用筑巢式逆转录酶／多聚酶链反应检测Ph1阳性白血病特异基因转录本

Detection of BCR-ABL fusion gene in Ph1 chromo-some positive leukemia by “nested” retrotran-scriptase/ polymerase chain reaction

应用筑巢式逆转录酶／多聚哪链反应（ＲＴ／ＰＣＲ）检则Ｐｈ１阳性白血病中因染色体易位ｔ（９；２２）听形成的ＢＣＲ－ＡＢＬ融合基因转录本，发现３种ＢＣＲ－ＡＢＬ异构体，即ｅｌａ２、ｂ２ａ２和ｂ３ａ２．应用这３种异构体的特异ＲＴ／ＰＣＲ体系，在１０例慢性粒细胞白血病（ＣＭＬ）中，检测到２种异构体，ｂ２ａ２或ｂ３ａ２。而在８例Ｐｈ１阳性急性淋巴细胞白血病（Ｐｈｌ＋ＡＬＬ）中，３种异构体均被检测到，且其中２例同时有ｅｌａ２与ｂ２ａ２或ｂ３ａ２两忡异构体。用筑巢式ＲＴ／ＰＣＲ可从１０５～１０６个正常细胞中检出１个Ｐｈ１阳性细胞，在２例Ｐｈ１＋ＡＬＬ缓解初期标本中，检测到ＢＣＲ－ＡＢＬ转录本，提示有残余白血病细胞，１例于缓解期４个月时复查仍为阳性，并于缓解５个月时复发。另１例于缓解８个月时复查转阴，且缓解至今已１８个月，故ＢＣＲ－ＡＢＬ融合基因的检测不仅有助了研究Ｐｈ１阳性白血病的发病机理，而且为该类疾病的诊断和缓解期监测提供了十分灵敏，特异的方法。

y using “nested” retrotranscriptase / poly-merase chain reaction (RT/PCR) technioue, we deternuned the expression patterns of the BCR-ABL fu-sion gene resulting from the chromosomal transloca-tion t (9; 22) in leukernias with Ph1 chromosome.Three distinct isoforms of fusion gene transcriptswere discovered : ela2, b2a2 and b3a2. In 10 cases ofchronic myelogenous leukernia (CML), only twotypes (b2a2 and b3a2) were observed. However, in 8cases of Ph1 chromosome positive acute lymphoblas-tic leukemia (Ph1+ALL) , all three types were de-tected, including two cases characterized by the coex-istence of ela2 and b2a2 or b3a2 types. Moreover,the RT/PCR procedure established in the presentstudy proved to be a very sensitive method, allowingthe detection of one leukemic cell among 10￣5～10￣6normal cells. Thus, a positive RT/PCR result wasobtained in two Ph1+ALL cases just afterchemotherapyinduced clinical remission (CR) , sug-gesting the presence of residual disease. One case re-mained RT/PCR positive four months after achievingCR and relapsed in the fifth month, while the othercase converted to RT/PCR negative eight months lat-er and is now in CR for 18 months. Therefore the de-tection of BCR-ABL fusion gene is of importance notonly in the study of the pathogenesis of Ph1+leukemias but also in their diagnosis and monitoringof minimal residual disease during CR.