Diagnostic approaches to acute promyelocytic leukaemia

Typing of acute leukemia by intelligent optical time-stretch imaging flow cytometry on a chip

Acute leukemia (AL) is one of the top life-threatening diseases. Accurate typing of AL can significantly improve its prognosis. However, conventional methods for AL typing often require cell staining, which is time-consuming and labor-intensive. Furthermore, their performance is highly limited by the specificity and availability of fluorescent labels, which can hardly meet the requirements of AL typing in clinical settings. Here, we demonstrate AL typing by intelligent optical time-stretch (OTS) imaging flow cytometry on a microfluidic chip. Specifically, we employ OTS microscopy to capture the images of cells in clinical bone marrow samples with a spatial resolution of 780 nm at a high flowing speed of 1 m s^-1 in a label-free manner. Then, to show the clinical utility of our method for which the features of clinical samples are diverse, we design and construct a deep convolutional neural network (CNN) to analyze the cellular images and determine the AL type of each sample. We measure 30 clinical samples composed of 7 acute lymphoblastic leukemia (ALL) samples, 17 acute myelogenous leukemia (AML) samples, and 6 samples from healthy donors, resulting in a total of 227 620 images acquired. Results show that our method can distinguish ALL and AML with an accuracy of 95.03%, which, to the best of our knowledge, is a record in label-free AL typing. In addition to AL typing, we believe that the high throughput, high accuracy, and label-free operation of our method make it a potential solution for cell analysis in scientific research and clinical settings.

Leukemia diagnosis: today and tomorrow

The European LeukemiaNet (ELN) is composed of several work packages, four of them being directly involved in the various aspects of diagnosis. On the occasion of the annual ELN meeting of 2015 in Mannheim, these four work packages collectively examined the current situation and future prospects of cytomorphology, flow cytometry, cytogenetics, next-generation sequencing, and minimal residual disease detection in the context of leukemia diagnosis and follow-up. This document summarizes the outcome of this compendium.

Relevance of pathologic classifications and diagnosis of acute myeloid leukemia to clinical trials and clinical practice

Many new insights into the diagnosis, pathogenesis, clinical manifestation, treatment and prognosis of patients with AML reflect the heterogeneity of the disease. The initial descriptions of the various subtypes of AML, established by the FAB classification, were based on morphology and cytochemical stains. Although morphology remains the foundation for the diagnosis, additional diagnostic studies including immunophenotyping, cytogenetic evaluation, and molecular genetic studies have become critical, and in some specific cases, mandatory, complementary tools. Several specific subtypes of AML are now treated with directed or targeted therapy. Acute promyelocytic leukemia is currently the only example of a subtype of AML to which specific therapy targeted to a molecular genetic abnormality is available and this subtype now is highly curable. Future studies will address newly identified prognostic factors and gene mutations such as FLT3, Wilm's tumor (WTI), and CEBPA which will enable the further pathologic classification of patients with AML. Finally, microarray analysis will likely identify genes critically involved in the pathogenesis of specific pathologic subtypes.

Antigen expression patterns reflecting genotype of acute leukemias

Multi-parameter flow cytometry, molecular genetics, and cytogenetic studies have all contributed to new classification of leukemia. In this review we discuss immunophenotypic characteristics of major genotypic leukemia categories. We describe immunophenotype of: B-lineage ALL with MLL rearrangements, TEL/AML1, BCR/ABL, E2A/PBX1 translocations, hyperdiploidy, and myc fusion genes; T-ALL with SCL gene aberrations and t(5;14) translocation; and AML with AML1/ETO, PML/RARalpha, OTT/MAL and CBFbeta/MYH11 translocations, trisomies 8 or 11 and aberrations of chromosomes 7 and 5. Whereas some genotypes associate with certain immunophenotypic features, others can present with variable immunophenotype. Single molecules (as NG2, CBFbeta/SMMHC and PML/RARalpha proteins) associated with or derived from specific translocations have been described. More often, complex immunophenotype patterns have been related to the genotype categories. Most known associations between immunophenotype and genotype have been defined empirically. Therefore, these associations should be validated in independent patient cohorts before they can be widely used for prescreening of leukemia. Progress in our knowledge on leukemia will show how the molecular-genetic changes modulate the immunophenotype as well as how the expressed protein molecules further modulate cell behavior.