First-line diagnosis based on immunological phenotyping in suspected acute leukemia: a prospective study

FAB M4 and high CD14 surface expression is associated with high cellular resistance to Ara-C and daunorubicin: implications for clinical outcome in acute myeloid leukaemia

In 145 adult patients diagnosed with non-M3 acute myeloid leukaemia (AML) the relevance of FAB-subtype and immunophenotype to in vitro cellular drug resistance towards the anthracyclines aclarubicin (Acla) and daunorubicin (Dau), and the nucleoside analogue cytarabine (Ara-C), as well as other antileukaemic drugs, was investigated using a 4-d MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) assay. We demonstrate that high CD14 expression is highly significantly associated with high cellular Ara-C and Dau resistance in univariate as well as multivariate analyses. FAB subtypes with highest and lowest cellular Ara-C resistance were M4 and M5, respectively (P < 0.01, one-way anova), whereas FAB subtypes with highest and lowest cellular Dau resistance were M4 and M1, respectively (P < 0.01, one-way anova). By contrast, no significant differences in cellular drug resistance towards Acla could be demonstrated among FAB subtypes. Furthermore, in two cohorts of AML patients treated by two different regimens for remission induction over a period of 15 yr (1985-94, n = 159 and 1995-99, n = 76, respectively) we demonstrate in univariate analyses a significance of CD14 expression with respect to clinical outcome. With the exception of significance to probability of obtaining complete remission in the first cohort (P = 0.03, logistic regression), this significance was, however, lost in multivariate analyses. It was demonstrated that FAB-M4 patients were older than M5 patients and that high CD14 expression was associated with the presence of secondary AML and older age. We conclude that although cases with high blast cell CD14 expression (and FAB-M4 cases) were more resistant to Ara-C as well as Dau in vitro, the clinical and biological significance of this may be debatable because of interactions with major prognostic factors in AML.

Identification of acute myeloid leukemia patients with diminished expression of CD13 myeloid transcripts by competitive reverse transcription polymerase chain reaction (RT-PCR)

Normal myeloid cells of monocytic and granulocytic origin express the metallopeptidase cluster of differentiation 13 (CD13) on the surface just as leukemic blasts in most acute myeloid leukemias (AML). A minor percentage of AML patients, however, lack the surface expression of CD13 antigen. To study this difference in CD13 surface expression, specific CD13 mRNA from 44 individuals were quantified by competitive reverse transcription polymerase chain reaction (RT-PCR). Absolute values for CD13 transcripts were normalised against glyceraldehyde-3-phosphate dehydrogenase (GAPDH) transcript levels to control for variations in sample preparation and mRNA degradation. By correlating normalised CD13 transcript levels and CD13 surface expression, a subgroup of AML patients was identified, having simultaneous diminished levels of myeloid CD13 transcripts and surface expression of the corresponding antigen. For this subgroup we suggest CD13/aminopeptidase N (APN) gene expression to be restricted primarily by limited amounts of transcripts. For the majority of AML patients determinants in addition to transcript levels must be involved in regulating CD13/APN gene expression.

Messenger ribonucleic acid levels of pregnancy-associated plasma protein-A and the proform of eosinophil major basic protein: expression in human reproductive and nonreproductive tissues

PAPP-A/proMBP, the complex of pregnancy-associated plasma protein-A (PAPP-A) and the proform of eosinophil major basic protein (proMBP), circulates at increasing levels during pregnancy. The major site of synthesis is the placenta, in which PAPP-A mRNA has been localized to the syncytiotrophoblast and the placental X cells, whereas proMBP mRNA has been localized to the placental X cells only. The function of PAPP-A/proMBP and its components has remained speculative for years. Recently, however, it has been shown that PAPP-A specifically cleaves insulin-like growth factor (IGF) binding protein-4 in an IGF-dependent manner. Female reproductive and nonreproductive tissues have previously been reported to contain PAPP-A immunoreactivity, based on studies using preparations of anti(PAPP-A/proMBP), now known to recognize both PAPP-A and proMBP, and other irrelevant antigens. To analyze for the presence of PAPP-A and proMBP mRNA, a sensitive semiquantitative reverse transcription (RT) polymerase chain reaction (PCR) method was developed. Reverse-transcribed poly(A)(+) RNA was used as a template in a competitive PCR. PAPP-A and proMBP mRNA levels were normalized against the level of beta-actin mRNA. Both mRNA species were significantly more abundant in term placenta than in other tissues analyzed. All analyzed tissues, including endometrium, myometrium, colon, and kidney, contained both PAPP-A and proMBP mRNA.

Differential diagnosis based on immunological-phenotyping in suspected malignant bone marrow involvement in childhood

The diagnostic value of immunophenotyping (IP) as a first-line diagnostic method in diseases that infiltrate the childhood bone marrow (BM) or mimic infiltrated BM was examined. Two hundred and fifty unselected BM samples from 250 children suspected to have a malignancy infiltrating their BM were evaluated by means of IP and conventional morophological-cytochemical (MC) studies. We applied the alkaline phosphatase anti-alkaline phosphatase method for IP using a panel of monoclonal antibodies (Mabs) against leukocyte-associated antigens, neuroectodermal antigens, and intermediate filament antigens. Four cases of neuroblastoma, two cases of Ewing sarcoma, and one case of rhabdomyosarcoma were diagnosed by IP but not by MC studies. In nine cases of acute leukemia bone marrow blasts could not be ascribed to a specific lineage on the basis of blast morphology or histochemistry. Eight samples without morphological evidence of malignant infiltration revealed an increased percentage of immature B cell precursors (CD10+, TdT+) suggesting acute lymphoblastic leukemia. None of these children has developed malignant lymphoproliferative disease. Our data suggest that the immunological evaluation of BM in childhood is highly capable of discriminating between different malignant populations but it does not recognize malignancy and therefore supplements but cannot replace conventional methods for diagnosis.

Contribution of immunophenotypic and genotypic analyses to the diagnosis of acute leukemia

Diagnostic accuracy in acute leukemia (AL) can be improved if traditional morphology and cytochemistry are supplemented with immunophenotypic and genotypic analyses. This multiparameter approach is of crucial importance for the management of patients, as it enables the identification of leukemic syndromes with distinct biological features and response to treatment. Immunophenotyping using monoclonal antibodies has been universally accepted as a useful adjunct to morphological criteria. This technique is particularly valuable in diagnosing and subclassifying acute lymphoblastic leukemia and is also essential in certain types of acute myeloid leukemia (AML), such as AML with minimal differentiation or acute megakaryoblastic leukemia. Cytogenetic findings can be quite helpful in establishing the correct diagnosis and can add information of prognostic significance. A number of specific chromosomal abnormalities have been recognized that are very closely, and sometimes uniquely, associated with morphologically and clinically distinct subsets of leukemia. An even more basic understanding of normal and malignant hematopoietic cells has begun to evolve as molecular biology begins to unravel gene misprogramming by Southern and Northern blot analysis, the polymerase chain reaction, and fluorescence in situ hybridization. With the extensive use of these techniques it has become apparent that a proportion of leukemias exhibit the biologically relevant molecular defect in the absence of a karyotypic equivalent. On the other hand, apparently uniform chromosomal abnormalities such as the t(1;19) (q23;p13), t(9;22) (q33;q11), t(8;14) (q24;q32), or t(15;17) (q21;q21) may differ at the molecular level. Data collected from these modern technologies have introduced a greater complexity, which needs to be taken into consideration to improve both the diagnostic precision and the reproducibility of current classifications.

Glial differentiation: a review with implications for new directions in neuro-oncology

Major advances in cell culture techniques, immunology, and molecular biology during the last 10 years have led to significant progress in understanding the process of normal glial differentiation. This article summarizes our current understanding of the cellular and molecular basis of glial differentiation based on data obtained in cell culture and reviews current hypotheses regarding the transcriptional control of the gene switching that controls differentiation. Understanding normal glial differentiation has potentially far-reaching implications for developing new forms of treatment for patients with glial neoplasms. If oncogenesis truly involves a blockage or a short circuiting of the differentiation process in adult glial progenitor cells, or if it results from dedifferentiation of previously mature cells, then a clear understanding of differentiation may provide a key to understanding and potentially curtailing malignancy. Differentiation agents represent a relatively new class of drugs that effect cellular gene transcription at the nuclear level, probably through alterations in chromatin configuration and/or differential gene induction. These exciting new agents may provide a means of preventing the dedifferentiation of low-grade gliomas or inducing malignant glioma cells to differentiate with minimal toxicity. In the future, genetic therapy has the potential of more specifically rectifying the defect in genetic control that led to oncogenesis in any given tumor.

Acute myeloid leukaemia with an unusual phenotype: myeloperoxidase (+), CD13 (-), CD14 (-) and CD33 (-)

We herein describe an unusual case of acute myeloid leukaemia (AML) showing strong cytochemical reactivity for myeloperoxidase (MPO) but surprisingly no reactivity using flow cytometry for any of the lineage-specific cell surface markers, i.e. myelomonocytic antigens CD13, CD14 and CD33; or B-lymphoid antigens CD19, CD20 and immunoglobulins; or T-lymphoid antigens CD2, CD3 and CD5. The strong reactivity for MPO and the complete absence of reactivity for CD13 and CD14 was verified by an independent assay involving alkaline phosphatase-anti-alkaline phosphatase (APAAP). Our case is of interest for at least two reasons: First, a poorly differentiated variant of AML (negative for MPO but positive for one or more of the myeloid-lineage CD antigens) has been designated FAB M0. In terms of the expression of phenotypic markers, our case may be considered as an 'MPO (+), CD antigen (-) AML'. The CD antigens are known to be expressed very early during myeloid differentiation whereas MPO (in its functional form) is viewed as being expressed relatively late in the process. It is therefore intriguing from a biological standpoint why the supposedly early antigens (CD33 and CD13) remain unexpressed; this may represent an example of 'asynchronous differentiation' in leukaemia. Second, from a practical standpoint, the use of immunophenotyping as a first-line diagnosis would fail to detect such cases. This case strengthens the notion that immunophenotyping by flow cytometry does not eliminate the necessity of performing peroxidase cytochemical staining.

Surface expression of the alpha 2-macroglobulin receptor on human malignant blood cells

The surface expression of the alpha 2-macroblobulin receptor (alpha 2MR), detected by a monoclonal antibody, A2MR alpha-2, was determined on mononuclear blood cells from 90 cases of malignant blood disease. Flow cytometric analyses combined with immunoblotting and ligand binding experiments revealed that alpha 2MR was expressed on malignant cells from patients with acute and chronic myelomonocytic leukemias, while no significant expression was found on malignant cells from acute and chronic lymphatic leukemia, lymphomas, plasma cell leukemias or hairy cell leukemia. In acute myeloid leukemia, alpha 2MR was expressed in 50% of the M4-M5 cases, but only in three of thirty of the morphologically undifferentiated or non-monocytic cases (M1-M3 and M6). In chronic myelomonocytic leukemia five of seven cases were alpha 2MR-positive, while only one of seven cases of chronic myeloid leukemia was positive. The monocytic nature of the hematopoietic cells reacting with A2MR alpha 2 was further confirmed by a close correlation with CD14 surface expression.

Monoclonal antibodies in myeloid diseases: prognostic use in acute myeloid leukaemia

Bone marrow cells from 109 patients (median age 60) with newly diagnosed acute myeloid leukaemia (AML) were prospectively immunophenotyped (IP) and the prognostic value of monoclonal antibody (MAB) reactivities was analysed to detect differences in complete remission rates and survival, not only between groups of MAB + and - bone marrow cells, but also in cases with or without prominent MAB reactivity as compared to normal BM reactivity of the respective MABs. This approach was based on the assumption that the qualitative expression of antigens is not an all or none phenomenon, but that different degrees of expression of antigens exist. Patients with significantly elevated CD13 (MY7+) cells in bone marrows (CD13 greater than reference value + one standard deviation) (S.D.) showed decreased probability of entering CR (p less than 0.05) and a significantly shorter survival (p less than 0.05). Superior CR rates (p less than 0.05) without difference in long-term survival were seen in patients with low CD33 (MY9) or low HLA-DR expression, while high CD14 (MY4) expression showed a trend towards an adverse factor (p = 0.12). No other antibody reactivities showed differences in CR rates (CD3, CD20, CDw65 (VIM-2) and NAT-9). The more prominent bone marrow expression of CD33 antigen than CD13 (CD33/CD13 greater than 1) correlated to a better chance of entering CR (p = 0.01) and to improved survival (p = 0.002), while the expression of high numbers of VIM-2+ cells was a favourable prognostic factor regarding length of survival (p = 0.002). The importance of a high CD33/CD13 ratio as a positive prognostic factor was evaluated using stratified analysis according to age or leucocyte counts at presentation. In both cases, CD33/CD13 was associated with longer survival (age: p = 0.05, leucocyte counts: p = 0.03). A Cox multiparameter analysis revealed that the CD33/CD13 ratio was a favourable prognostic factor (p = 0.03) together with age (p = 0.001) and leucocyte counts in peripheral blood (p less than 0.01). We conclude that establishing the immunologic phenotype can be of prognostic value in cases of AML, especially with regard to the relationship between the CD33 and CD13 antigens.

Monoclonal antibody ratios in malignant myeloid diseases: diagnostic and prognostic use in myelodysplastic syndromes

Based on a 6 1/2-year study of bone marrows (BM) from 74 consecutive adult patients with newly diagnosed primary myelodysplastic syndromes (MDS), we have evaluated the role of immunophenotyping (IP) for subclassification purposes with a selected panel of monoclonal antibodies (Mab). Compared to normal BM IP revealed increased numbers of Mab-defined immature myeloid cells (defined by Mab MY7 [CD13] and MY9 [CD33] (P less than 0.05). Furthermore, decreased numbers of mature myeloid cells (defined by Mab NAT-9 II:3F-6F [NAT-9]) (P less than 0.001) were demonstrated in all French-American-British (FAB) subtypes except refractory anaemia with sideroblasts (RA-S). Since expression of CD13 and CD33 antigens on immature myeloid cells is variable, IP based on a single Mab was often found to be non-informative. However, the construction of myeloid antibody ratios (MAR), designed to give higher figures with increasing numbers of immature myeloid cells and/or decreasing numbers of mature myeloid cells in the BM, disclosed increasing mean ratio values with progressing FAB subtypes. More significant however, was that different prognostic subgroups based on the MAR could be identified independently of the FAB classification. We conclude that the use of IP--especially when MAR is included--is useful in prognostic scoring systems in MDS.