Spencer A, Vulliamy T, Kaeda J, Goldman J M, Melo J V
Haematology Unit, Mater Hospital, Newcastle, NSW, Australia.
Leukemia. 1997 Feb;11(2):195-201. doi: 10.1038/sj.leu.2400543.
We have sought the presence of rearrangements of the immunoglobulin heavy chain gene locus in 13 patients with chronic myeloid leukemia (CML) in lymphoid blastic transformation (L-BT) using the polymerase chain reaction (PCR). The lymphoid nature of the transformation was confirmed by immunophenotyping and/or Southern blot hybridization with a J(H) probe. Clonal rearrangements were detected in 85% of cases and two or more rearrangements were visible in 64% of informative cases. The pattern of V(H) gene family utilization revealed an apparent reduction in V(H)4 family gene usage but otherwise reflected the known proportion of each gene family in the germline repertoire. In six cases the third complementary determining regions (CDR3) of the predominant blast crisis clone/s were sequenced revealing minimal evidence of somatic mutation. No clonal changes were detected in the chronic phase leukemia cells collected more than 6 months before the onset of L-BT in three of these patients. Of the other three patients studied in chronic phase from 1 to 6 months before L-BT, two showed clonal rearrangements which differed in size from those present at L-BT. In one patient a V(H)3 to V(H)5-D(H)-J(H) substitution had occurred at least 3 months prior to L-BT. In the other patient, however, the sequence of the rearrangement present 5 months prior to L-BT was unrelated to the rearrangements at the time of L-BT indicating a pattern of clonal succession. We conclude that: (1) IgH gene rearrangements are detectable in the majority of patients with L-BT using PCR and the lymphoid lineage of blastic CML is most readily confirmed using consensus primers to the framework 3 region; (2) somatic mutation is uncommon; and (3) B lymphoid clones distinct from those identified later may be detected before overt lymphoid BT. The identification of such 'abortive' clones is evidence for clonal instability before the onset of transformation and might have prognostic value.
我们运用聚合酶链反应（PCR），探寻了13例处于淋巴母细胞转化期（L-BT）的慢性髓性白血病（CML）患者免疫球蛋白重链基因座重排情况。通过免疫表型分析和/或用J(H)探针进行Southern印迹杂交，证实了转化的淋巴细胞性质。在85%的病例中检测到克隆性重排，在64%的信息丰富病例中可见两种或更多种重排。V(H)基因家族利用模式显示V(H)4家族基因使用明显减少，但其他方面反映了种系库中每个基因家族的已知比例。对6例主要母细胞危象克隆的第三个互补决定区（CDR3）进行测序，发现体细胞突变的证据极少。在其中3例患者中，于L-BT发生前6个月以上采集的慢性期白血病细胞未检测到克隆性变化。在L-BT前1至6个月处于慢性期研究的另外3例患者中，2例显示出大小与L-BT时不同的克隆性重排。在1例患者中，至少在L-BT前3个月发生了V(H)3至V(H)5-D(H)-J(H)替换。然而，在另1例患者中，L-BT前5个月存在的重排序列与L-BT时的重排无关，表明存在克隆演替模式。我们得出结论：（1）使用PCR可在大多数L-BT患者中检测到IgH基因重排，使用针对框架3区的共有引物最容易证实母细胞性CML的淋巴细胞系；（2）体细胞突变不常见；（3）在明显的淋巴细胞性BT之前可能检测到与后来鉴定的不同的B淋巴细胞克隆。识别此类“流产”克隆是转化开始前克隆不稳定性的证据，可能具有预后价值。
