Szczepański T, Willemse M J, van Wering E R, van Weerden J F, Kamps W A, van Dongen J J
Department of Immunology, University Hospital Rotterdam/Erasmus University Rotterdam, The Netherlands.
Leukemia. 2001 Sep;15(9):1415-23. doi: 10.1038/sj.leu.2402206.
The IGH gene configuration was investigated in 97 childhood precursor-B-ALL patients at initial diagnosis. Rearrangements were found by Southern blotting in all but three patients (97%) and in 30 cases (31%) we observed oligoclonal IGH gene rearrangements. Heteroduplex PCR analysis revealed at least one clonal PCR product in all Southern blot-positive cases. In 89 patients (92%) complete V(D)J rearrangements were found, while incomplete D(H)-J(H) rearrangements occurred in only 21 patients (22%). In 5% of cases the D(H)-J(H) rearrangements were the sole IGH gene rearrangements. Sequence analysis of the 31 identified incomplete rearrangements revealed preferential usage of segments from the D(H)2, D(H)3 and D(H)7 families (78%). While D(H)2 and D(H)3 gene rearrangements occur frequently in normal B cells and B cell precursors, the relatively frequent usage of D(H)7-27 (19%) in precursor-B-ALL patients is suggestive of leukemic transformation during prenatal lymphopoiesis. Among J(H) gene segments in the incomplete D(H)-J(H) rearrangements, the J(H)6 segment was significantly overrepresented (61%). This observation together with the predominant usage of the most upstream D(H) genes indicates that many of the identified clonal D(H)-J(H) gene rearrangements in precursor-B-ALL probably represent secondary recombinations, having deleted pre-existing D(H)-J(H) joinings. The patients with incomplete D(H)-J(H) gene rearrangements were frequently characterized by hyperdiploid karyotype with additional copies of chromosome 14 and/or by IGH oligoclonality. The presence of incomplete D(H)-J(H) joinings was also significantly associated with a less mature immunogenotype: overrepresentation of V(H)6-1 gene segment usage, absence of biallelic TCRD deletions, and low frequency of TCRG gene rearrangements. This immature immunogenotype of precursor-B-ALL with incomplete IGH gene rearrangements was not associated with more aggressive disease.
对97例初诊儿童前体B淋巴细胞白血病（precursor - B - ALL）患者的IGH基因构型进行了研究。除3例患者（3%）外，其余所有患者（97%）均通过Southern印迹法检测到重排，并且在30例患者（31%）中观察到寡克隆IGH基因重排。异源双链PCR分析显示，在所有Southern印迹阳性病例中均至少有一个克隆性PCR产物。89例患者（92%）发现了完整的V(D)J重排，而仅21例患者（22%）出现了不完整的D(H)-J(H)重排。在5%的病例中，D(H)-J(H)重排是唯一的IGH基因重排。对31个鉴定出的不完整重排进行序列分析，结果显示D(H)2、D(H)3和D(H)7家族的片段使用频率较高（78%）。虽然D(H)2和D(H)3基因重排在正常B细胞和B细胞前体中经常发生，但前体B淋巴细胞白血病患者中D(H)7 - 27的相对频繁使用（19%）提示在产前淋巴细胞生成过程中发生了白血病转化。在不完整的D(H)-J(H)重排中的J(H)基因片段中，J(H)6片段明显过度表达（61%）。这一观察结果与最上游D(H)基因的主要使用情况表明，在前体B淋巴细胞白血病中鉴定出的许多克隆性D(H)-J(H)基因重排可能代表二次重组，已经删除了先前存在的D(H)-J(H)连接。具有不完整D(H)-J(H)基因重排的患者常表现为超二倍体核型，伴有额外的14号染色体拷贝和/或IGH寡克隆性。不完整的D(H)-J(H)连接的存在也与免疫基因型不成熟显著相关：V(H)6 - 1基因片段使用过度、双等位基因TCRD缺失缺失以及TCRG基因重排频率较低。这种具有不完整IGH基因重排的前体B淋巴细胞白血病的不成熟免疫基因型与侵袭性更强的疾病无关。
