Immunophenotypic characterization of leukemic cells with the use of flow cytometry (FC) is a fundamental tool in acute lymphoblastic leukemia (ALL) diagnostics. A variety of genetic aberrations underlie specific B-cell precursor ALL (BCP-ALL) subtypes and their identification is of great importance for risk group stratification. These aberrations include: ETV6::RUNX1 fusion gene, Philadelphia chromosome (BCR::ABL1 fusion gene), rearrangements of the KMT2A, TCF3::PBX1 fusion gene and changes in chromosome number (hyperdiploidy and hypodiploidy). Diagnostic panels for BCP-ALL usually include B-cell lineage specific antigens: CD19, CD10, CD20, maturation stage markers: CD34, CD10, CD38, TdT, IgM and other markers useful for possible genetic subtype indication. Some genetic features of leukemic cells (blasts) are associated with expression of certain antigens. This review comprehensively summarizes all known research data on genotype-immunophenotype correlations in BCP-ALL. In some cases, single molecules are predictive of particular genetic subtypes, i.e., NG2 with KMT2A gene rearrangements or CD123 with hyperdiploidy. However, much more information on possible genotype or prognosis can be obtained with wider (≥8-color) panels. In several studies, a quantitative antigen expression scale and advanced statistical analyses were used to further increase the specificity and sensitivity of genotype/immunophenotype correlation detection. Fast detection of possible genotype/immunophenotype correlations makes multicolor flow cytometry an essential tool for initial leukemia diagnostics and stratification.

Childhood acute lymphoblastic leukemia (ALL) is the most common pediatric cancer, and while chemotherapy has significantly improved survival rates, it can also lead to long-term side effects, including immune system dysfunction. This study aimed to investigate in detail, using flow cytometry, the T-cell subpopulations in the peripheral blood of children who have completed ALL treatment and compare them to a group of healthy children. The study group consisted of 20 patients, aged 5 to 18 years, with blood samples collected at least one year after treatment completion. Of the 52 T-cell subpopulations analyzed, 16 showed statistically significant differences. Children after ALL treatment had lower absolute values of TCRγδ+ and higher values of double-positive CD4+CD8+ and CD8+ T cells. They also had higher absolute numbers of memory T cells, including total CD45RO+ T cells, and the CD45RO+CD8+ and CD45RO+CD27+ subpopulations. Furthermore, post treatment patients showed higher absolute values of activated T cells (HLA-DR+, HLA-DR+CD8+, HLA-DR+CD57+, and CD25+CD8+), as well as CD57+ and CCR7+ T cells. The absolute leukocyte and granulocyte counts were lower in the study group, while the total lymphocyte count was significantly higher compared to the control group. The findings indicate persistent changes in T-cell subpopulations after ALL treatment, suggesting ongoing immune system rebuilding and chronic antigenic stimulation, possibly due to viral reactivation or chemotherapy-related tissue damage. The increased number of TCRγδ+ cells, which are responsible for eliminating cancer cells, may be a positive aspect of this rebuilding.

Background: Multiparameter flow cytometry is widely used in the diagnosis of acute leukemia, allowing rapid identification of leukemic cells based on their immunophenotype. The EuroFlow Acute Leukemia Orientation Tube (ALOT) was designed as a standardized screening tool to support early diagnostic orientation and guide further, more targeted testing. In this study, we assessed the diagnostic performance of the ALOT panel in pediatric patients with suspected acute leukemia. Methods: A total of 254 pediatric patients (0–18 years) with suspected acute leukemia were analyzed. Bone marrow samples were assessed using multiparameter flow cytometry with the EuroFlow ALOT panel, comprising eight markers (MPO, cyCD79a, CD34, CD19, CD3, cyCD3, CD7, and CD45). Final diagnoses were established using extended immunophenotypic panels and additional diagnostic methods when required. Diagnostic performance was assessed by calculating sensitivity, specificity, precision, accuracy, and negative predictive value. Results: Among 254 patients, 234 were diagnosed with hematologic disorders, while 20 had normal bone marrow findings. The ALOT panel correctly identified all pathological samples and did not misclassify any normal sample, resulting in 100% sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for discrimination between abnormal and normal samples. In terms of exact diagnostic orientation, ALOT correctly classified 244 of 254 cases (96.1%) using a single-tube approach. The remaining 10 cases (3.9%), including rare entities such as Burkitt leukemia, chronic myeloid leukemia, and transient myeloproliferative syndrome, required extended immunophenotypic evaluation. Importantly, these cases were not false-negative results, as all were correctly identified as abnormal. Conclusions: The EuroFlow ALOT panel is a reliable screening tool for rapid diagnostic orientation in pediatric acute leukemia. Its implementation facilitates targeted selection of extended immunophenotypic panels, improving the efficiency and cost-effectiveness of diagnostic workflows.

Background: Multiparameter flow cytometry is widely used in the diagnosis of acute leukemia, allowing for rapid identification of leukemic cells based on their immunophenotype. The EuroFlow Acute Leukemia Orientation Tube was designed as a standardized screening tool to support early diagnostic orientation and guide further, more targeted testing. In this study, we assessed the diagnostic performance of the ALOT panel in pediatric patients with suspected acute leukemia. Methods: A total of 254 pediatric patients (0–18 years) with suspected acute leukemia were analyzed. Bone marrow samples were assessed using multiparameter flow cytometry with the EuroFlow ALOT panel, comprising eight markers (MPO, cyCD79a, CD34, CD19, CD3, cyCD3, CD7, and CD45). Final diagnoses were established using extended immunophenotypic panels and additional diagnostic methods when required. Samples were processed according to EuroFlow standard operating procedures and acquired on FACSCanto II and FACSCanto 10-color flow cytometers (BD Biosciences). Diagnostic performance was assessed by calculating sensitivity, specificity, precision, accuracy, and negative predictive value. Results: Among 254 patients, 234 were diagnosed with hematologic disorders, while 20 had normal bone marrow findings. The ALOT panel correctly identified all pathological samples and did not misclassify any normal sample, resulting in 100% sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for discrimination between abnormal and normal samples. In terms of exact diagnostic orientation, ALOT correctly classified 244 of 254 cases (96.1%) using a single-tube approach. The remaining 10 cases (3.9%), including rare entities such as Burkitt leukemia, chronic myeloid leukemia, and transient myeloproliferative syndrome, required extended immunophenotypic evaluation. Importantly, these cases were not false negative results, as all were correctly identified as abnormal. Conclusions: The EuroFlow ALOT panel is a reliable screening tool for rapid diagnostic orientation in pediatric acute leukemia. Its implementation facilitates targeted selection of extended immunophenotypic panels, improving the efficiency and cost-effectiveness of diagnostic workflows.