也证实发生了第二轮重新重排。38C13肿瘤细胞免疫球蛋白κ基因座的重新重排强烈倾向于使用保守的Vκ-Ox1基因家族内的可变κ基因，尽管并非仅使用这些基因。通过RNA PCR证实重新重排在体外发生的频率约为1.0×10(-5)/细胞。这些发现可能对将抗独特型抗体作为人类淋巴瘤的治疗方法的应用以及对免疫球蛋白基因重排过程的理解具有重要意义。
