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A lineage switch in acute monocytic leukemia. A case report.

A case of congenital monocytic leukemia that underwent a lineage switch to acute lymphocytic leukemia (ALL) is described. The original leukemia had typical monocytic features, as evidenced by morphology (FAB M5), cytochemistry (nonspecific esterase) and immunophenotype (My4 positive). Cytogenetic study showed a pseudodiploid clone t(9;11)(p22;q21) that could be interpreted as a variant of the t(9;11)(p22;q23) reported in patients with the M5 type of leukemia. After successful remission induction with single-agent chemotherapy (VM-26) and subsequent sustained remission for 12 months with alternating VM-26 and VP-16-213, lineage switch to ALL (FAB L1) occurred. The presence of both lymphoid and myeloid markers on leukemic cells at lineage switch suggested the biphenotypic character of the patient's ALL. Our observation indicates that a lineage switch can occur from monocytic leukemia to ALL, although most of the cases previously reported have been in the reverse direction. This case emphasizes again the need to carry out careful and comprehensive marker studies to gain insight into the possible prognostic significance and the application of appropriate therapy.

Bone Marrow↗

Lineage promiscuity in hemopoietic differentiation and leukemia.

An increasing number of reports document instances in which individual leukemic cells coexpress markers normally believed to be restricted to a single lineage. This has been interpreted by McCulloch and colleagues as aberrant programming or lineage infidelity and contrasts with earlier suggestions that lineage fidelity of gene expression was usually maintained in leukemia. We argue that several examples of infidelity are suspect on technical grounds, whereas others are bona fide and require explanation, eg, partial rearrangements and expression of Ig heavy-chain and/or T cell receptor genes in inappropriate cells and terminal deoxynucleotidyl transferase in leukemic myeloblasts. Individual examples of truly aberrant gene expression may well occur in leukemia but with insufficient regularity to be of general significance. We suggest that verifiable and consistent examples of apparent lineage infidelity do not reflect genetic misprogramming but rather the existence of a transient phase of limited promiscuity of gene expression occurring in normal biopotential or multipotential progenitors and able to be preserved as a relic in leukemic blast cell populations that are in maturation arrest. This alternative explanation has interesting implications for mechanisms of hematopoietic differentiation and leads to some testable predictions.

Animals↗

Volume regulation in leukemic and lymphoma cells in children and determination of cell lineage.

Among normal lymphocytes, T cells can readjust their volume rapidly following initial swelling in a hypotonic medium, whereas B cells do not have this ability. Based on this finding, we examined the volume regulation of malignant cells from 40 patients with lymphocytic and nonlymphocytic malignancies. The T lineage cells were able to regulate their volume in response to hypotonic stress, whereas B lineage cells were not able to do so. In contrast to lymphoid lineage cells, nonlymphocytic leukemia cells as well as undifferentiated cells did not show a consistent tendency in their volume regulation. These results showed that the difference in the ability to regulate cell volume in response to hypotonic stress is available as a marker for identifying the cellular lineage of lymphoid malignancies.

Acute Disease↗

Marrow purging in autologous bone marrow transplantation for T-lineage acute lymphoblastic leukemia: efficacy of ex vivo treatment with immunotoxins and 4-hydroperoxycyclophosphamide against fresh leukemic marrow progenitor cells.

A lymphoblast progenitor cell assay was used to evaluate the antileukemic efficacy of marrow-purging protocols that employed intact ricin immunotoxins (IT) and 4-hydroperoxycyclophosphamide (4-HC) against clonogenic primary T-lineage marrow blasts freshly obtained from 12 T-lineage acute lymphoblastic leukemia (ALL) patients. Residual T-lineage blast colonies were observed after treatment with 1 micrograms/mL T101 (anti-CD5)-Ricin (R) + G3.7 (anti-CD7)-R in eight of 12 cases and after 100 micrograms/mL 4-HC in six of nine cases. By comparison, a combination of IT and 4-HC proved very effective against T-lineage leukemic progenitor cells, and no residual blast colonies were observed in any of the eight cases studied. We conclude that future trials should consider combined treatment protocols such as IT + 4-HC for more effective purging of autologous marrow grafts.

Antibodies, Monoclonal↗

Use of colony assays and anti-T cell immunotoxins to elucidate the immunobiologic features of leukemic progenitor cells in T-lineage acute lymphoblastic leukemia.

The specific binding of radioiodinated rIL-2 to fresh marrow blasts from T-lineage acute lymphoblastic leukemia (ALL) patients was initially investigated. The estimated number of radioiodinated rIL-2 molecules bound per blast ranged from undetectable to 1948. In colony assays, 72% of 32 cases analyzed showed a significant proliferative response to rIL-2, which depended on PHA-stimulated lymphocyte conditioned medium activation. Colony stimulation indices correlated with the number of radioiodinated rIL-2 molecules bound per blast but not with expression of CD25/Tac Ag on fresh marrow blasts or primary colony blasts. These findings provide evidence that in T-lineage ALL functional IL-2R proteins are expressed on leukemic progenitor blasts which may be distinct from Tac Ag. We used the mAb 35.1, T101, and G3.7 to test for expression of CD2, CD5, and CD7 on fresh marrow blasts from 126 T-lineage ALL patients. CD2, CD5, and CD7 were expressed in 84%, 93%, and 99% of cases, respectively. Furthermore, colony blasts that represent the early progeny of leukemic progenitor blasts were also CD2+CD5+CD7+. Ricin conjugates of 35.1, T101, and G3.7 mAb were used as Ag-specific cytotoxic probes to test for expression of CD2, CD5, and CD7 at the level of T-lineage leukemic progenitor blasts. Each immunotoxin was able to selectively eliminate greater than 99% of leukemic progenitor blasts, providing unique and direct evidence that these cells co-express CD2, CD5, and CD7. Neither mixtures of anti-CD5 and anti-CD7 nor anti-CD2, anti-CD5, and anti-CD7 immunotoxins were more effective against blast progenitor cells than the individual immunotoxins alone, confirming that CD2, CD5, and CD7 are not expressed on non-overlapping progenitor cell subpopulations.

Antibodies, Monoclonal↗

c-sis but not c-fos gene expression is lineage specific in human myeloid cells.

Expression of both the c-fos and c-sis protooncogenes during myeloid differentiation has been detected in cells of the monocytic lineage. Since an increase in c-fos transcripts was not detected during dimethylsulfoxide induced HL-60 granulocytic differentiation, it was suggested that within the myeloid series c-fos gene expression might be lineage specific. In the present study, we have determined whether expression of the c-fos and c-sis genes is indeed specific for the monocytic pathway or rather common to both the granulocyte and monocyte pathways. C-fos and c-sis gene expression was analyzed in freshly isolated human granulocytes and monocytes, in human HL-60 promyelocytic leukemia cells induced to differentiate along the granulocytic or monocytic pathway, in myeloblasts from five patients with the M1 or M2 subtype of acute myeloblastic leukemia (AML) and in blasts from six patients with M4 myelomonocytic leukemia. The level of c-fos mRNA was fifteen times higher in granulocytes as compared with monocytes. An increase in c-fos expression was also found in HL-60 cells differentiated along the granulocytic pathway after exposure to hypoxanthine, hexamethylene bisacetamide, and the combination of retinoic acid and dibutyryl adenosine 3'5' cyclic monophosphate. Three of 5 M1 and M2 leukemic myeloblast preparations depleted of lymphoid and monocytic cells and all six M4 leukemic cells expressed c-fos transcripts. In contrast, c-sis gene transcripts were detectable in monocytes and during drug induced monocytic differentiation of the HL-60 cells but not in granulocytes during granulocytic differentiation of the HL-60 cells or in AML samples. Thus, in the myeloid series, c-sis gene expression is lineage specific while expression of the c-fos gene is found in both lineages and may be related to metabolic pathways common to both granulocytes and monocytes.

Actins↗

Characteristic distribution density of organelles in the cytoplasm of respective kinds of cell lineages of ascidian embryos.

In the early embryos of the ascidian (Halocynthia roretzi), regional cytoplasmic differences arise just after fertilization. We successively studied the characteristic features of the cytoplasm of those regions in the embryonic cells during the entire ontogenic process from the unfertilized egg to the tadpole larva. The embryos and larvae were fixed in a mixture of osmium and glutaraldehyde, and the distribution of the organelles in the entire cytoplasm was observed with light and electron microscopy. According to the analysis of the distribution density of the organelles which occupied a given area of the cytoplasm on the section, we introduced the "organelle region" in the cytoplasm and further calculated the approximate area ratios of the "organelle regions" in the cytoplasm of each cell lineage. As a result, it was demonstrated that the characteristic distribution mode was already present in the cytoplasm of the cell lineages of the 8-cell-stage embryos. The features of the cytoplasm in each embryonic cell lineage, moreover, reflected those of the corresponding larval tissue. Our results not only demonstrate that the structural tissue specificity is expressed at an extremely early stage during the ascidian embryogenesis but also suggest that the corresponding functional differentiation among the cell lineages occurs early.

Animals↗

Establishment of eosinophilic sublines from human promyelocytic leukemia (HL-60) cells: demonstration of multipotentiality and single-lineage commitment of HL-60 stem cells.

Recent observations indicating that the HL-60 human acute promyelocytic leukemia cell line contains a minor eosinophil population in addition to neutrophil and mononuclear phagocyte progenitors suggest the multipotentiality of HL-60 stem cells. In order to clarify multilineage differentiation and commitment to single-lineage progenitors we analyzed HL-60 colonies formed in methylcellulose. In an HL-60 parent line with a relatively high eosinophil content (5.5%), 36% of the spontaneous colonies consisted partly or wholly of eosinophilic cells. After two rounds of subcloning in methylcellulose, two eosinophilic sublines and two neutrophilic sublines were established. These lines have been in continuous liquid culture for more than four months, and they show stable single-lineage differentiation. Purified biosynthetic GM-CSF, which stimulates normal CFU-GM and CFU-EO, induced monocytic differentiation but no eosinophilic differentiation in the neutrophilic sublines and no neutrophilic or monocytic differentiation in the eosinophilic sublines. These observations indicate that HL-60 stem cells are multipotent and capable of spontaneous commitment to single-lineage progenitors. The eosinophilic HL-60 sublines should facilitate studies on the production and function of human eosinophils and the single-lineage sublines will allow further analysis of leukemic cell differentiation and stem cell commitment.

Cell Differentiation↗

Discordant expression of CD3 and T-cell receptor beta-chain antigens in T-lineage lymphomas.

Using an immunoperoxidase technique that identifies both surface and cytoplasmic antigen expression, the authors examined 28 benign reactive lymphorproliferative lesions and 55 T-lineage lymphomas for reactivity with CD3 (Leu-4; T-cell receptor-associated antigen) and beta F1 antibodies, the latter recognizing nonpolymorphic determinants on T-cell receptor beta chains. Consistent with previous observations that these two antigens are co-expressed on the vast majority of thymocytes, peripheral blood T cells and tonsillar T cells, all 28 reactive lymphoproliferations showed essentially identical patterns of CD3 and beta F1 expression. In contrast, only 29 of 55 T-lineage lymphomas displayed coexpression of these antigens. Among 33 peripheral T-cell lymphomas, 11 cases showed CD3/beta F1 discordance (7 CD3+/beta F1-; 4 CD3-/beta F1+), and 5 showed absence of both these antigens. Nine of 22 T-lymphoblastic lymphomas showed CD3/beta F1 discordance (all CD3+/beta F1-), and 1 case was CD3-/beta F1-. These patterns of CD3/beta F1 expression, along with the patterns of CD2, CD4, CD5, CD7, and CD8 antigen expression in these neoplasms, indicate that T-cell lymphomas can manifest phenotypes not apparently reflective of normal T populations and suggest the presence of abnormal gene expression in these malignancies. The existence of aberrant phenotypes in T-cell neoplasia suggests caution in interpretation of investigations using T-lineage malignancies as models of normal T-cell biology. Finally, the identification of phenotypic abnormalities in T-lineage populations can be of great diagnostic usefulness in the delineation of benign versus malignant T-cell proliferations.

Antigens, Differentiation, T-Lymphocyte↗

Bone marrow cytogenetics: the lineage of dividing cells changes during the first few hours in culture.

To determine changes in the cell lineages of metaphases karyotyped following different culture times, marrow from 11 healthy individuals was studied using a technique that allows simultaneous analysis of karyotype and cell lineage. Cell lineage was identified as erythroid by surface glycophorin A, granulocytic by Sudan black B and PM-81, and monocytic by lysozyme. Marrow examined sequentially showed granulocytic mitoses to initially decrease from a mean of 40% at 1.75 hr to 6% at 3.5 hr and then increase, being 46% by 6 hr and 82% after 1 day, and remain high for the 10 days studied. Erythroid mitoses were most frequent (mean, 72%) at 3.5 hr and then decreased rapidly, being 16% by 6 hr, 7% at 1 day, and absent thereafter. When granulocytic mitoses were least frequent, 20-36% of mitoses were also unreactive with glycophorin A. Double staining experiments to identify these cells found some to be monocytic, but most remained unidentified. The authors conclude that mitoses of different hematopoietic lineages predominate when normal marrow is studied cytogenetically at different times following aspiration, and that the major changes occur during the first 8 hours. These findings have importance for how cytogenetic studies are performed in leukemia.

Adult↗

p53 gene inactivation in acute lymphoblastic leukemia of B cell lineage associates with chromosomal breakpoints at 11q23 and 8q24.

The clinical heterogeneity of acute lymphoblastic leukemia (ALL) of B cell lineage reflects the presence of distinct molecular pathways leading to well-defined ALL molecular subtypes. These molecular pathways include the formation of the fusion transcripts BCR/ABL and E2A/PBX1, due to t(9;22) and t(1;19), respectively, as well as rearrangements of the MLL gene at 11q23 and of c-MYC at 8q24. Hyperdiploid ALL in the absence of chromosomal structural abnormalities is an additional ALL molecular subtype. Mutations of the RAS family genes and of the p53 tumor suppressor gene represent additional genetic lesions detected in a fraction (10-20%) of ALL cases. RAS activation in ALL may be detected in all molecular subtypes of ALL and denotes poor prognosis. Conversely, little is known regarding the clinical and biological features of ALL cases carrying p53 mutations. In order to help clarify the role of p53 inactivation in ALL development, we have determined the frequency of p53 mutations throughout the molecular spectrum of B cell lineage ALL. We report that p53 inactivation in ALL of B cell lineage is restricted to cases carrying a rearrangement of MLL or c-MYC, whereas it is consistently negative in other molecular subgroups. These data underline the molecular heterogeneity of ALL of B cell lineage and indicate that at least some of the molecular pathways involved in ALL pathogenesis require more than one genetic lesion.

Base Sequence↗

Lineage-specific alternative splicing of the human Fc gamma RIIA transmembrane exon requires sequences near the 3' splice site.

The human Fc gamma RIIA gene produces multiple transcripts, including those with (Fc gamma RIIa1) and without (Fc gamma RIIa2) the single exon encoding the transmembrane domain (TM). Previously, a fluorescence-based RT-PCR assay showed lineage-specific differences in Fc gamma RIIA transcript ratios (Fc gamma RIIa2/Fc gamma RIIa1). The mechanism of this lineage-specific expression was investigated in this study. Differential transcript stability does not play a major role, because transcript ratios remained constant in cells with both low (K562) and high (Dami) ratios following actinomycin D treatment. Transient expression studies in K562 and Dami cells using a minigene construct containing a 5.0 kb genomic fragment including the TM exon and adjacent intron and exon sequences showed recapitulation of endogenous transcript ratios. The TM exon was efficiently spliced in by the constitutive splicing machinery in HeLa cells, an Fc gamma RIIA-negative cell line. Lineage-specific TM exon skipping was markedly diminished by two independent minigene mutations: a point mutation of the first nucleotide of the TM exon, and a five basepair intronic deletion near a putative branchpoint. These data demonstrate that cis-acting sequences in or near the TM exon 3' splice acceptor site contribute to lineage-specific differences in Fc gamma RIIA transcript ratios.

Alternative Splicing↗

Use of polyclonal anti-myeloperoxidase antibody in myeloid lineage determination.

This study reports the production of a rabbit polyclonal antibody to myeloperoxidase (MPO) and its use in ascertaining the myeloid lineage of blasts in leukaemia. Comparison of the immunocytochemical stain using the anti-MPO antibody with the routine cytochemical methodology showed that the former was more sensitive. In all subtypes of acute myeloid leukaemia (AML; 72 patients, M1-M6) greater number of MPO positive blast cells were observed by immunocytochemistry, the highest being in the promyelocytic leukaemia. It was also extremely specific for cells of the myeloid lineage as it did not react with blasts from acute lymphoblastic (50 patients) and megakaryoblastic leukaemias (1 patient). In addition, it proved most useful for the lineage determination of blasts from patients with undifferentiated acute leukaemias (AUL) and those with chronic myeloid leukaemia in blast crisis (CML-BC). Out of 8 patients of AULs, 6 were classified as acute myeloblastic leukaemia due to their reactivity to the anti-MPO antibody. Similarly, out of 12 patients of chronic myeloid leukaemia in blast crisis, blasts from 8 showed reactivity to this antibody and thus could be identified as belonging to the myeloid lineage and/or of the mixed blast crisis type.

Blast Crisis↗

Thymic development in human CD4 transgenic mice. Positive selection occurs after commitment to the CD8 lineage.

Developing T cells are positively selected on the basis of their recognition of polymorphic MHCs (major histocompatibility molecules). The CD4 and CD8 co-receptors, together with a compatible TCR-alpha beta, bind class II and class I MHC, respectively, delivering a signal that allows T cell maturation to proceed along the appropriate co-receptor lineage. During development, thymocytes first co-express CD4 and CD8 and subsequently commit to a single co-receptor phenotype. Debate exists over the stage at which positive selection occurs. Positive selection may precede or accompany co-receptor lineage commitment or occur subsequent to the acquisition of a single co-receptor phenotype. We developed transgenic (TG) mice expressing human CD4 (huCD4) on T cells. To study differentiation of CD8+ cells, huCD4 TG mice were bred with mice lacking class I MHC (class I-). This enabled us to assess maturation of mCD8+mCD4+huCD4+ thymocytes to mCD8+mCD4-huCD4+ cells after interaction between huCD4 and mclass II MHC. In the absence of huCD4, class I- mice failed to produce mCD8+ cells. However, expression of huCD4 allowed development of mCD8+mCD4-huCD4+ T cells, suggesting that selection of cells precommitted to the mCD8+mCD4- lineage occurred. Importantly, CD8+ T cells were increased in both the thymus and the periphery of huCD4 TG x class I- animals, indicating their intrathymic origin. V beta 14+ CD8+ T cells were also increased, as predicted for positive selection of CD8+ cells bearing class II-reactive TCRs. These data provide evidence that positive selection occurs at a late stage of thymocyte differentiation, after commitment to the CD8 lineage.

Animals↗

Molecular diagnostic testing for determination of myeloid lineage in acute leukemias.

Determination of myeloid vs. lymphoid cell lineage in acute leukemias is essential for diagnosis, prognosis, and treatment. However, some leukemic cells are too primitive to be identified based on conventional morphology, cytochemistry, and immunophenotype criteria. The gene for myeloperoxidase (MPO) is central to the lineage designation of myeloid cells and their function. Expression of MPO messenger ribonucleic acid (mRNA) may serve to determine the myeloid lineage of primitive leukemic cells that do not express the final product, MPO. Recently, a procedure has been developed for detection of MPO mRNA in leukemic cells, based on message amplification by reverse transcription-polymerase chain reaction (RT-PCR). Three variant polymerase chain reaction (PCR) methods, developed in view of future diagnostic applications of the RT-PCR procedure are reported: (A) nested PCR, using a second pair of internal primers for reamplification of the first PCR product; (B) multiplex PCR for concomitant amplification of up to seven sequences encompassing all regions of MPO mRNA; (C) adaptation of the standard PCR procedure and the two variant methods for use of cellular material from air-dried unstained or Wright stained smears. These variant procedures developed on the HL-60 cell line make the RT-PCR detection of MPO mRNA easily applicable as a new diagnostic test in acute leukemias and confer the versatility needed in the clinical setting. The advantages of our new procedure for MPO mRNA detection are: high sensitivity and specificity, speed, simplicity, and safety. Myeloid lineage of leukemic blasts can be established, confirmed, or ruled out in 6 to 10 hours, making results available at the time of bone marrow sign-out.(ABSTRACT TRUNCATED AT 250 WORDS)

Actins↗

Candidate tumor-suppressor genes MTS1 (p16INK4A) and MTS2 (p15INK4B) display frequent homozygous deletions in primary cells from T- but not from B-cell lineage acute lymphoblastic leukemias.

Using a Southern blot approach, deletions of MTS1 (multiple tumor-suppressor gene 1) and MTS2 (multiple tumor-suppressor gene 2) candidate tumor-suppressor genes have been studied in primary neoplastic cells from 55 acute lymphoblastic leukemia (ALL) patients. Homozygous MTS1 deletions were found in 20 of 24 T-ALL cases and in only 2 of 31 B-lineage cases (P < .001). The deletions involved MTS1 and MTS2 in most cases. Homozygous MTS2 deletions were observed in 16 of 24 T-ALL cases and in 1 of 31 B-lineage ALLs (P < .001), all of them displaying homozygous MTS1 deletions. In 5 cases (4 T and 1 B), deletions involved MTS1 but spared the MTS2 gene, showing that one deletion breakpoint was located between the two genes within a 25-kb region. In 1 T-ALL case, an MTS1 gene rearrangement has occurred downstream to exon 2. Possible hemizygous deletions were found in 6 cases, 4 of them of the B-cell lineage. In 7 ALL cases, cells obtained at presentation and at first relapse were studied and identical results were observed in 6 cases. In 1 B-lineage case, a germline pattern was found at presentation and a possible monoallelic MTS1/MTS2 deletion was observed at relapse. The high frequency of MTS1 and MTS2 homozygous deletions in T-ALLs supports the view that inactivation of these genes plays an important role in the pathogenesis of this type of human leukemia.

Adolescent↗

Making sense of cell lineage.

In this article I describe what I see as the sources of confusion in the description and interpretation of cell lineage data. I concentrate on lineage in the nervous system, since that is my interest, but most of the arguments are broadly applicable. Since there are these differences between workers in the field, all will not agree with my perspective, but perhaps a consensus can evolve from the discussion. I see the problem as having two facets: First, there is a confusion surrounding terminology, which leads to too many different types of studies to be considered as studies of cell lineage; and second, there is some confusion about what can validly be concluded from a study of cell lineage.

Animals↗

Use of transgenic mice to study regulation of gene expression in the parietal cell lineage of gastric units.

The mechanisms that regulate cell lineage-specific and differentiation-dependent patterns of gene expression in the gastric units of the stomach are largely unknown. Transgenic mice were generated in order to identify cis-acting sequences that determine the zymogenic cell-specific pattern of expression of the mouse intrinsic factor (InF) gene and the parietal cell-specific pattern of expression of the mouse H+/K(+)-ATPase beta-subunit gene. Portions of the 5'-nontranscribed domains of each gene were linked to the human growth hormone (hGH) gene beginning at its nucleotide +3. RNA blot hybridization studies combined with multilabel immunocytochemical surveys using a panel of lineage-specific antibodies and lectins indicated that nucleotides -1035 to +24 of the mouse H+/K(+)-ATPase beta-subunit gene direct a pattern of reporter production which recapitulates the parietal cell-specific and developmental patterns of expression of the endogenous gene. Analysis of three mosaic founders containing H+/K(+)-ATPase beta-subunit-1035 to +24/hGH+3 revealed that they had monophenotypic gastric units: a given unit contained either a wholly hGH-positive or a wholly hGH-negative population of parietal cells. These latter findings provide very strong evidence that gastric units are monoclonal, i.e. they are supplied by stem cells having one genotype. Although some, but not all, parietal cells are apparently derived from the same committed progenitor as zymogenic cells, virtually all parietal cells in a given gastric unit, but none of its zymogenic cells, express InF-1029 to +55/hGH+3. This suggests that InF-1029 to +55 may contain cis-acting sequences which allow parietal cell expression in other species (e.g. humans) but lack additional elements which normally function in mice to suppress InF expression in this lineage. The absence of hGH in zymogenic cells also means that the transcriptional regulatory environments of parietal and zymogenic cells derived from the same precursor are distinguishable by InF-1029 to +55. H+/K(+)-ATPase beta-subunit-1035 to +24 and InF-1029 to +55 are the only two sequences reported to date that are able to direct foreign gene expression exclusively to a gastric epithelial cell lineage in transgenic mice. This ability to deliver gene products to parietal cells can now be exploited to identify factors that control their normal proliferation and differentiation programs and/or to specifically alter their biological properties.

Amino Acid Sequence↗