Tandem Application of Flow Cytometry and Polymerase Chain Reaction for Choice Targets of Minimal Residual Disease in Childhood Acute Lymphoblastic Leukemia.

Objective In order to allow monitoring virtually all patients with childhood acute lymphoblastic leukemia for minimal residual disease in resource-poor countries or patient population. Methods Choice targets of minimal residual disease using tandem application of multi-parameter flow cytometry with various combinations of monoclonal antibodies for leukemia-associated immunophenotypes and polymerase chain reaction (PCR) of clonal T-cell receptor or immunoglobulin gene rearrangements was performed in 122 patients with newly diagnosis acute lymphoblastic leukemia on protocol ALL-XH-99. Results [circ1]The four-color antibody combinations consisted of CD₁₀/CD₃₄/CD₁₉ plus another effective marker such as CD₃₈, CD₆₅, CD_66c, and CD₂₁. 106 cases of childhood B-cell precursor acute lymphoblastic leukemia were screening for antibodies combinations of interest and were identified in 95 of 106 cases (89.62%). The frequency of terminal deoxynucleotidyl transferase (TdT) in the immunophenotypic expression of leukemia cells is 59.43%, and then does CD₃₈ and CD₅₈. There is only one aberrant immunophenotype in 11 of 95 cases (11.58%) and most cases (88.42%) express at least two suitable combinations. [circ2] Due to lack of specimens in the leukemia cell bank, polymerase chain reaction of clonal T-cell receptor or immunoglobulin gene rearrangements was performed in 27 patients with newly diagnosis acute lymphoblastic leukemia including 7 cases with B-cell precursor ALL who were not detected targets of minimal residual disease by multi-parameter flow cytometry and 20 cases with T-lineage acute lymphoblastic leukemia (25 patients with T-ALL at the same time in our hospital). In 17 samples (65.38%), two or more monoclonal/bi-allelic gene rearrangements were identified, in 9 of 27 cases (34.62%), only one monoclonal rearrangement was detectable, and in one case no clonal T-cell receptor or immunoglobulin gene rearrangement could be identified. The vast majority (70%) of T-lineage ALL contain T-cell receptor VγI-Jγ1.3/2.3, and then T-cell receptor Vδ1-Jδ1, T-cell receptor VγIII-Jγ1.3/2.3. In B-cell precursor ALL, the high frequency of T-cell receptor VγI-Jγ1.3/2.3 emerged, and then the Kde rearrangements of IGK. Cross-lineage T-cell receptor rearrangements are found in many patients (57.14%) with B-lineage acute lymphoblastic leukemia. [circ3]Tandem application of multi-parameter flow cytometry with various combinations of monoclonal antibodies for leukemia-associated immunophenotypes and polymerase chain reaction (PCR) of clonal T-cell receptor or immunoglobulin gene rearrangements to detect MRD targets was investigated in 122 patients. Almost all patients except one case were detected suitable immunophenotypic abnormalities or antigen receptor gene rearrangements targets. Tandem application of two methods allows monitoring virtually all patients (99.18%) for MRD. Conclusion Choice targets of minimal residual disease using tandem application of flow cytometric detection of aberrant immunophenotypes, polymerase chain reaction (PCR) of clonal T-cell receptor or immunoglobulin gene rearrangements was to allow monitoring virtually in resource-poor countries or patient population for minimal residual disease.