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M J Dyer

Publications and source records attributed to M J Dyer.

At least 73 records · Page 4Linked to original sources
PubMed1994

Aberrant rearrangements within the immunoglobulin heavy chain locus in hairy cell leukemia.

The cell surface expression of multiple immunoglobulin heavy chain (IGH) isotypes, preferentially observed in hairy cell leukemia (HCL), is incompatible with the deletion model of IGH class switching, and alternative models involving RNA-splicing have been proposed. To help discriminate between these possibilities we have examined the configuration of the IGH locus by DNA blot in 38 cases of HCL. Deletion of at least one allele of C mu/C delta was seen in 14 cases (37%). Of 12 cases in which IgG and/or IgA were expressed, three exhibited biallelic deletion of C mu/C delta compatible with deletional class-switching whereas the remaining 9 cases retained both alleles of C mu/C delta. These data indicate that both DNA deletion and RNA-splicing mechanisms of class-switching may operate in HCL. In a further 17 cases, other unexpected abnormalities of the IGH locus mapping to the JH-C mu intron in one of two patterns were observed. First, discordance between JH and C mu in BamHI DNA digests was found in 12 cases. Similar patterns were observed in only 4/91 cases of B-cell chronic lymphocytic leukemia and 0/15 of B-cell prolymphocytic leukemia. To preclude chromosomal translocations involving the JH-C mu intron, rearrangements of BCL1, BCL2, BCL3, and MYC were sought in 23 cases but none of the cases showed oncogene rearrangement to the intron. Second, abnormal-sized C mu fragments arising as a consequence of abnormalities of the JH-C mu intron were detected in HindIII, BgIII, and/or Xbal digests in 10/23 cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗
PubMed1994

BCL-1/cyclin D1 oncoprotein oscillates and subverts the G1 phase control in B-cell neoplasms carrying the t(11;14) translocation.

In an effort to elucidate the biological role played by cyclin D1, a candidate BCL-1 oncogene, in human B-cell tumours carrying the t(11;14) translocation, we have studied the properties of this cyclin protein in a series of human lymphoid lines with rearrangements in the BCL-1 locus. The BCL-1/cyclin D1 protein was easily detectable in both immunocytochemistry and immunoblotting, its abundance grossly correlating with the mRNA levels. The cyclin D1 protein was localised predominantly to nuclei and there was a striking variation of staining intensity among the exponentially growing cells, reflecting the maximum level reached in mid/late G1 and the lowest level in S-phase. This characteristic mode of cell cycle-dependent oscillation was confirmed by three independent approaches, demonstrating that even upon rearrangement, the expression of cyclin D1 is regulated in a cyclical manner. Antibody-mediated and anti-sense oligonucleotide 'knockout' experiments revealed that the aberrantly expressed BCL-1/cyclin D1 protein is required for G1 phase progression of all four B-cell tumours with the BCL-1 rearrangement. Consistent with the proposed oncogenic role of this cyclin, our data demonstrate that the BCL-1 deregulation caused by chromosomal rearrangement leads to expression of a functionally active cyclin D1 protein which subverts the G1 phase control in the human B-cell tumours carrying the t(11;14) translocation.

Base Sequence↗
PubMed1993

mb-1: a new marker for B-lineage lymphoblastic leukemia.

The expression of the Ig-linked mb-1 polypeptide was analyzed by immunocytochemistry (alkaline phosphatase anti-alkaline phosphatase technique) using a specific monoclonal antibody in 165 cases of acute leukemia, with 88 being lymphoblastic (ALL) and 77 myeloid (AML). The purpose of the study was to investigate the specificity of this reagent for B-lineage cases and its reactivity on leukemias that coexpress myeloid and B-cell antigens (biphenotypic). The majority (89%) of 72 B-cell precursor ALL patients were positive. Of these, mb-1 was expressed in all 9 patients with early-B-ALL (CD10-, c mu-), in all 11 patients with pre-B-ALL (c mu+) and in the single case of B-ALL (smIgM+). Forty-three of 51 patients with common-ALL (CD10+, c mu+) were also positive. All 16 T-lineage ALL patients and 72 (93.5%) of the AML patients examined were mb-1 negative. Four of the 5 mb-1-positive AML patients were considered biphenotypic and expressed other B-cell antigens such as CD10, CD19, and/or cCD22 and all showed rearrangement of the Ig heavy chain genes. Within the AML cases, mb-1 and cCD22 were more useful than other B-cell antigens in detecting biphenotypic cases, and mb-1 showed the highest correlation with the clonal rearrangement of Ig heavy chain genes. These results indicate that mb-1 is a sensitive and specific reagent for B-lineage blasts that will aid in the classification of B-cell precursor ALL and in the identification of biphenotypic leukemia presenting as AML.

Antibodies, Monoclonal↗
PubMed1993

Unusual deletions within the immunoglobulin heavy-chain locus in acute leukemias.

We have investigated the structure of the Ig heavy (IGH) chain locus in 309 cases of acute leukemia. Seventy-one cases of B-cell precursor (BCP) acute lymphoblastic leukemia (ALL) were analyzed: in six cases deletion of joining (JH) segments in the presence of cytogenetically normal chromosome 14 was observed. Similar deletions were seen in 1 out of 8 cases of biphenotypic acute leukemia analyzed: this case exhibited t(9:22)(q34;q11) and coexpressed both myeloid and B cell differentiation antigens. Five of the 7 cases analyzed had deleted the JH segments from both chromosomes. Because these deletions may have contributed to the pathogenesis of the disease we have attempted to define their boundaries. Using probes that map both 5' and 3' of JH, the 3' (centromeric) boundary of the deletions was mapped to an approximately 30-kb central region of the 60 kb between C delta and C gamma 3 in 10 of the 12 deleted chromosomes. In the remaining two chromosomes, the 3' boundary mapped to S mu. The 5' (telomeric) boundary could not be defined. However, three cases with biallelic deletion of JH showed biallelic deletion of the most proximal variable (VH) (VH6 and VH5-B2) genes, indicating that the deletions spanned over 500 kb. VH5-B1 and VH5-B3 were retained in germline configuration and no gross deletions were observed using a VH3 subgroup-specific probe, indicating that the 5' boundary mapped within the VH locus. Unusual deletions of the portion of the IgH locus including JH segments and the C mu and C delta genes may occur in acute leukemias with immunophenotypic evidence of commitment to the B cell differentiation pathway. The possible consequences of the deletions remain to be determined. However, the clustering of the centromeric boundary of the deletions to S mu and to a region between the C delta-C gamma 3 genes, a known "hot spot" for recombination, may indicate the operation of a distinct pathogenic mechanism.

Acute Disease↗
PubMed1993

C-MYC translocations in de novo B-cell lineage acute leukemias with t(14;18)(cell lines Karpas 231 and 353).

Rare de novo acute leukemias of mature B cells may exhibit the chromosomal translocation t(14;18)(q32.3; q21.3). We report the preliminary characterization of two cases that exhibited not only t(14;18)(q32.3;q21.3) but also the novel translocation t(8;9)(q24.1;p13.3), involving the C-MYC locus with unknown sequences at 9p13.3. From these cases, two Epstein-Barr virus negative cell lines (Karpas 231 and 353) with features identical to those seen in fresh cells from the patient have been derived. Both cell lines have complex karyotypes: in addition to both t(14;18)(q32.3;q21.3) and t(8;9)(q24.1;p13.3), cell line Karpas 231 exhibited three-way translocation t(1;3;11) (q42.3;q27.1;q23.1), whereas Karpas 353 exhibited t(1;3;7)(p32.1;q21.1;q22.1). Both cases retained immunophenotypes characteristic of mature B cells with no evidence for commitment to other hematopoietic lineages. Both cases expressed abundant, normal-sized C-MYC transcript, but no rearrangement of C-MYC DNA sequences could be detected using probes that span 80 kb around the C-MYC coding sequences. Breakpoints within the BCL-2 gene were divergent. In Karpas 353 the BCL-2 breakpoint occurred within the 3' untranslated major breakpoint region (mbr) of the gene, whereas, in Karpas 231, breaks in both the 3' mbr and in the region 5' of the gene were detected. The cytogenetic combination of t(14;18)(q32.3;q21.3) and t(8;9)(q24.1;p13.3) has been previously reported in diffuse B cell lymphomas. This combination may be a new recurrent abnormality, of central pathogenic importance in the transformation of B cells to high grade malignancies through simultaneous deregulation of BCL-2 and C-MYC genes, constitutive expression of C-MYC being driven by currently unknown DNA sequences on chromosome 9p13.3. The presence of other complex translocations including those affecting 11q23.1 may further accelerate the process of acute transformation.

Acute Disease↗
PubMed1993

The chromosomal translocation t(X;14)(q28;q11) in T-cell pro-lymphocytic leukaemia breaks within one gene and activates another.

Chromosomal translocation t(X;14)(q28;q11) has been observed in patients with pro-lymphocytic T-cell leukaemia (T-PLL). In two cases of T-PLL, one of which was associated with Ataxia telangiectasia (AT), the chromosomal break occurred in two different introns of a gene c6.1A, located at the Xq28 locus. Fusion transcripts, consisting of 5' sequences of c6.1A and the TCR alpha constant (C) region, were expressed at high levels in the leukaemic cells from both patients, but in only one case did this fusion generate an in-frame c6.1A-C alpha mRNA. However, the breaks within c6.1A seem to affect another gene, c6.1B, which is transcribed from the same CpG rich island as c6.1A but in the opposite transcriptional orientation. The c6.1B gene is not damaged by the translocation but is transcribed in both T-PLL cases. Furthermore, c6.1B may lack protein coding capacity and thus this translocation might result in a novel mechanism in tumorigenesis. In any event, this is the first cloned gene which is implicated in pathogenesis of chronic/pro-lymphocytic leukaemia of the T-cell lineage.

Aged↗
PubMed1993

A new human T-cell lymphoma cell line (Karpas 384) of the T-cell receptor gamma/delta lineage with translocation t(7:14) (p13;q11.2).

A new human T-cell non-Hodgkin lymphoma cell line of the T-cell receptor (TCR) gamma/delta lineage has been derived from the peripheral blood of a patient with a subcutaneous T-cell lymphoma in leukemic phase. The cell line (Karpas 384) initially had the same characteristics as malignant cells from the patient. Both the original tumor and the cell line failed to express any T-cell differentiation antigens other than very weak cell-surface expression of CD3 and cytoplasmic CD7; with continued growth in vitro, surface CD3 became undetectable in the presence of maintained strong cytoplasmic expression. The cell line has a complex karyotype with six abnormal chromosomes exhibiting not only t(7;14) (p13;q11.2) but also inv7(p13;q22.1), t(1;2)(q11;q35), t(2;1;14) (q35;q11-q32.1;q22.1), interstitial deletion 12(q24.1q24.3), and an unidentified marker chromosome. DNA blot analysis showed that TCR C beta and TCR J alpha-C alpha DNA sequences were in germline configuration in all restriction endonuclease digests. TCR gamma sequences showed biallelic V gamma 9-J gamma P-C gamma 1 rearrangements, the TCR gamma rearrangement detected in the majority of normal TCR gamma/delta bearing cells. Use of a range of TCR delta probes showed biallelic deletion of both J delta 1 and J delta 2, but three rearranged fragments when probed with a 3' C delta genomic probe. Similar breakpoints at 7p13 have been reported in a wide range of hematologic malignancies. Molecular cloning of the t(7;14)(p13;q11.2) translocation breakpoint in this cell line may define new DNA sequences of oncogenic potential at the 7p13 locus.

Chromosome Aberrations↗
PubMed1993

Lineage commitment in biphenotypic acute leukemia.

Acute leukemias (ALs) with phenotypic and genotypic features of several hematopoietic lineages are difficult to classify and may represent the transformation of multipotent stem cells. We have studied immunological features of 200 cases of acute leukemia (109 acute myelogenous leukemia, AML, and 91 acute lymphoblastic leukemia, ALL, according to FAB criteria), including 17 (8.5%) classified as biphenotypic by a scoring system based on the number and specificity of unexpected lineage antigens and which gives more weight to cytoplasmic markers such as myeloperoxidase, CD3, and CD22, and less to other membrane markers. Sixty-eight AML and 42 ALL cases were also examined for rearrangements of the immunoglobulin (Ig) and T-cell receptor (TCR) beta, gamma, and delta genes, and these included 12 biphenotypic AL. The expression of myeloid antigens in ALL was seen in 25% of the cases. All B-lineage ALL had rearrangements and/or deletions of the Ig genes whereas TCR beta, gamma, and delta genes were rearranged in 21%, 52%, and 71%, respectively. TCR delta, gamma and/or beta were rearranged in T-ALL and four out of 13 cases had Ig gene rearrangement. Lymphoid-associated antigens were expressed in 40% of AML cases; those most frequent expressed were CD7 (17%), CD2 (15%), CD19 (10%), and CD10 (7.5%). Evidence of Ig and/or TCR gene rearrangements was detected in 12% of AML cases. There was no correlation between the isolated expression of terminal deoxynucleotidyl transferase (TdT), B, and T-cell antigens with Ig and TCR gene rearrangements. However, in cases of AML defined as biphenotypic because they expressed two or more lymphoid antigens there was a statistically significant correlation between gene rearrangements and lymphoid score (p < 0.001). Our findings support the concept of biphenotypic leukemia as a distinct entity in which there is frequent correspondence between phenotypic and genotypic changes.

Acute Disease↗
PubMed1992

Ultrastructural localization of bcl-2 protein.

Previous cell subfractionation studies have indicated that bcl-2 is an inner mitochondrial membrane protein. We have sought to determine the ultrastructural localization of bcl-2 protein in lymphoma and breast carcinoma cell lines and biopsy material known to overexpress bcl-2 using immunoelectron microscopy. To avoid the possibility of processing artifacts, samples were prepared by three different methods: progressive lowering of temperature, cryosectioning, and freeze-substitution. In all instances the labeling of bcl-2 protein was relatively weak but the distribution the same. In both lymphoma and breast carcinoma tissues, bcl-2 protein was detected on the periphery of mitochondria: little labeling of either the mitochondrial matrix or cristae could be detected. Labeling was also detected on the perinuclear membrane and throughout the cytoplasm, as also indicated by confocal microscopy. These data therefore indicate that bcl-2 protein can be detected at several intracellular sites and that at the likely functional destination, the mitochondria, there appears to be, contrary to expectations, a preferential association with the outer membrane.

Breast Neoplasms↗
PubMed1990

A new human B-cell non-Hodgkin's lymphoma cell line (Karpas 422) exhibiting both t (14;18) and t(4;11) chromosomal translocations.

A unique B-cell non-Hodgkin's lymphoma (NHL) cell line (Karpas 422), bearing both t(14;18) and t(4;11) chromosomal translocations as well as several other chromosomal abnormalities, has been established from the pleural effusion of a patient with chemotherapy-resistant NHL. This cell line has the same karyotypic features as malignant cells from the patient. The major cell clone is characterized chromosomally by 46,XX t(2;10)(p23;q22.1), t(4;11)(q21.3; q23.1), t(14;18)(q32.1;q21.3), t(4;16)(q21.3;p13.1). Both phenotypically and genotypically, the cell line has features of a mature B-cell neoplasm with no evidence for commitment to other lineages. Rearrangements of the C-ETS-1 oncogene and N-CAM-1 and CD3 genes that map to 11q23 were not detected by conventional Southern analysis. BCL-2 was rearranged within the major breakpoint cluster. The K422 cell line has a unique karyotype; this is the first occasion that the t(4;11) translocation has been described in a t(14;18) lymphoma. The cell line will be of value in determining the molecular nature of the t(4;11) translocation.

Antigens, CD↗
PubMed1989

T-cell receptor delta/alpha rearrangements in lymphoid neoplasms.

Rearrangements within the T-cell receptor (TCR)delta/alpha locus were analyzed in a wide variety of lymphoid neoplasms by eight DNA probes specific for TCR J delta, J alpha and C alpha segments. In all 11 T-cell malignancies, rearrangement and/or deletion of TCR delta was detected irrespective of the stage of maturation of the tumor. The organization of TCR delta correlated with the phenotype of the tumor: In "prethymic" T-cell acute lymphocytic leukemia (ALL), TCR delta was the only TCR gene to be rearranged. More mature T cell malignancies expressing CD4 together with CD3 showed deletion of both alleles of TCR delta, suggestive of TCR V alpha-J alpha rearrangement. All 43 B-cell tumors expressing surface immunoglobulin (sIg), including two cases of adult B-cell ALL, had germline configuration of TCR delta/alpha. In contrast, all 17 B-cell precursor ALLs (null, common, and pre-B-cell ALLs) had rearrangement and/or deletion of TCR delta/alpha. A single case of "histiocytic" lymphoma also showed biallelic deletion of TCR delta. Oligoclonal rearrangements of Ig and TCR genes were observed in two cases of B-cell precursor ALL and in one case of T-cell lymphoblastic lymphoma. Patterns of such "aberrant" TCR rearrangement were similar to those observed in T-lineage malignancies. In particular, seven of eight cases of B-cell precursor ALL and the histiocytic lymphoma which demonstrated biallelic TCR delta deletion, (suggestive of a V alpha-J alpha rearrangement) had clonal TCR beta rearrangement. These data support the hypothesis that supposedly aberrant rearrangements of the TCR genes may follow the same developmental controls as found in T-cell differentiation, despite the lack of evidence for further commitment to the T-cell lineage. TCR delta rearrangement is a useful marker of clonality of immature T-cell tumors which may have only this gene rearranged but is not specific to the T-cell lineage.

Adult↗
PubMed1989

Effects of CAMPATH-1 antibodies in vivo in patients with lymphoid malignancies: influence of antibody isotype.

The CAMPATH-1 family of antibodies recognize an abundant glycoprotein expressed on virtually all human lymphocytes. All rat IgM and IgG antibodies of this specificity are lytic with human complement, but only IgG2b is active in antibody-dependent cell-mediated cytotoxicity (ADCC). We compared the ability of IgM, IgG2a, and IgG2b to deplete lymphocytes in vivo in two patients with prolymphocytic transformation of B-cell chronic lymphocytic leukemia (CLL). The IgM (CAMPATH-1M) produced transient depletion of blood lymphocytes with consumption of complement but had no effect on solid masses or bone marrow. Similar transient depletion of blood lymphocytes was noted with the IgG2a (YTH34.5). In contrast, the IgG2b (CAMPATH-1G) produced long-lasting depletion of lymphocytes from blood and marrow and improvement in splenomegaly but no detectable changes in complement levels. These differences probably reflect the importance of Fc receptor binding for effective clearance of target cells in vivo. We treated 16 more patients with a variety of lymphoid malignancies and noted consistent effects on blood lymphocytes, marrow infiltration, and splenomegaly. At this dose level, there was comparatively little improvement in affected lymph nodes or extranodal masses. Nevertheless, the in vivo lympholytic ability of CAMPATH-1G is very potent as compared with other monoclonal antibodies (MoAbs) and may have applications in therapy of lymphoid malignancies and as an immunosuppressive agent.

Aged↗