Acute biphenotypic leukaemia: immunophenotypic and cytogenetic analysis

The incidence of acute biphenotypic leukaemia has ranged from less than 1% to almost 50% in various reports in the literature. This wide variability may be attributed to a number of reasons including lack of consistent diagnostic criteria, use of various panels of antibodies, and the failure to recognize the lack of lineage specificity of some of the antibodies used. The morphology, cytochemistry, immunophenotype and cytogenetics of acute biphenotypic leukaemias from our institution were studied. The diagnostic criteria took into consideration the morphology of the analysed cells, light scatter characteristics, and evaluation of antibody fluorescence histograms in determining whether the aberrant marker expression was arising from leukaemic blasts or differentiated bone marrow elements. Fifty-two of 746 cases (7%) fulfilled our criteria for acute biphenotypic leukaemias. These included 30 cases of acute lymphoblastic leukaemia (ALL) expressing myeloid antigens, 21 cases of acute myelogenous leukaemia (AML) expressing lymphoid markers, and one case of ALL expressing both B- and T-cell associated antigens. The acute biphenotypic leukaemia cases consisted of four major immunophenotypic subgroups: CD2± AML (11), CD19± AML (8), CD13 and/or CD33± ALL (24), CD11b± ALL (5) and others (4). Chromosomal analysis was carried out in 42/52 of the acute biphenotypic leukaemia cases; a clonal abnormality was found in 31 of these 42 cases. This study highlights the problems encountered in the diagnosis of acute biphenotypic leukaemia, some of which may be reponsible for the wide variation in the reported incidence of this leukaemia. We suggest that the use of strict, uniform diagnostic criteria may help in establishing a more consistent approach towards diagnosis of this leukaemic entity. We also suggest that biphenotypic leukaemia is comprised of biologically different groups of leukaemia based on immunophenotypic and cytogenetic findings.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73301/1/j.1365-2141.1993.tb03024.x.pd

Further investigations on the expression of HLA-DR, CD33 and CD13 surface antigens in purified bone marrow and peripheral blood CD34+ haematopoietic progenitor cells.

We evaluated the HLA-DR, CD33 and CD13 antigen expression on CD34+ haematopoietic progenitor cells (HPC) isolated from the bone marrow (BM) and peripheral blood (PB) of normal donors. The majority of both BM and PB CD34+ HPC expressed CD13 and HLA-DR. The coexpression of CD34 and CD33 was found in a minor CD34+ subset. After 7 d of culture in the presence of interleukin-3 and granulocyte-macrophage colony-stimulating factor, CD33 expression was detected in about 50\% of HPC. At this point CD34 antigen expression was lost and CD13 and HLA-DR expression was partially lost. After 14 d of culture, the majority of HPC were CD33+. HPC maintained the capacity to generate colony forming unit granulocyte-macrophage but they lost the capacity to generate burst forming unit-erythroid. A correlation was found between the percentage of CD34+/HLA-DR+ cells and the total number of colony forming cells in unfractionated samples from BM and PB of patients with malignancies. These studies demonstrate that, in normal conditions, only a minor subset of CD34+ cells coexpress CD33 antigen either in BM or in PB and CD33 antigen is a lineage marker which is coexpressed with HLA-DR and CD13 on a progenitor committed to the granulocytic-macrophagic lineage