Voso M T, Hohaus S, Moos M, Haas R
Department of Internal Medicine V, University of Heidelberg and German Cancer Research Center.
Blood. 1997 May 15;89(10):3763-8.
Follicular lymphoma (FL) is characterized in a significant proportion of cases by the t(14;18) chromosomal translocation, which results in the juxtaposition of the oncogene bcl-2 to the joining region of the immunoglobulin heavy chain (IgH) gene. Molecular sequence analysis indicates that the t(14;18) rearrangement occurs in a B-lymphoid progenitor cell at the time of IgH rearrangement. We were interested whether hematopoietic stem and progenitor cells as characterized by CD34 expression bear the translocation. Bone marrow (BM)-CD34+ cells were enriched from 14 patients with FL whose BM was known to be positive for bcl-2/IgH (major breakpoint region [MBR]). Six patients were in complete remission (CR), two patients were in partial remission (PR), and six patients had active disease. Six patients had histological BM involvement when the samples were obtained. Using an immunomagnetic selection device (MINI-MACS), a mean purity of 88.7% +/- 4% CD34+ cells was achieved. The CD34+ cells were further enriched by fluorescence activated cell sorting (FACS) using CD34 fluorescein isothiocyanate (FITC)- and CD19 phycoerythrin (PE)-conjugated antibodies. The IgH gene was rearranged in the CD34+/CD19+ cell subset of all patients assessed by polymerase chain reaction (PCR). This population is thought to represent the progenitor stage at which the bcl-2/IgH translocation occurs. The unseparated BM mononuclear cell fraction from all 14 patients was positive for bcl-2/IgH using a nested PCR, but the BM-CD34+ cell fraction and the respective CD34+/CD19+ subset were negative in 13 of these 14 patients. The one patient with a positive PCR signal in the CD34+ cell subset had a relapse with BM involvement. We conclude that CD34+ progenitor cells including CD34+/CD19+ B-cell progenitors are not involved in the malignant cell clone. These data are in agreement with a transgenic mouse model, which indicates that the malignant phenotype in FL is sustained by mature B cells.
在相当一部分病例中，滤泡性淋巴瘤（FL）的特征是存在t(14;18)染色体易位，这导致癌基因bcl-2与免疫球蛋白重链（IgH）基因的连接区并列。分子序列分析表明，t(14;18)重排在IgH重排时发生于B淋巴细胞祖细胞。我们感兴趣的是，以CD34表达为特征的造血干细胞和祖细胞是否携带这种易位。从14例FL患者的骨髓（BM）中富集BM-CD34+细胞，已知这些患者的BM中bcl-2/IgH（主要断裂点区域[MBR]）呈阳性。6例患者处于完全缓解（CR），2例患者处于部分缓解（PR），6例患者有活动性疾病。采集样本时，6例患者有组织学上的BM受累。使用免疫磁选装置（MINI-MACS），CD34+细胞的平均纯度达到88.7%±4%。使用CD34异硫氰酸荧光素（FITC）和CD19藻红蛋白（PE）偶联抗体，通过荧光激活细胞分选（FACS）进一步富集CD34+细胞。通过聚合酶链反应（PCR）评估，所有患者的CD34+/CD19+细胞亚群中的IgH基因均发生重排。该群体被认为代表了bcl-2/IgH易位发生时的祖细胞阶段。使用巢式PCR，所有14例患者未分离的BM单核细胞部分bcl-2/IgH呈阳性，但在这14例患者中的13例中，BM-CD34+细胞部分以及相应的CD34+/CD19+亚群呈阴性。CD34+细胞亚群中PCR信号阳性的1例患者出现了伴有BM受累的复发。我们得出结论，包括CD34+/CD19+ B细胞祖细胞在内的CD34+祖细胞不参与恶性细胞克隆。这些数据与转基因小鼠模型一致，该模型表明FL中的恶性表型由成熟B细胞维持。
