Trisomy 12 in B‐cell chronic lymphocytic leukaemia: assessment of lineage restriction by simultaneous analysis of immunophenotype and genotype in interphase cells by fluorescence <i>in situ</i> hybridization

Garcíga-Marco, J.; Matutes, Estella; Morilla, Ricardo; Ellis, J.; Oscier, David; Fantes, Judith A.; Catovsky, Daniel; Price, CJ

doi:10.1111/j.1365-2141.1994.tb04868.x

Cited by 38 publications

(13 citation statements)

References 25 publications

(11 reference statements)

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“…In case 3, trisomic cells were present in only 3% of the B cells. This supports previously reported results indicating that only a small proportion of neoplastic cells contains the clonal aberration (Autio et al, 1987;Pérez Losada et al, 1991;García-Marco et al, 1994).…”

Section: Discussionsupporting

confidence: 82%

Optimized mitogen stimulation induces proliferation of neoplastic B cells in chronic lymphocytic leukemia: significance for cytogenetic analysis

Larramendy

Siitonen²,

Zhu³

et al. 1998

Cytogenet Genome Res

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We tested the effects of interleukin-2 (IL-2), human recombinant tumor necrosis factor alpha (TNF-α), Staphylococcus aureus Cowan I (SAC), TPA, and their combinations, using a standard thymidine incorporation assay, in order to identify an optimal mitogen combination (OMC) for 24 consecutive patients with B-cell chronic lymphocytic leukemia (B-CLL). The combination that induced the highest thymidine incorporation was chosen as the OMC for each patient. Among 14 mitogen combinations tested, there were six different OMCs, of which the most frequent was TNF-α + IL-2. It was the OMC in 9 of 24 cases. The other OMCs were TNF-α + TPA1 (5/24), SAC + IL-2 (5/24), TPA1 + IL-2 (3/24), TPA10 + IL-2 (1/24), and TNF-α + TPA10 + IL-1 (1/24). The mitogenic power of the selected OMC in each case was then evaluated both by the combination of immunophenotyping and molecular cytogenetic techniques known as MAC (Morphology, Antibody, Chromosomes) and standard chromosome analysis. After OMC stimulation, the levels of DNA synthesis and B-cell proliferation (mitotic index) were, on average, 10-fold higher than those observed after standard TPA stimulation (P < 0.0001). The proportion of mitotic B cells exceeded the proportion of mitotic T cells in 70.1% of the cases after OMC stimulation. After TPA stimulation, 7.7% ± 2.5% of all mitoses were B-cell mitoses, whereas after OMC stimulation this proportion rose to 57.9% ± 5.3%. The frequency of clonal chromosomal aberrations increased from 46% after TPA stimulation to 79% after OMC stimulation. The clonal aberrations del(6q), del(11q), and/or del(13q) were observed in 26%, 32%, and 42% of the patients with the respective clonal chromosomal aberrations, whereas the corresponding frequencies after TPA stimulation were only 4%, 21%, and 17%. When the lineage involvement of cells with clonal chromosomal aberrations from three patients was analyzed, the aberrations were found to be restricted to B cells only, and in one patient to a minor subset of B cells. The results demonstrate that an individually chosen OMC induces a high rate of proliferation in neoplastic B cells. We found deletions in 6q, 11q, and 13q at higher frequencies than reported previously, most probably as a result of an improved mitogenic response. The identification of an optimal mitogen stimulation for each patient, prior to chromosome analysis, can well be expected to reduce the rate of false-normal results in the future. This is essential for accurate evaluation of the prognostic significance of chromosomal aberrations in B-CLL.

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Section: Discussionsupporting

confidence: 82%

Optimized mitogen stimulation induces proliferation of neoplastic B cells in chronic lymphocytic leukemia: significance for cytogenetic analysis

Larramendy

Siitonen²,

Zhu³

et al. 1998

Cytogenet Genome Res

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“…Trisomy 12 was present in only a proportion of immunotypically clonal cells. The results suggest that although + 12 may represent a primary karyotypic change it proba bly occurs in an already neoplastic B cell population [30], Considering the prognostic implications of +12 (see be low) it makes clinical sense that this abnormality, which is associated with poor morphology and CLL/PL, should be associated with a change in the natural history of CLL.…”

Section: Lineage Restrictionmentioning

confidence: 99%

The Impact of Molecular Cytogenetics on Chronic Lymphoid Leukaemia

et al. 1997

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Chronic lymphoid leukaemias are clonal expansions of B and T cells with mature membrane phenotype. Cytogenetic study of these cases usually requires mitogenic stimulation and can often be hindered by a lack of response of the tumour cells to mitogen, poor quality metaphases, complex markers and proliferation of normal cells. In situ hybridisation with fluorescence-labelled chromosome-specific centromeric DNA probe, single or low copy sequences and whole chromosome paints which hybridise to complementary sequences allow the detection of numerical and structural abnormalities on metaphase and interphase cells with much greater efficiency. Comparative genomic hybridisation uses whole genomic tumour DNA as probe which is hybridised to normal metaphases. It is particularly useful for detecting chromosomal changes without being dependent on the dividing tumour cells. The application of these techniques to the investigation of chronic lymphoid leukaemias is reviewed with emphasis on the work done in our laboratory on trisomy 12 and the tumour suppressor region 13q14 in chronic lymphocytic leukaemia, translocation t(11;14) (q13;q32) in mantle cell lymphoma and other chronic B cell leukaemias, inv(14) (q11q32), i(8q) and complex markers in T prolymphocytic leukaemia.

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“…CLL is unique among B cell malignancies: although multiple chromosomal abnormalities exist in Ϸ50% of all patients (1), no single translocation predominates. Trisomy 12 and deletions of chromosome 13 (13q14) each occur in 20-30% of CLL patients, but these lesions are seen in only a portion of a patient's B cells, indicating that they likely are secondary events (2)(3)(4). Deletions in p53 occur late in CLL in a minority of patients and correlate with aggressive transformation (5).…”

mentioning

confidence: 99%

Aberrant B cell receptor signaling fromB29(Igβ,CD79b) gene mutations of chronic lymphocytic leukemia B cells

Gordon¹,

Kato²,

Lansigan³

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

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Chronic lymphocytic leukemia (CLL) B cells characteristically exhibit low or undetectable surface B cell receptor (BCR) and diminished responses to BCR-mediated signaling. These features suggest that CLL cells may have sustained mutations affecting one or more of the BCR proteins required for receptor surface assembly and signal transduction. Loss of expression and mutations in the critical BCR protein B29 (Ig␤, CD79b), are prevalent in CLL and could produce the hallmark features of these leukemic B cells. Because patient CLL cells are intractable to manipulation, we developed a model system to analyze B29 mutations. Jurkat T cells stably expressing , , and mb1 efficiently assembled a functional BCR when infected with recombinant vaccinia virus bearing wild-type B29. In contrast, a B29 CLL mutant protein truncated in the transmembrane domain did not associate with or mb1 at the cell surface. Another B29 CLL mutant lacking the C-terminal immunoreceptor tyrosine activation motif tyrosine and distal residues brought the receptor to the surface as well as wild-type B29 but showed significant impairment in anti-IgM-stimulated signaling events including mitogen-activated protein kinase activation. These findings demonstrate that B29 mutations previously identified in CLL patients can affect BCR-dependent signaling and may contribute to the unresponsive B cell phenotype in CLL. Finally, the features of the B29 mutations in CLL predict that they may be generated by somatic hypermutation. C hronic lymphocytic leukemia (CLL) is the most common leukemia in the Western world, but the genetic events leading to this disease remain unknown. CLL patients typically accumulate CD5 ϩ , nonresponsive, growth-arrested B cells that express little or no surface Ig. CLL is unique among B cell malignancies: although multiple chromosomal abnormalities exist in Ϸ50% of all patients (1), no single translocation predominates. Trisomy 12 and deletions of chromosome 13 (13q14) each occur in 20-30% of CLL patients, but these lesions are seen in only a portion of a patient's B cells, indicating that they likely are secondary events (2-4). Deletions in p53 occur late in CLL in a minority of patients and correlate with aggressive transformation (5). Bcl2 expression is elevated in CLL B cells in the absence of Bcl2 gene rearrangements (5) and is correlated with promoter hypomethylation (6). Increased Bcl2 expression has been shown to protect B cells against apoptosis in a transgenic mouse (7,8) and could prolong B cell survival, leading to the peripheral accumulation of noncycling B cells in CLL. Impaired B-cell receptor (BCR) signaling has been documented in CLL B cells (9-11). Altered Src family (11) or Syk (10) tyrosine kinase function may contribute to the decreased protein tyrosine phosphorylation and calcium flux exhibited by selected CLL B cell populations (9). However, none of these defects are likely to account for the reduction in surface BCR that is a hallmark of CLL.B29 and the associated transmembrane protein mb1 are crucial for the a...

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Trisomy 12 in B‐cell chronic lymphocytic leukaemia: assessment of lineage restriction by simultaneous analysis of immunophenotype and genotype in interphase cells by fluorescence in situ hybridization

Cited by 38 publications

References 25 publications

Optimized mitogen stimulation induces proliferation of neoplastic B cells in chronic lymphocytic leukemia: significance for cytogenetic analysis

Optimized mitogen stimulation induces proliferation of neoplastic B cells in chronic lymphocytic leukemia: significance for cytogenetic analysis

The Impact of Molecular Cytogenetics on Chronic Lymphoid Leukaemia

Aberrant B cell receptor signaling fromB29(Igβ,CD79b) gene mutations of chronic lymphocytic leukemia B cells

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