Method establishment of minimal residual disease in B lineage acute lymphoblastic leukemia by 8- color flow cytometric detection / 中华检验医学杂志

ABSTRACT

Objective To establish and evaluate the new method of 8-color flow cytometry (8c-FCM) with two tube detecting bone marrow minimal residual disease (MRD) in B lineage acute lymphoblastic leukemia (B-ALL).MethodsThe MRD cells were analyzed by using two combinations of 8c-FCM antibody panels,gating with CD19/Side scatter(SSC),CD45/CD10 and CD34(or cTdT).Nalm-6 cell of B-ALL was mixed into normal marrow cells,with proportion of 10.00％,1.00％,0.10％,0.01％and 0.005％,and recovery test and reproducibility test were carried with 8c-FCM established to value its accuracy and precision of.Fluorescence intensity was detected on different time points after marked Nalm-6 by antibodies to evaluate the fluorescent stability of the antibodies.The immunophenotyping was analyzed in 39 bone marrow specimens,including 9 cases of normal control,9 cases of B-ALL primary or recurrent,21 cases of complete remission (CR) after chemotherapy or bone marrow transplantation ( BMT),to evaluate the detection of normal B lymphocyte lineage,leukemia cells of B-ALL,MRD cells of B-ALL using the 8c-FCM and compare it with 4c-FCM in being.ResultsThe method of two tube 8c-FCM with main antibodies of CD19,CD45 and CD10 to detect MRD of B-ALL was founded; CV ＜ 2.5％,average recovery rate was 95.81％,when the actual percent of Nalm-6 mixed into normal bone marrow≥0.10％,and the percent of Nalm-6 detected and actual was linear dependent ( r =0.99,P ＜ 0.05 ) ranged from 10.00％ - 0.01 ％,when 106 cells were acquired ; the sensitivity of the method established could reach 0.01％.The fluorescent intensity decreased along with the time after Nalm-6 cell marked,but less than 10％ in 24 hours.Using the antibody combinations and analyze strategy,the immunophenotye of B lymphocyte in normal bone marrow presented four sequential stages:Stage Ⅰ CD45low/CD10stro/CD20 -/CD38stro/CD34 + or cTdT +,Stage ⅡCD45 +/CD10 + / CD20 -/CD38stro/CD34+ or cTdT +,Stage Ⅲ CD45 +/CD10 +/CD20 -/CD38stro/CD34 -or cTdT-,Stage Ⅳ CD45stro/CD10 -/CD20 +/CD38low/CD34or cTdT.Antigen expressions of leukeamic cells of B-ALL primary or recurrent were different compared with control team; there were 5 cases with MRD positive in CR team,and the main antigen expression was consistent with the results from 4c-FCM.The range of the percent of MRD cells was 0.02％ - 5.42％ of the 5 cases of MRD positive.ConclusionsThe new method of two tube 8c-FCM established shows good reproducibility and high accuracy,and can identify normal B lymphocyte populations in bone marrow and regenerated B-precursors in CR cases with MRD cells;compared with 4c-FCM,the new method of two tube 8c-FCM with the fewer specimen is faster and efficient to diagnose MRD of B-ALL.