Light scatter characteristics of blast cells in acute myeloid leukaemia: association with morphology and immunophenotype

Fc gamma receptor expression serves as prognostic and diagnostic factor in AML

Risk assessment in acute myeloid leukemia (AML) mainly relies on (cyto-)genetic and morphologic features. Nonetheless, further markers are needed to allow for accurate risk stratification. Type I Fc gamma receptors (FcγRs) such as CD16, CD32, and CD64 play an important role in mediating immunomodulatory functions in different myeloid cell types as well as NK and B cells. We here evaluated expression of the three FcγR on peripheral blood AML blasts. Using flow cytometry, we found heterogeneous expression of the FcγR throughout the patient cohort. Correlation of expression levels with disease outcome revealed significantly shorter OS in patients with CD16⁺ blasts at first diagnosis. CD32 and CD64 expression showed no association with survival but correlated with a mature phenotype and FAB M6. Our data provide clear evidence for the value of immunophenotyping FcγR expression on leukemic cells using peripheral blood, which is rapidly available and improves risk stratification in AML.

Aurora A and NF-κB Survival Pathway Drive Chemoresistance in Acute Myeloid Leukemia via the TRAF-Interacting Protein TIFA

Aurora A-dependent NF-κB signaling portends poor prognosis in acute myeloid leukemia (AML) and other cancers, but the functional basis underlying this association is unclear. Here, we report that Aurora A is essential for Thr9 phosphorylation of the TRAF-interacting protein TIFA, triggering activation of the NF-κB survival pathway in AML. TIFA protein was overexpressed concurrently with Aurora A and NF-κB signaling factors in patients with de novo AML relative to healthy individuals and also correlated with poor prognosis. Silencing TIFA in AML lines and primary patient cells decreased leukemic cell growth and chemoresistance via downregulation of prosurvival factors Bcl-2 and Bcl-X_L that support NF-κB-dependent antiapoptotic events. Inhibiting TIFA perturbed leukemic cytokine secretion and reduced the IC₅₀ of chemotherapeutic drug treatments in AML cells. Furthermore, in vivo delivery of TIFA-inhibitory fragments potentiated the clearance of myeloblasts in the bone marrow of xenograft-recipient mice via enhanced chemotoxicity. Collectively, our results showed that TIFA supports AML progression and that its targeting can enhance the efficacy of AML treatments. Cancer Res; 77(2); 494-508. ©2016 AACR.

CD45RA, a specific marker for leukaemia stem cell sub-populations in acute myeloid leukaemia

Chemotherapy resistant leukaemic stem cells (LSC) are thought to be responsible for relapses after therapy in acute myeloid leukaemia (AML). Flow cytometry can discriminate CD34(+) CD38(-) LSC and normal haematopoietic stem cells (HSC) by using aberrant expression of markers and scatter properties. However, not all LSC can be identified using currently available markers, so new markers are needed. CD45RA is expressed on leukaemic cells in the majority of AML patients. We investigated the potency of CD45RA to specifically identify LSC and HSC and improve LSC quantification. Compared to our best other markers (CLL-1, also termed CLEC12A, CD33 and CD123), CD45RA was the most reliable marker. Patients with high percentages (>90%) of CD45RA on CD34(+) CD38(-) LSC have 1·69-fold higher scatter values compared to HSC (P < 0·001), indicating a more mature CD34(+) CD38(-) phenotype. Patients with low (<10%) or intermediate (10-90%) CD45RA expression on LSC showed no significant differences to HSC (1·12- and 1·15-fold higher, P = 0·31 and P = 0·44, respectively). CD45RA-positive LSC tended to represent more favourable cytogenetic/molecular markers. In conclusion, CD45RA contributes to more accurate LSC detection and is recommended for inclusion in stem cell tracking panels. CD45RA may contribute to define new LSC-specific therapies and to monitor effects of anti-LSC treatment.

B-cell acute lymphoblastic leukemia with t(4;11)(q21;q23) in a young woman: evolution into mixed phenotype acute leukemia with additional chromosomal aberrations in the course of therapy

About 5% of adult B-cell acute lymphoblastic leukemias (B-ALL) are characterized by t(4;11)(q21;q23), which confers peculiar features to this B-ALL subtype, including a very immature immunophenotype and poor prognosis. We describe the case of a 21-year-old female who presented with B-ALL carrying the t(4;11)(q21;q23) and blasts positive for CD19, TdT, CD79a, CD38, HLA-DR. Before completing the Hyper-CVAD (hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone) therapy regimen, the B-cell leukemic clone still was detected, but an additional leukemic clone appeared, with morphology and immunophenotype (CD13, CD33, CD64, CD38, CD56, CD15, CD4(dim)) compatible with derivation from the myeloid/monocytic lineage. Karyotype showed the co-existence of three cell lines, with persistence of t(4;11)(q21;q23) and appearance of +8,+12,+13 and two der(4). The patient died because of disseminated intravascular coagulation. Our report describes a rare, possible evolution of such a subtype of B-ALL, with transformation into mixed phenotype acute leukemia in the course of therapy. This finding suggests a blast cell derivation from a common lymphoid/monocytic precursor leading to a final bilineal acute leukemia.

Cell markers and the side population phenotype in ocular surface epithelial stem cell characterization and isolation

The ocular surface is covered by tworapidly renewing and embryologically-related linings, the corneal and conjunctival epithelia. The long-term survival of thesetissues is ultimately dependent on their respective resident stem cells. In the corneal epithelium, the stem cells and their early precursors are exclusively circumscribed to the narrow vasscularize limbal rim that provides epithelial precursor cells to the critically transparent central cornea. Limbal damage causes an interruption of this essential cell supply and allows the invasion of the corneal surface by the conjunctival epithelium, an event that ultimately leads to corneal scarring. The limited supply of immunocompatible tissue is a major hindrance to efforts to develop effective procedures for ocular surface reconstruction. This review describes some of the current work and strategies being developed to achieve the isolation of the limbal stem cell and define its genetic, biochemical, and functional make-up. The study of isolated ocular surface stem cells will foster basic understanding of the environmentalrequisites for their survival and proliferation in a self-replicative mode, leading eventually to advances in therapeutic approaches.

Use of the Cell-Dyn 3500 to predict leukemic cell lineage in peripheral blood of dogs and cats

BACKGROUND

Morphology and cytochemistry are the foundation for classification of leukemias in dogs and cats. Advances in automated hematology instrumentation, immunophenotyping, cytogenetics, and molecular biology are significantly improving our ability to recognize and classify spontaneous myeloproliferative and lymphoproliferative disorders.

OBJECTIVE

The purpose of this study was to assess the utility of flow cytometry-based light scatter patterns provided by the Cell-Dyn 3500 (CD3500) automated hematology analyzer to predict the lineage of leukemic cells in peripheral blood of dogs and cats.

METHODS

Leukemic cells from 15 dogs and 6 cats were provisionally classified using an algorithm based on the CD3500 CBC output data and were subsequently phenotyped by enzyme cytochemistry, immunocytochemistry, indirect flow cytometry, and analysis of antigen receptor gene rearrangement.

RESULTS

The algorithm led to correct predictions regarding the ontogeny of the leukemic cells (erythroid/megakaryocytic potential, myeloid leukemia, monocytic leukemia, chronic granulocytic leukemia, lymphoid leukemia) in 19/21 animals. Mismatches in the WBC impedance count and the WBC optical count in conjunction with microscopic assessment of blasts in the blood were useful for predicting myeloproliferative disorders with erythroid or megakaryocytic potential. The leukocyte light scatter patterns enabled distinction among myeloid leukemias (represented by acute myelomonocytic leukemia, acute monocytic leukemia, chronic granulocytic leukemia) and lymphocytic leukemias (including acute and chronic lymphocytic leukemias). One case of acute lymphocytic leukemia was misidentified as chronic lymphocytic leukemia.

CONCLUSIONS

Algorithmic analyses can be applied to data generated by the CD3500 to predict the ontogeny of leukemic cells in the peripheral blood of dogs and cats. This rapid and quantitative technique may be used to improve diagnostic decisions, expand therapeutic choices, and increase prognostic accuracy.

The importance of cell size and surface marker analysis in childhood acute myeloblastic leukemia

In order to evaluate the prognostic significance of cell size and surface marker expression, we evaluated 33 children with newly diagnosed acute myeloblastic leukemia by flow cytometry. We determined: the percentage of small, middle and large cells; large to small cell ratios (LS); large plus middle to small cell ratios (LMS); the percentage of surface markers expressed by each group of cell; the ratios of surface marker percentages expressed by the large blasts to that expressed by small blasts (LS for surface markers); and large plus middle blasts to that by small blasts (LMS for surface markers). For 'early prognosis', patients who could and could not achieve remission (n = 23 and 10) and for late prognosis, the patients who deceased or relapsed within the first 12 months of the treatment (n = 24) and who survived for more than 12 months (n = 9) were compared, in two classifications. CD3 percentages of the small cells of alive patients were significantly higher than that of dead or relapsed patients. LMS for CD3 and CD20 and LS for CD20 were higher in dead relapsed patients than that of alive patients. The total percentage of CD14 was significantly higher in dead relapsed patients than it was in the alive patients and CD3 was significantly higher in the group of patients who achieved remission than that of the patients who could not achieve remission. It was striking that, expression of CD3, CD7, CD22, CD33, CD14, CD15, CD34 increased or decreased as to cell size, whatever the prognosis. CD10, CD20 and CD13 were expressed on the large cells of the patients who could not achieve remission or died relapsed. We showed that, the blast cell size, individually does not have any prognostic significance in childhood AML and the prognostic significance of surface markers not only depends on their presence or absence but also on their relative configuration of expression by the blasts with different size.