Phenotypic conversion of T lymphoblastic lymphoma to acute biphenotypic leukemia composed of lymphoblasts and myeloblasts. Molecular genetic evidence of the same clonal origin

Constitutively active beta-catenin confers multilineage differentiation potential on lymphoid and myeloid progenitors

Beta-catenin-mediated Wnt signaling may contribute to the self-renewal of hematopoietic stem cells and proliferation in some malignancies. We now show that expression of constitutively active beta-catenin in normal lymphoid or myeloid progenitors generated uncommitted cells with multilineage differentiation potential. Inappropriate gene expression occurred in cells destined to produce either cell type and caused corresponding changes in their characteristics. For example, forced activation of beta-catenin quickly increased C/EBPalpha while reducing EBF and Pax-5 in lymphoid progenitors that then generated myeloid cells. Inversely, EBF dramatically increased in transduced myeloid progenitors and lymphocytes were produced. The results indicate that ectopic activation of beta-catenin destabilizes lineage fate decisions and confers some, but not all, stem cell properties on committed progenitors.

Successful reduced-intensity stem cell transplantation from an HLA haploidentical 3-loci-mismatched donor on the basis of fetomaternal microchimerism in a patient with advanced acute myeloid leukemia

A 31-year-old woman with advanced acute myeloid leukemia underwent non-T-cell-depleted (TCD) peripheral blood stem cell transplantation (PBSCT) with a reduced-intensity conditioning regimen. The donor was an HLA haploidentical 3-loci-mismatched complementary sibling who had not inherited maternal HLA antigens. Long-term fetomaternal microchimerism was detected by nested polymerase chain reaction with specific primer typing. Graft-versus-host disease (GVHD) prophylaxis consisted of tacrolimus with minidose methotrexate. Durable engraftment was achieved without severe acute GVHD, and complete remission was obtained. Thus non-TCD HLA haploidentical reduced-intensity PBSCT based on fetomaternal immunological tolerance appears to be feasible. Our results have important implications in the selection of alternative donors and conditioning regimens for allogeneic hematopoietic stem cell transplantation.

A novel c-kit positive biphenotypic acute leukemia cell line, TMBL-1, carrying a p53 point mutation

We established and characterized a c-kit positive cell line from the bone marrow of a patient with biphenotypic acute leukemia (BAL). The cell line, designated TMBL-1, carried a His-175 mutant p53. The immunophenotype of the primary leukemia cells at diagnosis was cytoplasmic CD3+, CD7+, CD13+, CD33-, interleukin-7 (IL-7) receptor+ and c-kit -. However, leukemia cells in relapse and TMBL-1 cells were CD33+ and c-kit +. Immunophenotypically, TMBL-1 is a BAL cell line that coexpresses T-lymphoid and myeloid markers which fulfill the criteria of the European Group for the Immunological Characterization of Leukemia. Stem cell factor (SCF), a key regulator of hematopoiesis signaling through c-kit, enhanced the proliferation of TMBL-1 cells. Direct sequencing revealed the conversion at codon 175 of the p53 gene in the TMBL-1 cells. Primary leukemia cells in relapse also carried the same point mutation but not at diagnosis. Moreover, TMBL-1 cells are sensitive to paclitaxel, which could induce p53-independent apoptosis. The biphenotypic features and p53 mutation may be associated with progression to a more malignant type. This cell line may provide new information on the role of SCF in the overlapping area between early T-lymphoid/myeloid cells, and help in the design of new therapies targeted towards p53 mutations.

What can we learn from leukemia as for the process of lineage commitment in hematopoiesis?

Most contemporary models of hematopoiesis assume lineage fidelity of early progenitor cells. Along with this concept normal hematopoietic cells and the majority of leukemias express exclusively myeloid or lymphoid specific antigens. On the other hand, growing evidence exists challenging the lineage fidelity model. Chronic myeloid leukemia (CML) in the blast crisis may switch to acute lymphoblastic leukemia (ALL) and as a result of the chemotherapy ALL may converse to acute myeloid leukemia (AML). Furthermore, a substantial portion of leukemia cases, named acute mixed-lineage leukemia (AMLL), show simultaneous expression of both myeloid and lymphoid antigens. Immunoglobulin (Ig) and T-cell receptor (TCR) gene rearrangements, correlating with myeloid-lymphoid immunophenotype in AMLL, support the hypothesis of lineage infidelity of early progenitor cells, rather than the aberrant antigen expression. Based on a detailed characterization of AMLL we present a modified model of a "common myeloid/lymphoid progenitor cell". This hypothetical very early hematopoietic progenitor cell shows a transient expression of myeloid and B- or T-lymphoid antigen and may also have rearranged its Ig and/or TCR genes. Subsequently, myeloid or lymphoid markers are downregulated and the hematopoietic cell enters either myeloid, T-lymphoid or B-lymphoid differentiation pathway.

Lymphoblastic lymphoma

Recent advances in the unique clinicopathologic entity of lymphoblastic lymphoma (and its variants) are discussed in this article, which details the natural history, molecular biology, prognosis, and outcome with various chemotherapy regimens. Improved outcome with the newer intensive chemotherapy regimens and the role of modalities such as autologous intensification, allogeneic bone marrow transplant, and radiotherapy are discussed.

T-stem cell leukemia/lymphoma with both myeloid lineage conversion and T-specific delta recombination

We evaluated retrospectively the clinical and biological characteristics of six patients with CD7+ early T-acute lymphoblastic leukemia and lymphoma (T-ALL/LBL) originating from prothymocyte stage I (pro-T I) or II cells. Patients exhibited mediastinal mass (five of six) and lymphoadenopathy (five of six) but without leukocytosis and circulating blast cells (six of six). All patients achieved a complete remission. All but one had a relapse with a transformation to the mixed type (triphenotype--three cases, biphenotype-two cases) including myeloid features in three patients. The altered phenotypes were myeloperoxidase (MPO)+ (three of five), CD13+ (four of five), CD33+ (three of five) and CD19+ (three of five). The difference for MPO-positivity were observed between the bone marrow (BM)- and lymph node (LN)-blast cells (three of three). On cytogenetic analysis, there is no common abnormality in these patients. Immunomolecular analysis revealed T-cell lineage specific delta gene rearrangements [D delta 2-J delta 1 (five of six) and V delta 1-J delta 1 (one of six)] in all cases. Furthermore, D delta 2-J delta 1 occurred even in the cases with the pro-T I phenotype. Rearrangements of TCR beta, gamma or immunoglobulin heavy chain genes occurred in three patients. The same rearranged band(s) appeared at both diagnosis and relapse, indicating the same originality of the pro-T leukemic cell clone (three of three). We suggest that this type of CD7+ early T-ALL/LBL was transformed from a pro-T I or II cell, such as T-stem cell leukemia/lymphoma, which is a subtype of CD7+ stem cell leukemia as defined by Kurtzberg et al. This study reveals that pro-T I and II cells might be capable of myeloid, T- and B-lymphoid differentiation, and T-cell lineage specific TCR delta recombination occurs.

Myeloperoxidase mRNA analysis in acute lymphoblastic leukemia

Expression of the myeloperoxidase (MPO) gene at the mRNA level is a better lineage marker than enzymatic activity in early myeloid precursors and their leukemic counterparts. Its diagnostic use depends on the specificity of expression for myeloblasts and its absence in blasts of lymphoid lineage. The present study investigates MPO mRNA expression in adult acute lymphoblastic leukemia (ALL), using reverse transcription-polymerase chain reaction. Of a total of 13 cases, six were found to have blasts positive for MPO mRNA; in all of these cases, the blasts were cytochemically negative for MPO. This unexpected finding of MPO mRNA positivity in six of 13 cases was further investigated at the molecular level. Bcr gene rearrangement analysis was positive in all six cases for the bcr breakpoint diagnostic of chronic myelogenous leukemia (CML). Only three of these six cases were cytogenetically positive for a Philadelphia (Ph) chromosome. Based on molecular analysis, these cases are considered as CML presenting in blast crisis of lymphoid lineage, as opposed to de novo ALL. The remaining seven cases were Ph negative at the cytogenetic and molecular levels; the leukemic blasts were MPO mRNA negative, confirming the lack of MPO gene expression in de novo ALL.

Lineage determination of CD7+ CD5- CD2- and CD7+ CD5+ CD2- lymphoblasts: studies on phenotype, genotype, and gene expression of myeloperoxidase, CD3 epsilon, and CD3 delta

The gene expression of myeloperoxidase (MPO), CD3 epsilon, and CD3 delta molecules, the gene rearrangement of T-cell receptor (TCR) delta, gamma, and beta and immunoglobulin heavy (IgH) chain, and the expression of cell-surface antigens were investigated in seven cases of CD7+ CD5- CD2- and four cases of CD7+ CD5+ CD2- acute lymphoblastic leukemia or lymphoblastic lymphoma (ALL/LBL) blasts, which were negative for cytochemical myeloperoxidase (cyMPO). More mature T-lineage blasts were also investigated in a comparative manner. In conclusion, the CD7+ CD5- CD2- blasts included four categories: undifferentiated blasts without lineage commitment, T-lineage blasts, T-/myeloid lineage blasts, and cyMPO-negative myeloblasts. The CD7+ CD5+ CD2- blasts included two categories; T-lineage and T-/myeloid lineage blasts. The 11 cases were of the germ-line gene (G) for TCR beta and IgH. Four cases were G for TCR delta and TCR gamma. The others were of the monoclonally rearranged gene (R) for TCR delta and G for TCR gamma or R for both TCR delta and TCR gamma. The expression or in vitro induction of CD13 and/or CD33 antigens correlated with the immaturity of these neoplastic T cells, since it was observed in all 11 CD7+ CD5- CD2- and CD7+ CD5+ CD2-, and some CD7+ CD5+ CD2+ (CD3- CD4- CD8-) cases, but not in CD3 +/- CD4+ CD8+ or CD3+ CD4+ CD8- cases. CD3 epsilon mRNA, but not CD3 delta mRNA, was detected in two CD7+ CD5- CD2- cases, while mRNA of neither of the two CD3 molecules was detected in the other tested CD7+ CD5- CD2- cases. In contrast, mRNA of both CD3 epsilon and CD3 delta were detected in all CD7+ CD5+ CD2- cases, indicating that CD7+ CD5- CD2- blasts at least belong to T-lineage. The blasts of two CD7+ CD5- CD2- cases with entire germ-line genes and without mRNA of the three molecules (MPO, CD3 epsilon, and CD3 delta) were regarded as being at an undifferentiated stage prior to their commitment to either T- or myeloid-lineage. The co-expression of the genes of MPO and CD3 epsilon in a CD7+ CD5- CD2- case MPO, CD3 epsilon, and CD3 delta in a CD7+ CD5+ CD2- case suggested the presence of some overlapping phase for T- and myeloid-lineage commitment during immature stages of differentiation. This helps understand the conversion of some T-ALL/LBL cases to acute myeloblastic leukemia (AML).(ABSTRACT TRUNCATED AT 400 WORDS)

Acute myelogenous leukemia associated with a mediastinal tumor

We describe a 45-year-old female who developed acute myelogenous leukemia (AML) associated with a mediastinal mass. The patient achieved a complete remission accompanied by resolution of the mediastinal mass following intensive chemotherapy alone. A review of the literature disclosed ten AML patients with a mediastinal tumor; all five patients who had mediastinal granulocytic sarcoma treated by local irradiation prior to developing AML, eventually relapsed as frank leukemia and died soon afterwards. On the other hand, three of the other five patients who simultaneously developed both a mediastinal tumor and overt AML achieved complete remission with combination chemotherapy. In conclusion, intensive chemotherapy should be considered for a patient with granulocytic sarcoma of the mediastinum, irrespective of the concomitant leukemia.

Clinical significance of CD7-positive stem cell leukemia. A distinct subtype of mixed lineage leukemia

Ten leukemia cases with mixed phenotype were investigated in terms of clinical characteristics and cellular origin. Three patients were infants and six patients were older children. Six of them had a high leukocyte count and a mediastinal mass was found in three cases. All but one showed hepatosplenomegaly and/or lymphoadenopathy. In spite of intensive chemotherapy, most of them responded poorly. Cytochemical analysis of their leukemic cells revealed a low percentage of positivity for myeloperoxidase reactivity (less than 25%) in two cases and electron microscopic platelet peroxidase reactivity was found in one of three analyzed cases. Phenotypically, these cells all expressed CD7, and other T-lineage-associated, B-lineage-associated, and/or myeloid-associated antigens were also detected to some extent. In addition, three cases expressed CD41 and one case expressed CD56. The T-cell receptor (TCR) genes and immunoglobulin gene were in the germline configuration in seven cases. In three rearranged cases, two showed only the TCR-delta gene rearrangement, and one had both TCR-gamma and delta gene rearrangements. Cell culture studies with 12-0-tetradecanoyl-phorbol-13-acetate (TPA) revealed differentiation to the T-lineage in two cases and to a myeloid lineage in one case. Megakaryocytic differentiation was detected in two cases in culture without TPA. These results suggest that the cells from these cases arose from stem cells capable of both lymphoid and nonlymphoid differentiation. Although the cells were heterogeneous with regard to their potency of differentiation, they have similar clinical characteristics. Because of poor prognosis, it is important to identify this type of leukemia, and allogenic or autologous bone marrow transplantation should be considered.

A classification of acute leukaemia for the 1990s

The need for reproducibility in the classification of acute leukaemia has made it necessary to incorporate information derived from new techniques which have become essential for the study of these disorders. In addition to classic morphology and cytochemistry (FAB proposals), it is necessary to add immunology and cytogenetics (MIC proposals), as well as to investigate further the biological and diagnostic significance of molecular events. As a result of these investigations a new group of leukaemias merit recognition as distinct entities. These include three types of ALL with specific chromosome abnormalities, namely, i) t (9;22), ii) t (4;11) and iii) t (1;19) and four subtypes of AML, i) with minimal differentiation or AML-M0, ii) with basophilic precursors or M2Baso, iii) AML (M4/M5) with t (8;16) and iv) AML with trilineage myelodysplasia. Biphenotypic acute leukaemia constitutes also a distinct entity with features of ALL and AML and represents a malignancy probably affecting multipotent stem cells. We propose an objective evaluation system for biphenotypic leukaemias based on a score in which the various lineage markers are graded according to their known specificity.

Adult T-cell leukemia initially manifesting as facial diplegia

We report an unusual case of adult T-cell leukemia (ATL) initially manifesting as facial palsy due to ATL meningitis, which was caused by lymphoid cells in the cerebrospinal fluid (CSF) with a different phenotype from those in the blood. A DNA southern blot analysis of the blood cells confirmed the diagnosis of ATL. The aberrant cells in the CSF contained nuclei with simple indentations and responded well to the initial chemotherapy, while leukemic cells in the blood showed lobulated or convoluted nuclei and were resistant to treatment. Flow cytometry performed before treatment demonstrated that the majority of the cells in the CSF were CD3+CD4+CD8-CD25+, consistent with ATL, whereas they expressed the CD45R antigen, which the blood ATL cells did not. These differences in the subphenotype, cell morphology, and responsiveness to treatment among the ATL cells in blood and CSF suggest that a single clone or subclone with heterogeneous nature was not generated, before the final development of ATL.

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.

Mature T-lineage leukemia with growth factor-induced multilineage differentiation

We report an acute T-lymphoblastic leukemia with a predominantly mature CD3+ CD7+ WT31+ phenotype that was induced to differentiate into different cell lineages by various recombinant human growth factors. In the presence of IL-3 or GM-CSF, the leukemic cells gave rise to myeloid and monocytic cells including terminally differentiated, partially functional, segmented neutrophilic granulocytes as assessed by morphologic, cytochemical, immunophenotypic, and functional criteria. In the presence of IL-2, leukemic granulated lymphoid cells exhibiting MHC-unrestricted cytotoxicity and expressing a CD2+ CD3+ CD5+ CD7+ CD8+ CD33+ WT31+ Leu19+ phenotype arose. Leukemic cell cultures initiated with IL-3 yielded growth factor-independent cells with a mixed lineage phenotype and morphologic and cytochemical evidence of immature blasts. These were T lymphocyte and myeloid surface antigen (CD2,CD3,CD5,CD7,CD13,CD33,WT31) positive. Identical rearrangements of the constant region of the TCR-delta gene and of the joining regions of the TCR-beta, -gamma, and -delta genes were observed in the fresh and all cultured leukemic cells, indicating that they were derived from the same malignant clone. Consistent with the molecular genetic data, the cytogenetic analyses of the GM-CSF-, IL-3-cultured and the growth factor-independent leukemic cells showed the presence of multiple, closely related abnormal clones, all of which had an interstitial deletion of part of the long arm of chromosome 6 and a complex 1;10;12 translocation. In conclusion, these data demonstrate the involvement of a multipotent leukemic precursor cell in this predominantly mature CD2+ CD3+ CD5+ CD7+ WT31+ T-ALL. This multipotent leukemic precursor may be susceptible to various growth factors and respond with ordered differentiation and maturation.