A New Algorithm and Panel Construction for Pediatric Leukemia Immunophenotyping Using 10-Color Flow Cytometry

Rapid identification and quantification of abnormal cell populations in minimal specimen are crucial for diagnosis and longitudinal minimal residual disease (MRD) testing of childhood leukemia. So far, most standard immunophenotypic analyses are performed using antibody panels with up to five-colors and require high cell numbers. For infant and pediatric specimen, high-level multicolor analyses is highly desirable to gather sufficient data for initial diagnostic and follow up monitoring of pathologic populations.

In this study, we aimed to establish a newly defined pediatric multicolor flow cytometric panel algorithm with high reliability yet minimal specimen requirement.

We defined a 10-color flow cytometric panel using the new violet laser dye “KromeOrange (KO)”. Applying CD45-KO/Side Scatter gating, combined with 2 additional backbone markers the panel is designed in two consecutive steps. In the first step, a single standardized 10-color-“screening tube” (FITC-HLA-DR, PE-CD15/CD56, ECD-CD5, PC5.5-CD33, PC7-CD13, APC-CD117, APC A700-CD34, APC A750-CD19, PB-CD3, KrO-CD45) is applied for initial orientation of specific lineage assignment. Based on results obtained with the screening tube, a specific multi-tube “classification panel” is used to complete detailed characterization of lineage specific malignancy and maturation stage. Suitable specimens include fresh blood, bone marrow and all body fluids. All samples are stained directly with monoclonal antibodies, followed by the lyses of erythrocytes and a short wash. Compared to standard five color panel previously used the application of greater numbers of informative antibodies in the screening tube and in the 2^ndstep muti-tube classification panel is cost and time efficient and results in a more precise characterization of any single event.

Our panel construction and algorithm definition for infant and pediatric leukemia immunophenotyping is one of the first 10-color flow cytometry panels described for this application. Advantages are the possibility to obtain highly specific information from minimal specimens with significantly improved laboratory efficiency. The overall performance is currently tested in a routine clinical setting.

No relevant conflicts of interest to declare.