CLINICAL SIGNIFICANCE OF THE DETECTION OF MINIMAL RESIDUAL DISEASE IN CHILDHOOD B-ALL BY FLOW CYTOMETRY

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Expression of CD25 is a specific and relatively sensitive marker for the Philadelphia chromosome (BCR-ABL1) translocation in pediatric B acute lymphoblastic leukemia

Background: Precursor B acute lymphoblastic leukemia (B-ALL) is the most common cancer in children and overall, has an excellent prognosis. However, the Philadelphia chromosome translocation (Ph+), t(9;22)(q34;q11), is present in a small subset of patients and confers poor outcomes. CD25 (IL-2 receptor alpha chain) expression has been associated with Ph+ B-ALL in adults, but no similar study has been performed in pediatric B-ALL. Methods: A retrospective analysis of 221 consecutive pediatric patients with a diagnosis of B-ALL (blood and/or bone marrow) from 2009 to 2012 was performed to determine an association between Ph+ B-ALL and CD25 expression. A threshold of 25% was used to define positive cases for CD25 expression by flow cytometry. Results: There were 221 patients with a diagnosis of B-ALL ranging from 2 to 22 years (median, 6 years). Eight (3.6%) B-ALL patients were positive for the Philadelphia chromosome translocation (Ph+ B-ALL) and 213 were negative (Ph-negative B-ALL). CD25 expression was observed in 6 of 8 (75%) Ph+ B-ALL patients and 6 of 213 (2.8%) Ph-negative B-ALL patients. CD25 expression was significantly higher in Ph+ B-ALL compared to Ph-negative B-ALL, with median CD25 expression of 64% (range 0-93%) and 0.1% (range 0-91%), respectively (P ≤ 0.0002). Therefore, CD25 expression as a predictor of Ph+ B-ALL had 75% sensitivity, 97% specificity, 50% positive predictive value and 99% negative predictive value. Conclusions: CD25 expression is a specific and relatively sensitive marker for the identification of Ph+ B-ALL in the pediatric population.     

γ-Catenin-Dependent Signals Maintain BCR-ABL1+ B Cell Acute Lymphoblastic Leukemia

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髓源性抑制细胞改变对儿童急性B淋巴细胞白血病的影响

目的:探讨髓源性抑制细胞（MDSC）改变对儿童急性B淋巴细胞白血病（B-ALL）的影响。方法:采集B-ALL患儿诱导缓解治疗前与完全缓解后及正常儿童的外周血,检测MDSC（CD11b+CD33+）的数量及其两个亚群［M-MDSC（CD14+CD11b+CD33+）与G-MDSC（CD15+CD11b+CD33+）］的相对比例,同时检测MDSC的主要功能性物质精氨酸酶Ⅰ（ArgⅠ）与活性氧产物（ROS）的表达情况,另按危险度分层进行比较。结果:诱导缓解治疗前,B-ALL患儿的外周血MDSC（CD11b+CD33+）数量比例显著大于正常儿童（P＜0.01）,诱导缓解治疗结束后显著降低（P＜0.01）,但仍显著大于正常儿童（P＜0.01）;诱导缓解治疗前,外周血MDSC细胞亚群以G-MDSC（CD15+CD11b+CD33+）为主,诱导缓解治疗后以M-MDSC（CD14+CD11b+CD33+）为主（P＜0.01）;诱导缓解治疗前,B-ALL患儿外周血ArgⅠ与ROS表达水平均显著高于诱导缓解治疗后（P＜0.01）,且诱导缓解治疗后仍显著高于正常儿童（P＜0.01）;MDSC数量及其相关功能物质ArgⅠ、ROS的表达水平均与B-ALL的危险度分层呈明显正相关（P＜0.01）。结论:MDSC的G-MDSC亚群及功能物质ROS对儿童B-ALL发病有重要影响。     

B-cell acute lymphoblastic leukemia and isochromosome 7q

A 10-year-old girl with cytological and immunological characteristics of B-cell acute lymphoblastic leukemia is reported. Chromosomal analysis revealed the presence of t(8;14) and i(7q).