Farahat N, Lens D, Zomas A, Morilla R, Matutes E, Catovsky D
Academic Department of Haematology and Cytogenetics, Royal Marsden Hospital, London.
Br J Haematol. 1995 Nov;91(3):640-6. doi: 10.1111/j.1365-2141.1995.tb05360.x.
The immunological detection of minimal residual disease in B-lineage acute lymphoblastic leukaemia (ALL) has been hampered by the fact that the leukaemic cells represent the malignant counterparts of normal haemopoietic precursors expressing terminal deoxynucleotidyl transferase (TdT), CD10 and CD19. We have used quantitative double-labelling flow cytometry with standard fluorescent beads to convert the mean fluorescence to the number of antigen molecules per cell. The number of TdT, CD10 and CD19 molecules per cell was determined in normal B-cell precursors from 22 healthy donors and eight regenerating marrows from patients with various malignancies and in 20 cases of B-lineage ALL. In normal bone marrow we characterized two different B-cell populations: TdT+/CD10+/CD19+ and TdT-/CD10+/CD19+. We demonstrated a major difference in the level of expression of TdT, CD10 and CD19 between normal bone marrow and B-lineage ALL blasts. Normal TdT+ precursors have significantly higher number of TdT (> 100 x 10(3)) and lower number of CD10 (< 50 x 10(3)) and CD19 (< 10 x 10(3)) molecules per cell than B-lineage ALL blasts (< 100, > 50, > 10 x 10(3) molecules per cell respectively); these differences were statistically highly significant. Furthermore, regenerating marrows had a significantly higher percentage of B-cell precursors than healthy donors. This increase was at the expense of the TdT-/CD10+/CD19+ population which, in the context of B-lineage ALL, could be wrongly interpreted as evidence of relapse if TdT is not included in the analysis. Therefore the quantitative analysis of TdT combined with CD10 and CD19 may allow a clear distinction between normal precursors and minimal residual leukaemia in B-lineage ALL and avoid the pitfall of misinterpreting regenerating B-cells as evidence of relapse.
B 系急性淋巴细胞白血病（ALL）中微小残留病的免疫检测受到白血病细胞代表表达末端脱氧核苷酸转移酶（TdT）、CD10 和 CD19 的正常造血前体的恶性对应物这一事实的阻碍。我们使用带有标准荧光微球的定量双标记流式细胞术将平均荧光转换为每个细胞的抗原分子数。测定了来自 22 名健康供体的正常 B 细胞前体、8 例各种恶性肿瘤患者的再生骨髓以及 20 例 B 系 ALL 中每个细胞的 TdT、CD10 和 CD19 分子数。在正常骨髓中，我们鉴定出两种不同的 B 细胞群体：TdT+/CD10+/CD19+ 和 TdT-/CD10+/CD19+。我们证明了正常骨髓和 B 系 ALL 原始细胞之间 TdT、CD10 和 CD19 的表达水平存在重大差异。正常的 TdT+ 前体每个细胞的 TdT 分子数显著更高（>100×10³），而 CD10（<50×10³）和 CD19（<10×10³）分子数比 B 系 ALL 原始细胞少（分别为每个细胞<100、>50、>10×10³ 分子）；这些差异具有高度统计学意义。此外，再生骨髓中 B 细胞前体的百分比明显高于健康供体。这种增加是以 TdT-/CD10+/CD19+ 群体为代价的，如果在分析中不包括 TdT，在 B 系 ALL 的背景下，这可能会被错误地解释为复发的证据。因此，TdT 与 CD10 和 CD19 的定量分析可能有助于在 B 系 ALL 中明确区分正常前体和微小残留白血病，并避免将再生 B 细胞误判为复发证据的陷阱。
