| Background and Objective Acute lymphocytic leukemia is a common malignant hematologic disease in childhood. The incidence of 85% of the acute lymphoblastic leukemia is B-lineage Acute Lymphocytic Leukemia. Through regular and union chemotherapy, complete remission rate of acute lymphocytic leukemia in children has reached more than 90% and 5-year survival rate has reached 80%. However, relapse in patients who had a complete remission remains the biggest obstacle during the course of treatment of leukemia. The root causes of relapse are remaining minimal residual leukemia cells in bone marrow and blood. At present, multiparameter flow cytometry(FCM) which is a fast, accurate and convenient method is the most commonly used method to detect Minimal Residual Disease In clinical. The key point of MRD detection in FCM is to choose the sensitive and specific combination of immune phenotype, which is able to identify normal cells and leukemic lymphoblasts. Lymphocyte function-associated antigen-3(CD58), a member of the Ig superfamily, express in kinds of cells in bone marrow. It demonstrated overexpressed in precursor-B acute lymphoblastic leukemia than adult when compared with their normal counterparts, suggesting CD58 has the potential in the detection of minimal residual disease by flow cytometry. In addition, no attention of CD58 expression characteristics in children ALL is discussed. This study taked the B-ALL patients in childhood as the research object, is to analyze the expression of CD58 in B-ALL in children and its stability and accuracy in MRD detection at clinically relevant time points.Methods We studied 87 B-ALL patients when they were at diagnosis in pediatric department of the first affiliated hospital of Zhengzhou University. We analyzed the CD58 expression in B-ALL of children(at diagnosis,at day+19 and at day+33), choosing the immune phenotype combination of CD58/CD10/CD19/CD45 by flow cytometry. According to the principle of matching in age and gender, we selected 20 cases of children with iron deficiency anemia and 5 cases of T- ALL children who get complete remission after induction chemotherapy as control group. In follow-up samples from day +33 when they had get complete remission,the MRD level was simultaneously evaluated by real-time quantitative polymerase chain reaction(RQ-PCR) amplification of antigen receptor genes and FCM.Results(1)The overall average MFI of CD58 in 87 children with B-ALL was 90.82±33.23, which was 13.52 ± 6.27 in normal B lymphocyte of the control group consisting of 20 children with iron deficiency anemia(IDA). It is a a significant relation between them. CD58 expression was significantly higher in B-ALL blasts than in normal B lymphocytes(t=10.33,P<0.001).(2)The overall average MFI of CD58 in 5 children with T-ALL was15.34±4.19, which is significantly lower than in B-ALL blasts. The children with T-ALL had a complete remission state. The difference was statistically significant(t=9.746,P<0.01), while no significant differences of CD58 expression between normal B lymphocytes and regenerating B lymphocytes of T-ALL(t=0.611,P=0.506).(3)The CD58 expression in 38 B-ALL children at day+19 during the regular chemotherapy is significant different from at diagnosis.The overall average MFI of CD58 was 106.57±25.90 at diagnosis, and it was 100.48±22.31 at day+8.No significant differences is found(t=0.801,P=0.428).(4)According the distribution characteristics of B- ALL blasts and normal B precursor cells in CD58 and CD10 double parameters figure by flow cytometry, 44 cases of 87 children with B-ALL can apply combination of CD58/CD10/CD19/CD45 to detect MRD. The coverage of this combination is 55.1%.(5)The MRD level of 44 B-ALL children who had a high expression of CD58 had been evaluated simultaneously by real time quantitative polymerase chain reaction(RQ-PCR) and FCM(combination of CD58/CD10/CD19/CD45). Results of FCM is 9 cases for positive and 39 cases for negative,while results of RQ-PCR is 11 cases for positive and 37 cases for negative. They had a consistent result(95.8%).No significant differences is found between the methods(χ2=0.50,P=0.500).(6)In follow-up samples from day+33, it had 11 positive cases in children who had a high expression of CD58, however it had 23 negative cases in children of a lower expression of CD58.The positive rate of MRD detection by FCM was significantly lower in CD58 over expression group(χ2=6.340,P=0.012).Conclusion CD58 is widely expressed in B acute lymphocytes of children with B-ALL. CD58 overexpress in B acute lymphoblastic leukemia blasts when compared to normal counterparts. CD58 is a very stable immunophenotypic marker in lymphocytes, suggesting it used as an indicator for detection of MRD in B-ALL children at critical time points, which would enrich the combination of MRD detection and coverage. |
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