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Robert D Sutherland - One of the best experts on this subject based on the ideXlab platform.

  • the ishage guidelines for CD34 cell determination by flow cytometry international society of hematotherapy and graft engineering
    Journal of hematotherapy, 1996
    Co-Authors: Robert D Sutherland, Lori Anderson, Michael Keeney, Rakash Nayar, Ian Chinyee
    Abstract:

    The increased use of Peripheral Blood Stem Cells (PBSC) to reconstitute hematopoiesis in autotransplant and, more recently, allotransplant settings has not been associated with a consensus means to quality control the PBSC product. Since the small population of cells that bear the CD34 Antigen are thought to be responsible for multilineage engraftment, graft assessment by flow cytometric quantitation of CD34+ cells should provide a rapid, reliable, and reproducible assay. Unfortunately, although a number of flow cytometric assays for CD34 enumeration have been described, the lack of a standardized method has led to the generation of widely divergent data. Furthermore, none of these assays has been validated as to interlaboratory reproducibility and suitability for widespread clinical application. In early 1995, the International Society of Hematotherapy and Graft Engineering (ISHAGE) established a Stem Cell Enumeration Committee, the mandate of which was to validate a simple, rapid, and sensitive flow cytometric method to quantitate CD34+ cells in peripheral blood and apheresis products. We also sought to establish its utility on a variety of flow cytometers in clinical laboratories and its reproducibility between transplant centers. Here, we describe the four-parameter flow methodology adopted by ISHAGE for validation in a multicenter study in North America.

  • CD34 Antigen molecular features and potential clinical applications
    Stem Cells, 1993
    Co-Authors: Robert D Sutherland, Keith A Stewart, Armand Keating
    Abstract:

    Despite the wide variety of functions exhibited by mature peripheral blood cells, all are derived from a small pool (1-3%) of primitive precursor cells in the bone marrow (BM) that bear a unique surface glycoprotein, CD34. Isolated CD34+ cells are capable of reconstituting all hematopoietic lineages, both in experimental animals and in humans following intensive therapy. CD34+ cells capable of reconstituting hematopoiesis are also found at low frequency in peripheral blood (PB), a frequency which can be dramatically increased by combinations of chemotherapy and recombinant cytokines. In some cases, PB "stem cells" (PBSC) can be used to augment or even replace conventional BM autografts. The availability of CD34 antibodies has greatly aided the development of techniques for the enrichment of primitive progenitor cells, thus allowing studies of the hematopoietic potential of stem cells in vitro. Additionally, the use of CD34 antibodies for the "positive selection" of hematopoietic stem/progenitor cells from tumor-contaminated marrow may possibly represent an alternative "purging" strategy prior to transplantation. The availability of pure populations of the most primitive hematopoietic progenitor cells will also facilitate study of genetic manipulation as a practical therapeutic modality.

  • activated protein kinase c directly phosphorylates the CD34 Antigen in acute lymphoblastic leukemia cells
    Leukemia & Lymphoma, 1992
    Co-Authors: Robert D Sutherland, Mary Jo Fackler, Stratford W May, Kathryn E Matthews, Michael Baker
    Abstract:

    The precursors of all blood cell lineages are contained within the 1–3% of bone marrow cells which express the CD34 Antigen and this population can reconstitute the hematopoietic system of lethally irradiated animals and humans. A potential regulatory role for the CD34 Antigen in progenitor cell function and differentiation was indicated by our recent findings that the CD34 Antigen can be phosphorylated in vivo to high stoichiometry in primitive CD34 + cell-lines by activated protein kinase C. To exclude the possibility that these effects were restricted to cell-lines, we have performed similar experiments on fresh cells from a patient with drug-resistant acute lymphoblastic leukemia. Similar to our previous findings, we found the CD34 Antigen to be hyperphosphorylated in lymphoblasts labeled in the presence of active phorbols. The same peptides which were hyperphosphorylated in phorbol-stimulated cell-lines were also phosphorylated in phorbol-stimulated lymphoblasts. These data indicate that CD34 is a su...

  • the CD34 Antigen structure biology and potential clinical applications
    Journal of hematotherapy, 1992
    Co-Authors: Robert D Sutherland, Armand Keating
    Abstract:

    The diversity of function of mature circulating blood cells is reflected in their respective complements of cell-surface molecules and receptors. Although monoclonal antibodies have been instrumental in the identification and characterization of many cell-surface molecules on mature hematopoietic cells, the CD34 Antigen represents to date, the only molecule, similarly identified, whose expression within the blood system is restricted to a small number of primitive progenitor cells in the bone marrow. Although its precise function remains unknown, the pattern of expression of the CD34 structure suggests that it plays an important role in early hematopoiesis. The availability of CD34 antibodies has greatly aided the development of techniques for the enrichment of primitive progenitor cells for studies of hematopoiesis in vitro. Additionally, the use of CD34 antibodies for the 'positive selection' of hematopoietic stem/progenitor cells represents and alternative strategy to 'negative selection' or purging for the large-scale manipulation of bone marrow cells prior to transplantation. The availability of pure populations of the most primitive hematopoietic progenitor cells may also facilitate the development of genetic techniques for the repair of specific blood cell disorders. In this article, we review the biology of the CD34 molecule and assess some of the roles for CD34 antibodies in immunopathology and for progenitor/stem cell purification in clinical applications.

Armand Keating - One of the best experts on this subject based on the ideXlab platform.

  • CD34 Antigen molecular features and potential clinical applications
    Stem Cells, 1993
    Co-Authors: Robert D Sutherland, Keith A Stewart, Armand Keating
    Abstract:

    Despite the wide variety of functions exhibited by mature peripheral blood cells, all are derived from a small pool (1-3%) of primitive precursor cells in the bone marrow (BM) that bear a unique surface glycoprotein, CD34. Isolated CD34+ cells are capable of reconstituting all hematopoietic lineages, both in experimental animals and in humans following intensive therapy. CD34+ cells capable of reconstituting hematopoiesis are also found at low frequency in peripheral blood (PB), a frequency which can be dramatically increased by combinations of chemotherapy and recombinant cytokines. In some cases, PB "stem cells" (PBSC) can be used to augment or even replace conventional BM autografts. The availability of CD34 antibodies has greatly aided the development of techniques for the enrichment of primitive progenitor cells, thus allowing studies of the hematopoietic potential of stem cells in vitro. Additionally, the use of CD34 antibodies for the "positive selection" of hematopoietic stem/progenitor cells from tumor-contaminated marrow may possibly represent an alternative "purging" strategy prior to transplantation. The availability of pure populations of the most primitive hematopoietic progenitor cells will also facilitate study of genetic manipulation as a practical therapeutic modality.

  • the CD34 Antigen structure biology and potential clinical applications
    Journal of hematotherapy, 1992
    Co-Authors: Robert D Sutherland, Armand Keating
    Abstract:

    The diversity of function of mature circulating blood cells is reflected in their respective complements of cell-surface molecules and receptors. Although monoclonal antibodies have been instrumental in the identification and characterization of many cell-surface molecules on mature hematopoietic cells, the CD34 Antigen represents to date, the only molecule, similarly identified, whose expression within the blood system is restricted to a small number of primitive progenitor cells in the bone marrow. Although its precise function remains unknown, the pattern of expression of the CD34 structure suggests that it plays an important role in early hematopoiesis. The availability of CD34 antibodies has greatly aided the development of techniques for the enrichment of primitive progenitor cells for studies of hematopoiesis in vitro. Additionally, the use of CD34 antibodies for the 'positive selection' of hematopoietic stem/progenitor cells represents and alternative strategy to 'negative selection' or purging for the large-scale manipulation of bone marrow cells prior to transplantation. The availability of pure populations of the most primitive hematopoietic progenitor cells may also facilitate the development of genetic techniques for the repair of specific blood cell disorders. In this article, we review the biology of the CD34 molecule and assess some of the roles for CD34 antibodies in immunopathology and for progenitor/stem cell purification in clinical applications.

Nigel H Russell - One of the best experts on this subject based on the ideXlab platform.

  • bcl 2 expression in acute myeloblastic leukaemia relationship with autonomous growth and CD34 Antigen expression
    Leukemia & Lymphoma, 1997
    Co-Authors: D Bradbury, Y M Zhu, Nigel H Russell
    Abstract:

    The bcl-2 gene encodes a mitochondrial protein that inhibits the onset of apoptosis induced by growth factor withdrawal or cytotoxic agents. Using quantitative flow cytometry and expressing bcl-2 levels as the number of molecules of equivalent soluble fluorochrome (MESF) per cell, we have shown that bcl-2 protein expression in the blast cells from patients with acute myeloblastic leukaemia (AML) is heterogeneous, but not related to FAB type. The blast cells from AML patients with the capacity to grow and survive autonomously in vitro were found to have higher bcl-2 MESF values than those that were dependent upon exogenous growth factors. We have previously reported that the blast cells from 70% of AML patients exhibit autonomous growth and autocrine growth factor production in vitro and that this has been shown to be an important indicator of poor prognosis in AML. High bcl-2 expression has also been associated with a low complete remission rate and poor survival in AML. In the patients whose blast cells exhibited autonomous growth, neutralisation of endogenous GM-CSF resulted in down-regulation of bcl-2 protein, whereas in blast cells from patients whose cells proliferated only in the presence of added growth factors, incorporation of recombinant human (rh) GM-CSF in the culture media resulted in up-regulation of bcl-2. Because CD34 positivity has been reported as another indicator of poor prognosis in AML, we compared bcl-2 expression in cases of CD34 positive AML, CD34 negative AML and CD34 positive normal bone marrow cells. Bcl-2 was found to be strongly expressed on the CD34+ normal bone marrow cells. The blast cells from CD34+ AML patients expressed significantly higher bcl-2 levels than CD34- AML patients. In five cases of CD34+ AML, the bcl-2 levels were determined on purified CD34+ and CD34- blast cell populations. The CD34+ blast cells were found to express significantly higher bcl-2 levels compared with the CD34-blast cells. Our data would suggest that quantification of bcl-2 in AML blast cell may be useful as a prognostic indicator in AML.

  • down regulation of bcl 2 in aml blasts by all trans retinoic acid and its relationship to CD34 Antigen expression
    British Journal of Haematology, 1996
    Co-Authors: D A Bradbury, Y M Zhu, S Aldington, Nigel H Russell
    Abstract:

    High levels of expression of the bcl-2 oncoprotein in acute myeloblastic leukaemia (AML) cells have been associated with low complete remission rates and poor survival. The sensitivity of AML blasts to drugs such as Ara-C can be increased by the down-regulation of bcl-2 expression by antisense oligonucleotides. All-trans retinoic acid (ATRA) has been reported to increase the sensitivity of AML cell lines to Ara-C and to induce differentiation in the HL60 promyelocytic cell line, with both effects being accompanied by a decrease in bcl-2 expression. Using flow cytometry and a monoclonal antibody to bcl-2, we have investigated the effects of ATRA (1 microM) on bcl-2 expression in the blast cells of 25 AML patients and the K562 cell line after incubation for 72 or 24 h, respectively. Using Kolmogorov-Smirnov statistical analysis where a D value of > 0.12 was statistically significant, we found that in 8/25 AML samples and the K562 cells there was a significant decrease in bcl-2 protein expression after incubation with ATRA (D value range 0.14-0.44). The mean peak fluorescence (MPF) values for the bcl-2 levels of the ATRA responders (n = 8) was reduced to 35.5 +/- 6.9 following incubation with ATRA compared to 47.6 +/- 8.2 (mean +/- SEM) for control samples incubated in the absence of ATRA (P = 0.014). There was no significant difference between the baseline bcl-2 molecules of equivalent soluble fluorochrome (MESF) levels in the ATRA responders (48.9 +/- 5.7, n = 8) and the non-responders (41.3 +/- 3.9, n = 17) (mean +/- SEM) (P = 0.28). The down-regulation of bcl-2 expression by ATRA was particularly associated with CD34-negative AML and of the eight AML patients' cells that responded to ATRA by down-regulating bcl-2, seven were CD34 negative (P < 0.05). Our data suggest that the addition of ATRA to combination chemotherapy would increase the chemosensitivity of some patients with AML, particularly CD34-negative AML, due to down-regulation of bcl-2 expression.

Xiong Ni - One of the best experts on this subject based on the ideXlab platform.

  • clinical and biological characteristics of adult biphenotypic acute leukemia in comparison with that of acute myeloid leukemia and acute lymphoblastic leukemia a case series of a chinese population
    Haematologica, 2009
    Co-Authors: Xiaoqian Xu, Jianmin Wang, Shuqing Lu, Li Chen, Jianmin Yang, Weiping Zhang, Xianmin Song, Xiong Ni
    Abstract:

    BACKGROUND: Biphenotypic acute leukemia is a rare disorder that is difficult to diagnose. It displays features of both myeloid and lymphoid lineage. There is still a lack of studies in biphenotypic acute leukemia in a Chinese population. We present here a comprehensive investigation of the clinical and biological characteristics, and outcome of biphenotypic acute leukemia in our hospital in over a seven year period. DESIGN AND METHODS: We retrospectively analyzed 452 adult acute leukemia patients diagnosed according to French-American-British (FAB) classification and biphenotypic acute leukemia diagnosed according to European Group for the Immunological Characterization of Leukemias (EGIL) classification, respectively. Biological characteristics, response to treatment, and outcome were examined in biphenotypic acute leukemia patients and compared with that in acute myeloid leukemia and acute lymphoblastic leukemia patients with complete follow-up profiles diagnosed in the same period. RESULTS: Of 452 acute leukemia patients, 21 cases (4.6%) were diagnosed as biphenotypic acute leukemia. Among them, 14 (66.7%) were B lymphoid and myeloid, 5 (23.8%) were T lymphoid and myeloid, one (4.8%) was T/B lymphoid and one (4.8%) was trilineage differentiation. When compared with acute myeloid leukemia and acute lymphoblastic leukemia, patients with biphenotypic acute leukemia showed significantly higher incidence of CD34 Antigen expression, unfavorable karyotypes, and extramedullary infiltration (p<0.05). In this cohort of patients with biphenotypic acute leukemia, t(9;22) was the most common abnormality in chromosome structure. The median disease-free survival and overall survival in biphenotypic acute leukemia patients was five months and ten months, respectively, significantly shorter than those in acute myeloid leukemia and acute lymphoblastic leukemia patients (p<0.05). CONCLUSIONS: The prognosis of biphenotypic acute leukemia patients is poor when compared with de novo acute myeloid leukemia or acute lymphoblastic leukemia. Biphenotypic acute leukemia patients showed a much higher incidence of CD34 Antigen expression, complex abnormal karyotype, extramedullary infiltration, relapse, and resistance to therapy after relapse.

N P Lucie - One of the best experts on this subject based on the ideXlab platform.

  • the prognostic significance of the CD34 Antigen in acute myeloid leukaemia
    Leukemia & Lymphoma, 1992
    Co-Authors: H Myint, N P Lucie
    Abstract:

    The prognostic value of CD34 expression on leukaemic blast cells was assessed in 38 patients with acute myeloid leukaemia. Nineteen patients had more than 10% CD34 positive blast cells. Median survival for the CD34 positive patients was 125 days and for the CD34 negative patients the median survival has not yet been reached at day 575 (p = 0.06). Of those patients who received intensive chemotherapy, CD34 positive patients (n = 13) had a median survival of 150 days while for CD34 negative patients (n = 14) the median survival has not yet been reached (p = 0.01). Adjustment for age and pre-existing myelodysplastic syndrome did not affect the correlation of CD34 positivity with survival (p = 0.02). Over the period of observation (median 10 months, range 2-19 months) the relative risk of death was 5 times greater for the CD34 positive patients. This study suggests that CD34 expression is an adverse prognostic marker, independent of age and pre-existing myelodysplasia.