Berinstein N L, Jamal H H, Kuzniar B, Klock R J, Reis M D
Department of Medicine/Immunology, University of Toronto, Canada.
Leukemia. 1993 Jan;7(1):113-9.
The t(14;18) chromosomal translocation occurs in most follicular non-Hodgkin's lymphomas and places the Bcl-2 gene on chromosome 18q21 into the immunoglobulin JH region on chromosome 14q32. This translocation can be exploited to detect clonal malignant cells bearing this genetic alteration. A polymerase chain reaction (PCR) assay amplifying over the major breakpoint region (mbr) and minor cluster region (mcr) was developed and optimized. In this report, the sensitivity and reproducibility of this semiquantitative assay, performed on a relatively large number of clinical samples is shown. A titration curve of DNA made from a t(14;18)- cell line admixed with increasing ratios of a t(14;18)+ cell line was used to demonstrate that one t(14;18)+ cell in 100,000 t(14;18)- cells could reproducibly be detected. Occult lymphoma cells, not detected by standard morphologic analysis, were demonstrated in almost two-thirds of the bone marrow and peripheral blood specimens obtained from untreated patients with follicular lymphoma. Of 11 bone marrow samples assessed, seven were positive for occult disease by PCR amplification over the mbr and one was positive over the mcr. Of these six positive marrow samples, only three had been reported positive by standard morphologic criteria. In addition, seven of nine peripheral blood samples assessed were positive over the mbr and one additional sample was positive over the mcr. None of these were morphologically positive. Seven of the above patients would have been upstaged if these results were utilized for staging, including two of three patients with stage I or stage II disease. PCR-detectable occult disease persisted in four of four patients assessed both pre- and post-treatment, even after aggressive multi-drug combination chemotherapy in two of these patients. The clinical significance of detecting this occult disease must await the study of larger numbers of patients and the clinical outcomes of patients with occult disease and patients without occult disease.
t(14;18)染色体易位发生于大多数滤泡性非霍奇金淋巴瘤中，使位于18q21染色体上的Bcl-2基因易位至14q32染色体上的免疫球蛋白JH区域。这种易位可用于检测携带这种基因改变的克隆性恶性细胞。一种针对主要断裂点区域（mbr）和次要簇区域（mcr）进行扩增的聚合酶链反应（PCR）检测方法得以开发并优化。在本报告中，展示了该半定量检测方法在相对大量临床样本上的敏感性和可重复性。用由t(14;18)-细胞系制备的DNA与比例不断增加的t(14;18)+细胞系混合制作滴定曲线，结果表明在100,000个t(14;18)-细胞中可重复检测到1个t(14;18)+细胞。在从未经治疗的滤泡性淋巴瘤患者获取的骨髓和外周血标本中，近三分之二检测到了标准形态学分析未发现的隐匿性淋巴瘤细胞。在评估的11份骨髓样本中，7份通过mbr区域的PCR扩增检测到隐匿性疾病呈阳性，1份通过mcr区域检测呈阳性。在这6份阳性骨髓样本中，只有3份按标准形态学标准报告为阳性。此外，在评估的9份外周血样本中，7份通过mbr区域检测呈阳性，另有1份通过mcr区域检测呈阳性。这些样本在形态学上均未呈阳性。如果将这些结果用于分期，上述7名患者的分期将会提高，其中包括3名I期或II期疾病患者中的2名。在接受评估的4名患者中，无论治疗前还是治疗后，即使其中2名患者接受了积极的多药联合化疗，PCR可检测到的隐匿性疾病在这4名患者中均持续存在。检测到这种隐匿性疾病的临床意义必须等待对更多患者的研究以及对有隐匿性疾病患者和无隐匿性疾病患者临床结局的研究。
