| Objective To investigate the value of detecting minimal residual disease (MRD) and immunophenotypes by flow cytometry(FCM) in B-lineage acute lymphoblastic leukemia (B-ALL) and clinical significance.Methods 39 children with B- ALL were enrolled at diagnosis and immunophenotypes were detected by FCM. After complete remission, follow-up bone marrow(BM) samples were taken on 5 standardized time points (d33, 3m, 6m, 9m and 12m of chemotherapy) and MRD was monitored. This study was carried out on 122 BM samples. Gating was performed using the CD45-SSC plot. Various combinations with two monoclonal antibodies among CD19, CD10, CD20 and CD22 were analyzed with three-color stainings. CD33 and CD13 were used as myeloid antibodies for B-ALL with myeloid markers.Results (1)The positive rates of CD19, CD22 and CD10 were 94.87%, 92.31%, and 87.18% respectively. The positive rates of CD20 was only 15.38%. CD13 and CD33 were expressed in 33.33% children with B-ALL, in which 8 cases of CD13 positive and 5 cases of CD33 positive were included. (2)During early 6 months, level of MRD more than 10-4 was associated with a higher risk of relapse (P<0.05) . While on 9m and 12m, relapse rates between group with level of MRD more than 10-4 and group with MRD level less than 10-4 were not different significantly.(3)Survival analyses indicated that early MRD level (> 10-4) was high risk factor of B-ALL relapse (P=0.005) .(4) 2 of 6 patients with recurrence had consistent higher level of MRD(>10-4) in the BM, even to 10-2 . (5) Higher levels of MRD had been detected 1-4 months prior to relapse even morphological complete remission was present.Conclusions (1)Flow cytometry can be used to define MRD in the majority of children with B-ALL and predict clinical outcomes. It is also reliable, simple, sensitive and fast. (2)Patients with MRD levels > 10-4 in early treatment period have poor prognosis. MRD may be an independent risk factor of relapse. |
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