Distinct lymphoblastic and myeloblastic populations in TdT positive acute myeloblastic leukemia: evidence by double-fluorescence staining

Terminal deoxynucleotidyl transferase expression in acute myelogenous leukemia and myelodysplasia as determined by flow cytometry

The significance of terminal deoxynucleotidyl transferase (TdT) expression in acute myelogenous leukemia (AML) remains controversial. Therefore, we studied TdT expression by flow cytometry in 120 previously untreated patients with AML or myelodysplastic syndrome (MDS) to determine the distribution of TdT-positive blasts and the intensity of TdT expression and to seek clinically significant associations. TdT expression measured by flow cytometry (flow TdT%) was heterogeneous, ranging from 0.1% to 87% (median, 8.5%), and 74 patients (62%) had at least 5% TdT-positive blasts. TdT positivity was associated with the M0 or M1 subtype and with expression of CD34 and CD7. No significant correlation was found between TdT expression and type of cytogenetic abnormality or rearrangement of immunoglobulin or T-cell receptor genes. Remission lasted longer in patients with a flow TdT% < 5 than in patients with a flow TdT% > 5 (median, 95 weeks vs 55 weeks, p = 0.02); however, complete remission rates did not differ when patients were classified by initial flow TdT%. Survival was slightly better for patients with flow TdT% less than 5%. Among patients with a flow TdT% > 5%, those with a higher TdT intensity survived longer than those with a lower intensity. These data suggest that quantitative TdT measurement may contribute to prognostic estimate in AML patients.

Detection of terminal transferase in acute myeloid leukemia by flow cytometry

The purpose of this study was twofold: (1) to develop an optimized, reliable method for the flow cytometric analysis of the intranuclear DNA polymerase, terminal deoxynucleotidyl transferase (TdT) in acute myeloid leukemia, and (2) to establish the usefulness of a novel, fluorescein-isothiocyanate conjugated monoclonal anti-TdT antibody (HT-6) in double-fluorescence staining for surface antigens in the characterization of leukemic cells. Inclusion of an aldehyde blocking buffer in the staining protocol reduced background fluorescence sufficiently to allow for the detection of the low-level fluorescent TdT+ myeloblasts. When admixed to normal peripheral blood mononuclear cells, 0.4-0.5% of HLA-DR+ or myeloid surface antigen+, TdT+ double-stained myeloblasts could be reliably detected above background levels. Flow cytometric TdT measurements using the HT-6 antibody in 55 patients with TdT+ acute lymphocytic or myelocytic leukemia or blast crisis of chronic myelogenous leukemia were equal or superior to the results obtained with a mixture of monoclonal anti-TdT antibodies (anti-HTDT-Mix) and comparable to those obtained by the conventional slide method employing polyclonal rabbit anti-human TdT antiserum. This flow cytometric TdT determination in combination with surface antigen staining using a novel anti-TdT monoclonal antibody (HT-6) allows for the recognition of minimal leukemic blast cells during clinical remission in acute myeloid leukemia.

Differential expression of terminal transferase (TdT) in acute lymphocytic leukaemia expressing myeloid antigens and TdT positive acute myeloid leukaemia as compared to myeloid antigen negative acute lymphocytic leukaemia

We examined whether the allegedly aberrant expression of the lymphoid lineage associated DNA polymerase, terminal deoxynucleotidyl transferase (TdT), in acute myeloid leukaemia (AML) is associated with alterations of the enzyme at the cellular, biochemical or transcriptional level when compared to lymphoid leukaemia (ALL), either lacking or expressing myeloid antigens. By flowcytometric analysis, the intensity of TdT staining with monoclonal anti-TdT antibody was considerably weaker in TdT+ AML and myeloid+ ALL (M+ ALL) than in myeloid- ALL (M- ALL). TdT enzyme activity in TdT+ AML was on an average 10%, and in M+ ALL 25% of that measured in M- ALL. Anti-TdT antibodies precipitated a major specific protein of identical relative molecular mass (58 kD) from metabolically labelled TdT+ myeloblasts and lymphoblasts. By Northern blot analysis and ribonuclease protection assay, TdT transcript levels were significantly lower in TdT+ myeloblasts and M+ lymphoblasts than in M- ALL (P < 0.0001). The level of TdT transcription in AML was independent of the simultaneous expression of lymphoid-specific antigens, such as CD2 and CD19. Our data demonstrate that TdT expression is downregulated in association with myeloid features, not only in AML but also in ALL. This observation may provide the molecular basis for the differential therapeutic responsiveness, particularly to glucocorticoids, in these various leukaemia subtypes.

Surface marker analysis and karyotype distinguish acute biphenotypic leukemia from acute myelogenous leukemia expressing terminal deoxynucleotidyl transferase

Surface phenotyping by flow cytometry and cytochemical study were used to identify 15 adult patients with acute leukemia displaying ambiguous phenotypes. Differences were found in the blast cell karyotype and immunoglobulin gene rearrangements of terminal deoxynucleotidyl transferase (TdT)-positive acute myelogenous leukemia (AML) and biphenotypic leukemia expressing B lymphoid and myeloid markers. The karyotypic abnormalities, t(9;22) and t(4;11), were noticed in acute biphenotypic leukemia, and were consistently associated with rearrangement at the immunoglobulin locus. Furthermore, coexpression of CD19/CD20 and either myeloperoxidase or myeloid surface markers were predictive of finding the t(9;22) or t(4;11) karyotype. Patients with TdT-positive AML, on the other hand, were less likely to show rearrangement at the immunoglobulin locus, and did not have the t(9;22) or t(4;11). Instead, a variety of nonrandom karyotypic abnormalities were seen, including trisomy 13. Unlike common AML, the majority of TdT-positive cases demonstrated an abnormal karyotype with duplications and/or deletions present in all cases. In no instance was trisomy 8, t(8;21), t(15;17), or any other isolated translocation identified. The authors therefore suggest that immunophenotyping, when combined with cytochemical analysis of TdT and myeloperoxidase or Sudan black B, may aid in the characterization of subgroups of atypical acute leukemia, such that alternate approaches to therapy can be evaluated.

Unexpected immunoglobulin light chain gene rearrangements in myeloid antigen positive acute lymphoid leukemia

Blast cells from 10 immunologically diagnosed adult acute lymphoid leukemias expressing myeloid antigens (M+ALL) were studied for immunoglobulin heavy (IgH) and light chain as well as T-cell receptor (TCR)-beta chain gene rearrangements. All but one leukemic isolate met the FAB-criteria for ALL. DNA from 2 patients with pre-pre-B-ALL (CD10-) and 1 patient with common ALL contained rearranged Ig light chain (kappa in two, lambda in one case) in addition to rearranged IgH genes. The TCR-beta chain gene was germline in all pre-pre-B leukemias and rearranged in common ALLs (bigenotypic features). One patient with mature B-ALL showed IgH and light chain gene rearrangements. DNA from 2 pre-T-ALLs contained rearranged TCR-beta chain genes plus rearranged IgH genes in one case. Ig light chain gene rearrangements in immature M+ALL were not associated with gross chromosomal abnormalities except for one Philadelphia chromosome positive case. The occurrence of Ig light chain gene rearrangements in M+ALL with immature lymphoid immunophenotype might represent an hitherto unrecognized aberrant differentiation potential of transformed multipotential stem cells with commitment towards the lymphoid lineage.

Transformation of bilineal hybrid acute leukemia to acute lymphoid leukemia: a case report with serial analyses of cytogenetics and gene rearrangement

A 17-year-old male with bilineal hybrid acute leukemia is described. Two-color flow cytometric analysis of blast surface phenotype revealed that there were two groups of blasts which showed either CD 10+ CD 19+ CD 13- CD 33- or CD 10- CD 19- CD 13+ CD 33+, but not both. He developed a complete remission by treatment with vincristine, prednisolone, adriamycin, and L-asparaginase. After 8 months, however, leukemia relapsed and lymphoid blasts were dominant. Cytogenetic analysis at presentation showed 46,XY,t(3;9)(p21;p22), and at relapse it showed 46,XY,t(1;3;9)(1pter----1q32::3p25----3pter;3 qter----3p21::9p22----9pter; 9qter----9p22::3p21----3p25::1q32----1q ter),t(2;19)(p21;q13). Analysis of the heavy chain joining region at diagnosis showed three hybridizing bands, all rearranged, but at relapse only one rearranged band. Analysis of the constant region for the beta T-cell receptor gene (TCR beta) both at diagnosis and at relapse showed one rearranged and one germline band, suggesting that rearrangement of one allele of TCR beta of not only lymphoid but also myeloid blasts occurred. It is considered that the target cell of lymphoid leukemia cells and that of myeloid leukemia cells at diagnosis were the same, which differentiated to two lineages, and the clone which evolved from lymphoid lineage proliferated at relapse.

Clonal analysis of childhood acute lymphoblastic leukemia with "cytogenetically independent" cell populations

Acute lymphoblastic leukemia (ALL) is generally regarded as a clonal disease in which a single abnormal progenitor cell gives rise to neoplastic progeny. Five of 463 cases of childhood ALL with adequately banded leukemic cells were found to have two cytogenetically independent cell populations. In addition, two of the four cases tested had more than two rearranged immunoglobulin genes and (or) T cell receptor genes. To investigate the clonality of these unusual leukemias, we examined the neoplastic cells for X-linked markers extrinsic to the disease. Leukemic cells from each of the three patients heterozygous for an X-linked, restriction fragment length polymorphism showed a single active parental allele, suggesting that both apparently independent cell populations developed from a common progenitor. These cases provide evidence that leukemogenesis involves a multistep process of mutation and suggest that karyotypic abnormalities may be a late event of malignant transformation.

Hybrid acute leukemia in an HIV-antibody-positive patient

Although the great majority of acute leukemias have been designated as being of lymphocytic or myelocytic origin, recent reports have described elements of both in some patients. We describe here the first case of hybrid acute leukemia in an HIV-antibody-positive patient as well as the first hybrid involving B-cell (Burkitt) acute lymphocytic leukemia and acute myelomonocytic leukemia proven by cytochemical, immunologic, and cytogenetic methods. This case illustrates the increasingly complex difficulties in the diagnosis and treatment of AIDS-related malignancies.

Terminal deoxynucleotidyl transferase and HLA-DR expression appear unrelated to prognosis of acute myeloid leukaemia

Mononuclear cells from peripheral blood or bone marrow from 314 patients with acute myeloid leukaemia were examined for the presence of nuclear terminal deoxynucleotidyl transferase (304 patients), surface membrane expression of HLA-DR (314 patients) and the common acute lymphoblastic leukaemia antigen (281 patients). All patients were treated with identical remission induction chemotherapy, and morphological diagnosis was carried out in a central laboratory. The overall complete remission rate was 70%. There were no significant correlations between the immunological markers and complete remission rate, duration of remission, or survival.

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

In a prospective analysis of the diagnostic value of immunophenotyping in acute leukemias (ALs), all patients admitted to a pediatric and a haematological department suspected of AL were examined consecutively with a selected panel of monoclonal antibodies (Mabs) against leucocyte differentiation antigens during an 8-month period. A total of 189 samples obtained from blood, bone marrow, spinal fluid and lymph nodes in 120 cases were all analysed blindly. The results were correlated with a routine morphological/cytochemical evaluation. Differing results were obtained in seven out of 38 cases in which the immunologically defined diagnosis was acute myeloid leukemia (AML), and in one out of 21 cases with the primary diagnosis acute lymphoid leukemia (ALL). Immunological phenotyping disclosed two cases of hybrid leukemia, one case of biphenotypic and one case of bilineal leukemia. No evidence of malignancy was found in 36 cases, 30 cases of blood and bone marrow and six cases of spinal fluids, in every case in accordance with the pathological examination. These results demonstrate that a first-line immunological evaluation of bone marrow, blood and spinal fluid from patients suspected of AL is highly capable of discriminating between different malignant and nonmalignant haematological diseases and also between various types of leukemias. The immunological methods do, however, require a sufficient amount of material which was a limiting factor in 14 out of 120 examinations, mainly from patients treated with several cycles of cytostatics. It is concluded that immunophenotyping can be used as a first-line diagnostic tool in malignant haematological diseases.

Cell cycle-related expression of surface antigens on myelomonocytic leukemia cells

We investigated the relationship between the expression of surface antigens and the cell cycle phase in leukemic cells from cell lines and one patient using two-color flow cytometry, in order to determine the reason for the uneven expression of some markers which frequently leads to equivocal results as to leukemic phenotyping. As a result, it was demonstrated that monocyte-related differentiation markers, including I2, My4, Mo1 and Mo2, on monocytoid leukemic cells are preferentially expressed at the G0/G1 phase. Consequently, it is expected that the positivities for such markers vary with the proliferation status of the leukemic cells.

In vitro differentiation of a null-acute leukemia: T-lymphoid surface antigen expression associated with rearrangement in T-cell receptor beta chain variable genes

We describe a human acute unclassified leukemia with a unique t(4;17) translocation that coexpresses T-lymphoid and myeloid surface antigens after in vitro culture in the presence of the tumor promoter, TPA. Under these conditions, the joining regions of the immunoglobulin heavy chain and T-cell receptor gamma and beta chain complexes remained in germ line configuration. A T-cell receptor beta chain variable gene probe, however, revealed the presence of rearrangements in the V beta M3-2 gene region after bilineage differentiation. These results may be pertinent to the interrelationship of T-cell receptor gene rearrangements and the control of T-cell antigen surface expression.

Undifferentiated leukemia of infancy with t(11:17) chromosomal rearrangement. Coexpressing myeloid and B cell restricted antigens

It has been suggested that the malignant transformation, in some of the acute leukemias, may involve totipotent stem cells resulting in a biphenotypic leukemia expressing both myeloid, and lymphoid characteristics. We describe here a hybrid cell acute leukemia, in a 16-day-old infant, in whom leukemic cells coexpressed myeloid and lymphoid B cell antigens. Blast cells in the bone marrow showed L2 morphology according to the French American British (FAB) classification, with positive periodic-acid Schiff, and nonspecific esterase staining. Sudan black, and specific esterase were negative. Terminal deoxynucleotidyl transferase, was strongly positive in 5% of blasts, and faintly reactive with the rest. Karyotypic analysis demonstrated a translocation of t(11:17);(q23;p13). Immunoglobulin gene analysis revealed rearrangement of the heavy chain genes. The blasts' phenotype was HLA/DR+ B4+ My7+ My9+ common acute lymphoblastic leukemia antigen (CALLA) B1- T11-. Dual immunofluorescence staining using anti My7, and My9 fluorescein isothiocyanate, and anti B4 pycoerythrin conjugated monoclonal antibodies, and flow cytofluorometry, revealed a labeling pattern of 25% B4+; 10% to 15% My7+; 17% My9+; and 50% of cells coexpressing B4 My7, and My9 antigens. These results provide evidence for a hybrid leukemia with lymphomyeloblasts being part of a single clone, which may indicate the origin of this leukemic clone from a pluripotent (lymphoid/myeloid) stem cell.

Biphenotypic leukemia with unusual chromosomal translocation in a patient treated for melanoma

A patient in complete remission from malignant melanoma but with refractory anemia after nitrosourea treatment developed acute biphenotypic leukemia. This disease, progression was accompanied by expansion of a cytogenetically abnormal clone. At first cytogenetic analysis, 1 year post discontinuation of chemotherapy, only 25% of the metaphases examined were hypodiploid with monosomy 7. Six months later, all of the metaphases seen were 45,XY,-7. Six months before overt acute leukemia was diagnosed, an additional chromosome abnormality emerged, t(2;3)(q31;q27). Although the translocation was present in all metaphases examined, the patient progressed into an acute leukemia with two components: one TdT-positive, Ia-positive, and the other TdT-negative, Ia-positive, monocytoid antigen-positive. This mixed leukemia was identified by double fluorescence staining for intranuclear TdT and surface labeling with a monocyte-specific monoclonal antibody.

Biphenotypic lymphoblastic lymphoma. An unusual tumor with lymphocytic and granulocytic differentiation

An unusual example of a lymphoblastic lymphoma with evidence of both T-lymphocytic (Leu-1, Leu-2, Leu-3, OKT-6, terminal transferase-positive) and immature granulocytic (Mo1, chloroacetate esterase, lysozyme, alpha-1-antitrypsin-positive) cell proliferations was studied. The tumor arose in the oropharynx of a 39-year-old man without evidence of blood or bone marrow involvement. This tumor has been termed a "biphenotypic lymphoblastic lymphoma," and the origin of which appears to be from uncommitted progenitor cells capable of both lymphoid and myeloid differentiation. Biphenotypic lymphoblastic lymphomas, like biphenotypic leukemias, may occur more commonly than is appreciated, and may account for reported cases of acute myeloblastic leukemia after lymphoblastic lymphoma.

Reactivity pattern of 'myeloid monoclonal antibodies' with emphasis on MCS-2

The reactivity pattern of the murine monoclonal antibody (MoAb) MCS-2 was tested on a panel of 724 cases of leukemia-lymphoma. MCS-2 was positive in 178/185 (96%) cases of AML (FAB M1-3), 10/10 cases of AMMol/AMoL (FAB M4/5), 42/45 (93%) cases of CML, 1/1 case of CMoL, 37/38 (97%) cases of CML-myeloid blast crisis, 0/9 cases of CML-lymphoid blast crisis. No positive staining was seen in 238 cases of T-CLL, mycosis fungoides, Sèzary-syndrome, B-CLL, hairy cell leukemia, multiple myeloma and T- and B-lymphoma nor in 32 cases of B-ALL, Burkitt-lymphoma, Null-ALL and immature T-lymphoma. A positive expression was found in 8/110 cases of cALL, 1/6 cases of pre B-ALL and 1/35 cases of T-ALL. Fifteen other MoAbs (MCS-1, OKM1, My-1, Leu-M1, Leu-M3, CA-2-38, MY4, MY7, MY8, MY9, VIM-D2, VIM-D5, Mol, Mo2, 63D3) which are associated with the myelomonocytic cell lineages were tested by indirect immunofluorescence on 60 or more patients (62-149 cases). A wide variability in the frequency of positivity was seen for the panel of cases studied and for the blast cell populations per individual samples: 21-96% of the AML cases (FAB M1-3) and 31-100% of the AMMoL/AMoL cases (FAB M4/5) were positive for the various MoAbs. None of the analysed MoAbs stained only myelocytic or only monocytic leukemias, but a certain degree of preference for the monocytic variants was noted for Leu-M3, CA-2-38, MY4, VIM-D2, Mo2 and 63D3. The detection of MCS-2 on immature ALL blast cells might indicate a coexpression of lymphoid and myeloid markers on very immature cells, or an abnormal gene expression by malignant cells, or the identification of a so far undetected subclass of acute leukemias.

An analysis of the presence of Fc receptors on bone marrow lymphoblasts in acute lymphoblastic leukemia. A Pediatric Oncology Group study

The presence or absence of the Fc receptor (FcR) on bone marrow lymphoblasts was evaluated in 279 cases of acute lymphoblastic leukemia (ALL) by member institutions of the Pediatric Oncology Group (POG). The case material was classified as follows: 19 cases of positive (greater than or equal to 20% +), 24 additional cases as intermediate (greater than or equal to 10% but less than 20%), and the remaining 236 cases as negative (less than 10%). Intermediate and positive cases were relatively equally distributed between null cell leukemia and pre-B-cell leukemia, and there were one intermediate and two positive T-cell cases. One of two cases of B-cell leukemia was also positive. There were no distinguishing clinical or laboratory characteristics which distinguished the FcR+ cases, nor was the FcR of prognostic significance within ALL as a group or within immunologically defined phenotypes.

Biochemical enzyme analysis in acute leukaemia

This report summarises the current knowledge regarding the clinical utility of biochemical enzyme markers for both diagnostic and therapeutic purposes in acute leukaemia. The enzymes studied most extensively in this field are terminal deoxynucleotidyl transferase, adenosine deaminase, 5'-nucleotidase, purine nucleoside phosphorylase, and acid phosphatase, esterase, hexosaminidase isoenzymes. For each enzyme, the quantitative and qualitative characteristics in various immunologically defined subclasses of acute leukaemia are described. The quantitative evaluation of enzyme activities represents an adjunctive classification technique which should be incorporated into the multivariate analysis, the "multiple marker analysis." By qualitative characterisation pronounced heterogeneity of leukaemia subsets is uncovered. The application of 2'-deoxycoformycin, a specific inhibitor of adenosine deaminase, and the potential usefulness of two other enzymes as targets for treatment with selective agents is discussed. The concept that gene products expressed at certain developmental stages of normal cells can similarly be detected in leukaemic cells (which therefore seem to be "frozen" or "arrested" at this particular maturation/differentiation stage) is supported by the results obtained in enzyme studies. Besides their practical clinical importance for classification and treatment of acute leukaemias, biochemical enzyme markers constitute a valuable research tool to disclose biological properties of leukaemic cells.

Subdivision of the acute non-lymphoblastic leukaemias by measurement of the relative abundance of a specific RNA sequence

A recombinant plasmid library representing the more abundant polyadenylated RNA of a relapsed acute myelomonocytic leukaemic (FAB class M4) has been constructed. One recombinant, designated pAM6, contains a DNA sequence complementary to an RNA of about 1100 nucleotides in length. The relative concentrations of pAM6 RNA in the RNAs from cloned human haematopoietic cell lines and from fractionated leukaemic leukocytes and normal bone marrow cells, measured by an RNA dot hybridization method, indicated that pAM6 RNA occurs in myeloid cells, probably those of the monocyte lineage at the earlier stages in differentiation. Similar assays showed that pAM6 RNA could not be detected in the peripheral blood leukocytes of normal individuals, or of ALL and CLL patients, but that the relative abundance of pAM6 RNA varied widely in leukocytes from CGL chronic phase, CGL acute phase, and ANLL. No correlation between pAM6 RNA occurrence and FAB classification of ANLL could be made; thus it would appear that the relative abundance of pAM6 RNA in ANLL leukocytes can be used to subdivide the ANLLs in a novel manner. It is suggested that this criterion, in conjunction with existing diagnostic markers, may provide a subclassification of the ANLLs that could be of some prognostic and therapeutic value.

Plasmacytoid blast crisis in B-cell chronic lymphocytic leukemia: effect of estradiol on growth and differentiation in vitro

Evolution of a case of chronic lymphocytic leukemia (CLL) into blast crisis was found to be characterized by three unusual features (1) the phenotype of the emerging blast cells was that of pre-plasmacytoid cells as shown by plasma cell morphology and an immunological phenotype corresponding partially with CLL- or intermediate B-cells, partially with plasma cells (terminal transferase-, common acute lymphocytic leukemia antigen-, Ia+, surface immunoglobulin heavy chains-, surface kappa light chains+, intracytoplasmic immunoglobulin A+ and G+, BA-1+, polyclonal gammaglobulin production); (2) cytogenetic analysis of spontaneous metaphases revealed that in addition to the typical CLL abnormality, trisomy 12, in all of the cells, an additional translocation between chromosomes 14 and 17 was present in 40% with a presumptive breakpoint on chromosome 14 (q12-3) never described before (commonly q32) and (3) the progression of the disease was associated with a striking increase in the expression by the transformed cells of specific binding sites for estradiol (E2) due to an actual increase in total cellular receptor proteins and not to a change in receptor affinity for E2. The functional status of the steroid receptors was confirmed by nuclear transfer of the cytoplasmic hormone-receptor complex upon temperature activation. Since the rise in E2-receptor display paralleled a large increase in the proliferative activity of the cells as well as a change in their maturation status the question was raised as to whether the E2-receptor should be considered as a physiological marker of growth rate or of cellular differentiation. Exposure of the patient's blast cells to E2 in vitro resulted in cessation of cell growth following at least one mitosis after addition of the inducer as seen from the replacement of the large blasts by small CLL-like cells without definite signs of alteration of the differentiation status. This suggests the association of E2-receptor expression with control of growth rather than cell maturation.

Phenotype of the terminal transferase-positive cells in human foetal liver and bone-marrow: analysis with monoclonal antibodies

Liver and bone-marrow of 20 human foetuses between 15th and 20th week of gestational age were examined. Mononuclear cells were labelled with murine monoclonal antibodies to reveal surface antigens and with a rabbit antiserum to TdT for the detection of the nuclear enzyme, using a double colour indirect immunofluorescence technique. The results have revealed that TdT+ cells express the phenotype of B cell precursors HLA-DR+, CALLA+, FMC8+, LEU-1-, LEU-5-, LEU-9-. It suggests that foetal liver and bone-marrow have an active function in B-lymphopoiesis in humans. The involvement of TdT in the process of B-cell immunological acquisition is uncertain because only humans and Xenopus embryos, among the species examined, express TdT outside the thymus during ontogenesis.