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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Presenting features of 120 consecutive children with T-cell acute lymphoblastic leukemia (ALL), representing 15% of all patients diagnosed as having ALL during the study period, were analyzed to determine relationships with treatment outcome. Patients' ages ranged from 1.7 to 18.8 years (median, 10.3 years) and their leukocyte counts from 1.7 to 1,070 x 10(9)/L (median, 100 x 10(9)/L). Central nervous system (CNS) leukemia was present in 12.5% of the cases, a mediastinal mass in 61%, and L2 lymphoblast morphology in 32%. A relatively high proportion of cases, 26%, had normal karyotypes at presentation. Of the cases tested, membrane CD1 expression was found in 38% of cases, CD3 in 33%, CD4 in 50%, CD5 in 94%, CD8 in 55%, and CD10 in 35%. Four presenting features were found to confer an increased risk of treatment failure: age greater than or equal to 15 years, L2 lymphoblast morphology, abnormal karyotype, and membrane CD3 expression. This study illustrates the heterogeneity of presentations of childhood T-cell ALL and suggests that the relative importance of risk factors in ALL differs according to immunophenotype and treatment strategy.
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PMID:Heterogeneity of presenting features and their relation to treatment outcome in 120 children with T-cell acute lymphoblastic leukemia. 213 2

Human T-cell leukemia and T-cell acute lymphoblastic leukemia cell lines were studied for alterations in the p53 tumor suppressor gene. Southern blot analysis of 10 leukemic T-cell lines revealed no gross genomic deletions or rearrangements. Reverse transcription-polymerase chain reaction analysis of p53 mRNA indicated that all 10 lines produced p53 mRNA of normal size. By direct sequencing of polymerase chain reaction-amplified cDNA, we detected 11 missense and nonsense point mutations in 5 of the 10 leukemic T-cell lines studied. The mutations are primarily located in the evolutionarily highly conserved regions of the p53 gene. One of the five cell lines in which a mutation was detected possesses a homozygous point mutation in both p53 alleles, while the other four cell lines harbor from two to four different point mutations. An allelic study of two of the lines (CEM, A3/Kawa) shows that the two missense mutations found in each line are located on separate alleles, thus both alleles of the p53 gene may have been functionally inactivated by two different point mutations. Since cultured leukemic T-cell lines represent a late, fully tumorigenic stage of leukemic T cells, mutation of both (or more) alleles of the p53 gene may reflect the selection of cells possessing an increasingly tumorigenic phenotype, whether the selection took place in vivo or in vitro. Previously, we have shown that the HSB-2 T-cell acute lymphoblastic leukemia cell line had lost both alleles of the retinoblastoma tumor suppressor gene. Taken together, our data show that at least 6 of 10 leukemic T-cell lines examined may have lost the normal function of a known tumor suppressor gene, suggesting that this class of genes serves a critical role in the generation of fully tumorigenic leukemic T cells.
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PMID:Frequent mutations in the p53 tumor suppressor gene in human leukemia T-cell lines. 214 11

Cell line PER-315 was established from a bone marrow sample of a 5-year-old boy diagnosed with acute lymphoblastic leukemia (ALL) of T cell lineage. PER-315 cells express the surface markers present on immature thymocytes, express cytoplasmic CD3, and their growth is dependent on interleukin-2 (IL-2). Hence, this cell line represents a new type of precursor T-ALL, which is IL-2 dependent. Assessment of the T cell receptor rearrangements confirmed the clonal origin of cell line PER-315, and comparison with the patient's leukemia cells revealed an identical pattern. PER-315 cells show strong cytotoxicity against cell lines K562, Daudi, and Molt-4. They do not express the Tac antigen, but bind IL-2 with a Kd of 650 pM. Since PER-315 cells represent immature thymocytes, this new cell line may provide a model to further investigate the IL-2 receptor structure present at this stage of T cell differentiation.
Leukemia 1990 Apr
PMID:Characterization of an interleukin-2 dependent human leukemic cell line, PER-315, with an immature T cell phenotype which does not express the tac antigen. 216 20

We studied the organization of immunoglobulin (Ig) genes and the beta-chain gene of the T cell receptor (TCR) along with the clinical features, immunophenotypes, and karyotypes of 14 children with acute leukemia at diagnosis and relapse. The median time to relapse was 23 months. Eleven children had identical gene rearrangement patterns at diagnosis and relapse. All three patients whose blast cells showed variations in gene rearrangement patterns between diagnosis and relapase also demonstrated a change in the immunophenotype: one from cALLA+ to cALLA- B precursor cell ALL; one from T-ALL to AML; and one showed a marked increase in myeloid characteristics at relapse. Blast cells from these three patients at relapse showed the presence of chromosomal translocations involving 11q23; for two patients, this involved replacement of the original karyotype. We conclude that while most relapses are the result of reemergence of the original clone, new clones that differ in immunophenotype, karyotype, and gene rearrangement are occasionally present at relapse. Relapses may also occur in which the original clone has undergone major changes in gene expression and arrangement of the Ig heavy chain genes in the absence of karyotypic replacement.
Leukemia 1990 Nov
PMID:Alterations in immunoglobulin or T cell receptor gene rearrangement at relapse: involvement of 11q23 and changes in immunophenotype. 217 64

In the therapy studies ALL-BFM 83 and 86, immunophenotyping of ALL by monoclonal antibodies was performed in a total of 1162 protocol patients (ALL-BFM 83 n = 578; ALL-BFM 86 n = 584). Both studies yielded similar results with respect to the incidence of immunological subtypes: CD10-negative pre-pre-B ALL (ALL-BFM 83: 3.6%; ALL-BFM 86: 5.3%), common ALL (80.1%; 77.9%), B-ALL (1.9%; 2.8%), pre-T/T-ALL (13.9%; 13.5%). Leukemic cells of 3 patients in the ALL-BFM 83 study lacked lymphoid and myeloid antigens (acute unclassifiable leukemia, 0.5%), and 3 patients in the ALL-BFM 86 study exhibited different blast populations with expression of either myeloid or lymphoid features (acute mixed-lineage leukemia, 0.5%). Coexpression of myeloid antigens (CD13 and/or CD33 and/or CDw65) on lymphoblasts (My-positive ALL) was identified in 35 of the 570 (6.1%) protocol patients prospectively analyzed in the ALL-BFM 86 study. The following associations were observed between the immunological subtype and the clinical risk factors: median age (years)-pre-pre-B 3.0, common 4.3, B- 7.9, pre-T/T-ALL 8.5 (pre-pre-B, common vs. pre-T/T-ALL p = 0.05); median leukocyte counts (x 10(9)/l)-pre-pre-B 80, common 9.1, B- 12.3, pre-T/T-ALL 68.1 (common, B- vs. pre-pre-B, pre-T/T-ALL p less than 0.05). The prognostic relevance of the immunophenotype was evaluated on the basis of the therapeutic results obtained in the ALL-BFM 83 study. A significant difference in the remission rate was only recognizable between patients with common ALL (99.1%) and those with pre-T/T-ALL (93.7%, p less than 0.001). After a median follow-up of 54 months, the probability of event-free survival is 71% for pre-pre-B ALL, 67% for common ALL, 56% for pre-T/T-ALL and 27% for B-ALL (common vs. B-, pre-T/T-ALL p less than 0.001), the prognosis in patients with pre-pre-B and common ALL being markedly influenced by the initial leukocyte counts and the age.
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PMID:[Incidence, clinical markers and prognostic significance of immunologic subtypes of acute lymphoblastic leukemia (ALL) in children: experiences of the ALL-BFM 83 and 86 studies]. 220 38

T-cell acute lymphoblastic leukemia is an aggressive disease that responds poorly to "standard" therapy designed for the more common B-lineage ALLs in childhood. The principles of this "standard" therapy were derived from empiric clinical trials. Thus, it is not surprising that the therapy that had the greatest impact on survival in the group as a whole would be found to be most successful for the most common subset of patients. T-cell malignant lymphoblasts share many biologic features that set them apart from the more common B-lineage lymphoblasts. Some of these biologic features suggest therapeutic approaches that should be particularly successful in treating patients with T-cell leukemia. The use of aggressive, multiple-agent "pulse" chemotherapy has been shown through empiric trials to have relative efficacy in T-cell lymphoblastic leukemia, presumably because of the rapid generation time and high growth fraction. Future studies will (1) determine the optimal dose and schedule of cytosine arabinoside needed to exploit the increased Ara-CTP accumulation in T-cell blasts, (2) determine the efficacy of a new agent, deoxycoformycin, an inhibitor of adenosine deaminase, to exploit the biochemical phenotype of T-cell blasts, and (3) assess the ability of conjugated anti-T monoclonal antibodies to deliver a cytotoxic agent, thus exploiting unique antigenic determinants at the cell surface. As more is learned about the biology of T-cell malignancies, further treatment strategies may be suggested to exploit the new features that are discovered. Similarly, it is hoped that the unique features of the B-lineage leukemias will suggest treatment strategies that will improve survival in those patients as well. Certainly, improved survival has already been achieved in the case of the B-cell leukemias and Burkitt's lymphomas, and improvement may also be possible for the pre-B and early pre-B phenotypes of lymphoblastic leukemia.
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PMID:Treatment of T-lineage acute lymphoblastic leukemia. 226 86

Non-random translocation involving the short arm of chromosome 19 are frequently observed in acute leukemias. Recent studies have shown that the 19p13 genes E2A and LYLl, both of which encode helix-loop-helix proteins, lie at two different translocation breakpoints in acute lymphoblastic leukemias (ALL). The E2A gene is involved by the t(1;19)(q23;p13) in acute pre-B-cell leukemias and the LYL1 gene is structurally altered by a t(7;19)(q34;p13) in T-cell ALL. To assess the role of these genes in other leukemia-associated translocations we mapped their locations with respect to the t(11;19)(q23;p13) and t(4;19)(q21;p13) translocation breakpoints carried by T-ALL cell lines SUP-T13 and SUP-T8a, respectively. In situ hybridization studies indicated that the E2A and LYL1 genes are physically distinct from the t(4;19) and t(11;19) breakpoints. Using these and other 19p13 translocation breakpoints as landmarks, we established a partial physical map of 19p: 19pter-E2A-INSR-LYL1-[t(4;19)]-19cen. These data should help guide molecular studies to further characterize 19p13 breakpoints and mapping of genes in this chromosomal region.
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PMID:Mapping of translocation breakpoints on the short arm of chromosome 19 in acute leukemias by in situ hybridization. 226 76

Cytogenetic studies on 44 patients with T-cell acute lymphoblastic leukemia (ALL) were reported. The incidence of leukemia without detectable chromosomal changes was 25%. Hyperdiploidy with more than 50 chromosomes was found in only one patient. Previously described nonrandom abnormalities like 6q-, 9p-, and 12p- were observed, and it was confirmed that they are not specific for a particular type of ALL. The incidence of chromosomal rearrangements on chromosomes 7 and 14 where the T-cell receptor gene loci are located was 36% of those with abnormal karyotypes and 27% of the total. This was clearly different from the frequency of rearrangements of these bands found in T-cell lymphoma. Finally, a rearrangement on bands 11q14-q21 was detected in five cases.
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PMID:Cytogenetic studies of 44 T-cell acute lymphoblastic leukemias. 229 82

One case of de novo Ph-negative T-cell acute lymphoblastic leukaemia has been found to have a classical breakpoint cluster region (bcr) rearrangement of the type seen in chronic granulocytic leukaemia. There were no haematological features to suggest a previous chronic phase. This case represents the first report of this rearrangement in Ph negative acute T-lymphoblastic leukaemia at presentation. The implications for various therapeutic options in such patients are discussed.
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PMID:De novo Ph negative T-cell lymphoblastic leukaemia associated with bcr gene rearrangement. 230 57

We cloned the t(10;14) recurrent translocation from CD3-negative T-cell acute lymphoblastic leukemia cells. The breakpoint at 14q11 involved an intermediate rearrangement of the delta T-cell receptor locus, suggesting that the translocation arose at the time of antigen receptor assemblage. Translocation introduced chromosome segment 10q24 as proven by hybridization of a breakpoint-derived probe to flow-sorted chromosomes and metaphase chromosomes. Two t(10;14) breakpoints were clustered within a 600-base-pair region of 10q24 but no heptamer-spacer-nonamer motifs resembling T-cell receptor/immunoglobulin rearrangement signals were noted at the breakpoint. A locus distinct from terminal deoxynucleotidyltransferase was found at 10q24. Evolutionarily conserved regions surrounding the 10q24 breakpoint were examined for transcriptional activity. A region telomeric to the 10q24 breakpoint, expected to translocate to the der(14) chromosome, recognized an abundant 2.9-kilobase RNA in a t(10;14) T-cell leukemia. This locus was not active in a variety of other normal and neoplastic T cells, arguing that it was deregulated by the introduction of the T-cell receptor. This locus is a candidate for a putative protooncogene, TCL3, involved in T-cell neoplasia.
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PMID:The t(10;14)(q24;q11) of T-cell acute lymphoblastic leukemia juxtaposes the delta T-cell receptor with TCL3, a conserved and activated locus at 10q24. 232 74


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