Immunophenotype of blast cells in chronic myeloid leukemia

CD7 expression on CD34+ cells from chronic myeloid leukaemia in chronic phase

Thirty-seven patients with chronic phase chronic myeloid leukaemia and fourteen healthy controls have been evaluated for lineage differentiation with immunological markers on purified bone marrow CD34 positive cells by multiparameter flow cytometry. The myeloid-associated antigen CD33 and the stem cell factor receptor (CD117, c-kit) was expressed by 82.3% and 73.5% on CP-CML patients and by 57% and 57.5% on healthy donors, respectively (P < 0.005). CD34+/CD19+ or CD34+/CD10+ B-lymphoid cell population represented 9. 1% and 10.7% of the CD34+ cells in CML whereas in normal controls this subpopulation was expressed by 27.9% and 30.4% of the CD34+ cells, respectively (P< 0.005). The T-lineage associated markers (CD7 and CD2) were detected on a minor population of CD34+ BM cells of healthy controls (mean, 3.6% and 4.6%, respectively). The CD2 positive cells represented 1.5% of the CD34+ cells in CML patients. CP-CML patients co-expressed the CD7 antigen on a mean of 32.6% of the CD34+ BM cells. Moreover, 93% of this CD34/CD7 double positive subpopulation co-expressed CD33 antigen in CML patients. Co-expression of CD7 on CD34+ cells was induced to decrease significantly after short-term in vitro culture with the differentiation-inducing agent phorbol ester (PMA) and with a combination of cytokines (stem-cell factor, interleukin-3 and granulocyte colony-stimulating factor). In conclusion, a high co-expression of CD7 antigen is demonstrated on CD34+ cells of chronic phase-chronic myeloid leukaemia patients. The loss of CD7 marker following incubation with PMA and cytokines suggests that this antigen is expressed transiently in early myeloid leukaemic CML haemopoiesis.

Identification of homeobox-containing genes expressed in hematopoietic blast cells

Among putative candidates involved in commitment and differentiation of hematopoietic cells are homeoproteins, a large family of transcription factors playing a major role during development. Using a polymerase chain reaction (PCR)-derived protocol, we have investigated for Antennapedia-like homeobox-containing (HOX) gene expression in an enriched population of human hematopoietic progenitors. Nine members of HOX 1 and HOX 2 loci were isolated. Together with recent studies using established cell lines, this indicates a large representation of HOX genes in the hematopoietic compartment and suggests a participation of this class of nuclear proteins to early steps of hematopoiesis.

Isolation and characterization of the CD34+ hematopoietic progenitor cells from the peripheral blood of patients with chronic myeloid leukemia

A modified version of the original reported panning technique was used to separate CD34+ cells from the peripheral blood of patients with chronic myeloid leukemia (CML). In 13 out of 23 separations, populations of cells were obtained in which CD34+ cells constituted greater than 50% of the cells present. The best recovery and enrichment of the CD34+ cells was achieved when cells were obtained from patients in the accelerated phase of CML, when the cells were processed on the same day they were obtained from patients, and when adherence to soybean agglutinin flasks was used as a pre-enrichment step. In suspension culture, the CD34+ cells were capable of extensive proliferation and differentiation. In semi-solid culture, the number of colony-forming units (CFUs) directly correlated with CD34 positivity. The number of clonogenic cells/CD34+ cells was highest at the time of initial diagnosis of CML, fell during the chronic phase (CP) of the disease, and rose at the time of disease acceleration. This observation suggests that therapy during the CP of the disease produces a greater reduction in clonogenic cells than in the number of CD34+ cells. This effect disappears at the time of disease acceleration, presumably because of the development of drug resistance in the clonogenic cells.

p53 in chronic myelogenous leukemia in acute phase

All patients with chronic myelogenous leukemia (CML) undergo clinical transition from chronic to acute phase. This transition is often associated with deletion of the short arm of chromosome 17 in the form of the i(17q) aberration. Since the p53 gene is a suppressor gene and is located on 17p13, we examined the possibility that it is inactivated during progression of CML. Therefore, we studied the structure and expression of p53 in the leukemic cells of a large number of CML patients in acute phase. We found that although the gene is rarely rearranged, one p53 allele is completely deleted in patients with the i(17q) aberration as well as in some patients who do not show karyotypic changes. In all of these patients the remaining allele is inactivated through loss of expression, rearrangement, or point mutation. Detailed analysis of some patients who carry both p53 alleles indicated neither loss of expression nor structural alterations. It appears that p53 loss of function is associated with progression of around 25% of CML patients.

Expression of hematopoietic progenitor cell associated antigen CD34 in chronic myeloid leukemia

The expression of progenitor cell associated antigen CD34 was investigated in cells from 28 patients with chronic myeloid leukemia (CML). The CD34 positivity varied from 0-26% in patients with chronic phases CML (n = 17); from 6-64% in patients with accelerated phase CML (n = 4); and from 27-97% in the patients with blastic crisis of CML (n = 8). The difference in CD34 positivity between chronic (mean 10.1 +/- 2.3%), accelerated (37.7 +/- 13.3%) and blastic (58.0 +/- 7.3%) phases of CML is statistically significant (p less than 0.05), however, the number of patients studied, especially in accelerated and blastic phases is very small. There was no difference in the CD34 positivity of the cells in the peripheral blood and in the bone marrow. CD34 positivity was higher in patients with chronic phase CML at diagnosis (untreated patients) than in those who were studied during treatment. The possible importance of serially studying CD34 positivity in patients with CML is discussed in the paper.

Chronic myeloproliferative disorders in bone marrow biopsies

This Diagnostic Seminar intends to announce that CMPDs can be classified from BMB histologically by a rather simple system, which can be applied by interested histopathologists successfully. The rationale of this classification is to stay within the groups of diseases which are outlined by clinical findings including the peripheral blood and bone marrow smears. The concept of traditional classification as given by the WHO and textbooks, however, has to be revised as follows (1) Primary diseases of CMPDs must be distinguished from advanced disorders. Primary diseases are CML, P. vera, Thrombocythemia, CMGM, and unclassifiable CMPD. (2) Idiopathic, primary myelosclerosis of the bone marrow is a reactive feature consecutive to neoplastic transformation of hematopoiesis, i.e. myeloproliferation. (3) Advanced disorders comprise (3.1.) excess of blasts and blast crisis, and (3.2.) early myelosclerosis, myelosclerosis and myelofibrosis, advanced myelofibrosis. Advanced disorders are designated by a composed term classifying them among the groups of primary disease and specifying the advanced stage by a suffix, so that the underlying disease remains coining the term, even in unclassifiable cases in which only CMPDs can be applied. (4) The CML group must be subtyped into CML of common type versus that with increase or predominance of megakaryocytes. By this system of classification, it seems possible to classify and type the spectrum of variations occurring among CMPDs to a satisfying result.

Susceptibility of autologous target cells to lysis by lymphokine-activated effectors from interferon-alpha-treated chronic myelogenous leukaemia patients

Chronic myelogenous leukemia (CML) patients in chronic phase display compromised lymphokine-activated killer (LAK) cell induction, which is partly restored after therapy with interferon alpha. However, the relative resistance of the leukemic cells from these patients to autologous or allogeneic LAK lysis is not affected by this treatment. In an attempt to render CML cells more susceptible to lysis or cytostasis, they were precultured in serum-free medium with or without recombinant growth factors. In eight patients studied, interleukin-3 (IL-3) significantly enhanced the spontaneous short-term (6-day) proliferation of CML cells, with retention of ability to form colonies in methylcellulose. Culture in either medium alone or IL-3 led to a significant enrichment of CD14+ and CD33+ cells but to a reduction in CD34+ cells. In contrast, culture of the same cells in IL-2 (to generate autologous LAK activity) resulted in a loss of CD14+ and CD33+ as well as CD34+ cells but in a significant increase in CD3+ and CD56+ cells. Despite similarities in their phenotypes, IL-3 cultured cells but not those cultured in medium alone acquired susceptibility to lysis by the IL-2-cultured autologous LAK cells. These results may have significance for the design of novel combination immunotherapy in CML.