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D Y Mason

Publications and source records attributed to D Y Mason.

At least 91 records · Page 5Linked to original sources
PubMed1993

Heterogeneity of CD3 antigen expression in T-cell lymphoma.

CD3 antigen expression was studied in a series of 98 T-cell lymphomas, using polyclonal antibodies which recognize this molecule in routinely processed, paraffin-embedded, tissue. We identified 40 cases in which CD3 was present on only a proportion of the neoplastic cells. This phenomenon of heterogeneous CD3 expression was commonest in pleomorphic T-cell lymphomas (22/42 cases) and in CD30 (Ki-1)-positive lymphomas (5/11 cases), and was less frequently observed in mycosis fungoides (4/18 cases) and not seen in T-cell lymphoblastic lymphoma (0/9 cases). CD3 expression was often related to cell morphology, with CD3 antigen being present on the smaller neoplastic cells but absent from the larger ones. The diagnostic significance of these observations is that, on occasion, it may be possible to diagnose a lymphoma as being of T-cell origin in paraffin sections by demonstrating a minor subpopulation of CD3-positive neoplastic cells.

CD3 Complex↗
PubMed1993

CD68 reactivity of non-macrophage derived tumours in cytological specimens.

AIMS: To investigate the presence of the macrophage associated antigen CD68 in non-haematopoietic tumours. METHODS: Cytological specimens from non-macrophage derived tumours were stained using the alkaline phosphatase anti-alkaline phosphatase immunocytochemical method (APAAP) and three monoclonal anti-CD68 antibodies, Y1/82A, EBM11, and KP1. RESULTS: Reactivity of malignant cells with one or more of the antibodies was seen in 11 out of 40 adenocarcinomas and in one of seven poorly differentiated carcinomas; other neoplasms, including 10 cases of squamous carcinoma, three of malignant melanoma, and four of oat cell carcinoma were negative. Monoclonal antibody KP1 gave the strongest staining and reacted with the highest proportion of neoplastic cells. CONCLUSIONS: CD68 is expressed in a proportion of epithelial tumours although the labelling is usually less intense than in macrophages. Anti-CD68 antibodies should therefore be used as part of a panel in the diagnosis of poorly differentiated neoplasms in cytological material.

Adenocarcinoma↗
PubMed1993

Transcription and protein expression of mb-1 and B29 genes in human hematopoietic malignancies and cell lines.

The transmembrane forms of all immunoglobulin (Ig) classes are associated with two glycoproteins, mb-1 and B29, that are crucial for signal transduction following antigen binding to the Ig molecule. We have investigated the transcription and protein expression of mb-1 and B29 genes during B-cell development. Sixty human continuous cell lines (35 B-lineage, 11 T-lineage, 11 myeloid-lineage and three non-hematopoietic) and 75 hematopoietic malignancies (55 B-lineage, 12 T-lineage and eight myeloid-lineage), were tested for RNA expression by Northern blotting experiments with the mb-1 pRA3 cDNA probe, and a newly isolated B29 cDNA probe. Protein expression was analyzed by immunofluorescence microscopy of cytocentrifuge preparations, which were labeled with the anti-mb-1 HM57 monoclonal antibody (mAb) and an anti-B29 polyclonal antiserum, directed against intracellular epitopes of these polypeptides. Except for two early precursor B-cell lines, mb-1 and B29 transcripts and proteins were detected in all B-cell lines and B-cell malignancies, i.e. from immature to more mature B cells, irrespective of their Ig class expression. Transcription of mb-1 genes seems to be down-regulated at the plasma cell stage, because no mb-1 transcripts and mb-1 proteins could be detected in the four plasma cell lines and two plasma cell leukemias tested. B29 transcripts were detectable in these cell samples, but low levels of B29 proteins were only detected in one plasma cell line. The HM57 mAb gave strong labeling on fresh cytocentrifuge preparations of all B-cell samples, and this mb-1 protein expression appeared to be B-cell specific. We therefore conclude that the HM57 mAb is well suited for the detection of the mb-1 molecule as a pan-B-cell marker for the diagnosis of immature and mature B-cell malignancies. The expression pattern of the mb-1 protein is comparable to that of the CD19 and CD22 antigens, but has the advantage of being B-lineage specific. Although B29 protein expression was restricted to B-lineage cells, the anti-B29 antiserum is less suitable for diagnosis of B-cell malignancies, because of the variable and generally weak signals on cytocentrifuge preparations.

Antigens, CD↗
PubMed1992

Molecular cloning of ICAM-3, a third ligand for LFA-1, constitutively expressed on resting leukocytes.

The co-ordinated function of effector and accessory cells in the immune system is assisted by adhesion molecules on the cell surface that stabilize interactions between different cell types. Leukocyte function-associated antigen 1 (LFA-1) is expressed on the surface of all white blood cells and is a receptor for intercellular adhesion molecules (ICAM) 1 and 2 (ref. 3) which are members of the immunoglobulin superfamily. The interaction of LFA-1 with ICAMs 1 and 2 provides essential accessory adhesion signals in many immune interactions, including those between T and B lymphocytes and cytotoxic T cells and their targets. In addition, both ICAMs are expressed at low levels on resting vascular endothelium; ICAM-1 is strongly upregulated by cytokine stimulation and plays a key role in the arrest of leukocytes in blood vessels at sites of inflammation and injury. Recent work has indicated that resting leukocytes express a third ligand, ICAM-3, for LFA-1 (refs 11, 12). ICAM-3 is potentially the most important ligand for LFA-1 in the initiation of the immune response because the expression of ICAM-1 on resting leukocytes is low. We report the expression cloning of a complementary DNA, pICAM-3, encoding a protein constitutively expressed on all leukocytes, which binds LFA-1. ICAM-3 is closely related to ICAM-1, consists of five immunoglobulin domains, and binds LFA-1 through its two N-terminal domains.

Amino Acid Sequence↗
PubMed1992

Immunoglobulin M and D antigen receptors are both capable of mediating B lymphocyte activation, deletion, or anergy after interaction with specific antigen.

A series of immunoglobulin (Ig)-transgenic mice were generated to study the functional capabilities of the IgM and IgD classes of B lymphocyte antigen receptor in regulating both cellular development and responses to specific antigen. B cells from Ig-transgenic mice expressing either hen-egg lysozyme (HEL)-specific IgM or IgD alone were compared with B cells from mice that coexpressed IgM and IgD of the same anti-HEL specificity. In all three types of Ig-transgenic mice, conventional B cells specific for HEL exhibited exclusion of endogenous Ig expression and matured to populate the usual microenvironments in peripheral lymphoid tissues. These peripheral B cells could be stimulated by HEL through either IgM or IgD antigen receptors to generate T cell dependent antibody production in vivo or to enhance T cell independent proliferative responses to lipopolysaccharide in vitro. Conversely, when HEL was encountered in vivo as a self-antigen, B cells expressing HEL-specific IgM or IgD alone were both rendered tolerant. In each case this occurred by clonal anergy in response to soluble autologous HEL, and clonal deletion when HEL was recognized as a membrane-bound self-antigen. Taken together, these findings indicate that IgM and IgD antigen receptors expressed alone on conventional B cells can support normal differentiation, antigen-dependent activation, and induction of self-tolerance, the only overt difference lying in a greater degree of receptor downregulation for IgM relative to IgD after induction of clonal anergy by soluble HEL.

Animals↗
PubMed1992

Comparison of human B cell antigen receptor complexes: membrane-expressed forms of immunoglobulin (Ig)M, IgD, and IgG are associated with structurally related heterodimers.

We have recently reported that on human B lymphocytes, membrane IgM (mIgM) associates with a heterodimer of 47- and 37-kD polypeptides, the 47-kD subunit being encoded by the mb-1 gene. We show here that expression of mb-1, both at the mRNA and the protein level, is not restricted to IgM+ B cells but can also be found in IgM- pre-B cells and mIgM-IgG+ B cells. Membrane forms of IgD and IgG, isolated from freshly isolated human B cells and B cell lines, are expressed together with heterodimeric protein structures biochemically similar to the mIgM-associated polypeptides, and these were shown to comprise the products of the mb-1 and B29 genes, or homologous genes. Finally, all three classes of antigen receptors are linked to protein kinases, capable of phosphorylating the Ig-associated heterodimers. Our findings provide insight in the structural organization of the different antigen receptors on human B cells and have implications for their function.

Antibodies, Monoclonal↗
PubMed1992

The B29 and mb-1 polypeptides are differentially expressed during human B cell differentiation.

Surface immunoglobulin on mouse B cells is associated with a heterodimer comprising the products of the mb-1 and B29 genes. Here we report that antibodies raised against a peptide sequence from the intracytoplasmic C terminus of the B29 murine gene product detect the 37-kDa component of the human heterodimer, indicating that this component in man is also encoded by the B29 gene. The immunocytochemical reactivity of these anti-B29 antibodies was compared with those of antibodies to the mb-1 protein. Of 25 cases of acute lymphoblastic leukaemia (ALL), 24 were positive for mb-1 whereas B29 was expressed in only 13 cases. Most of these B29-positive ALL expressed immunoglobulin mu heavy chain in their cytoplasm (pre-B ALL). In lymphoid tissue sections, anti-B29-labeled B cell follicles in a similar fashion to anti-mb-1, with the striking exception that plasma cells were unreactive for B29, but positive for mb-1. These results suggest that the synthesis of B29 begins later in precursor B cells than that of mb-1, and ceases before the terminal plasmacyte phase.

Animals↗
PubMed1992

Evaluation of bcl-2 protein expression and 14;18 translocation as prognostic markers in follicular lymphoma.

Conflicting results have been published on the prognostic significance of t(14;18) in follicular lymphoma: Yunis et al. (1989) reported that its presence indicated poor response to therapy and short survival, whereas Levine et al. (1988) showed no difference in prognosis between cases with and without the translocation. However these results were based on small series of cases and on follow-up periods (no longer than 7 years) which are relatively short for a disease with such a slow clinical evolution. Here we report an investigation of 70 cases of follicular lymphoma with long term follow-up data (up to 17 years). This series has been studied for the presence of the 14;18 translocation and for the expression of bcl-2 protein. Our results show that there are no grounds for considering either the 14;18 translocation or the expression of the bcl-2 protein to be useful prognostic markers in clinical practice.

Blotting, Southern↗
PubMed1992

Development and follicular localization of tolerant B lymphocytes in lysozyme/anti-lysozyme IgM/IgD transgenic mice.

To analyse mechanisms of immunological self-tolerance, a detailed comparison of the development and fate of lysozyme-specific B lymphocytes was carried out in transgenic mice expressing rearranged anti-lysozyme IgM/IgD Ig transgenes in the absence or presence of an additional transgene encoding lysozyme itself. In the absence of lysozyme, B cell development, localization, and differential expression of transgene-encoded IgM and IgD occurred in the normal sequence in Ig transgenic mice, establishing that these animals provide a physiological model for studies of B cell selection in vivo. By contrast, in lysozyme-expressing double-transgenic mice, tolerant lysozyme-reactive B cells persisted within the follicular mantle zones in the spleen, lymph nodes, and Peyer's patches, but were eliminated from the splenic marginal zones. It could be shown that lysozyme-binding and induction of tolerance occurred as soon as surface Ig was expressed on immature B cells in the bone marrow of the double-transgenic mice although this did not prevent maturation, emigration from the bone marrow, and localization in peripheral lymphoid follicles. These findings, together with recent examples of aborted maturation of self-reactive B cells, indicate two functionally distinct antigen receptor signalling events in immature B cells and suggest a unique role for the follicular microenvironment.

Animals↗
PubMed1992

Monoclonal antibody JC1: new reagent for studying cell proliferation.

AIM: To characterise a newly developed mouse monoclonal antibody JC1 which recognises a nuclear antigen present in proliferating cells in normal tissues and neoplastic lesions, and which is absent in resting cells. METHODS: The methodology was established using a representative range of frozen sections from normal tissues and from certain tumours which were immunostained with antibodies Ki67 and JC1. The molecular weight of the antigen recognised by JC1 was obtained by western blot analysis and this was compared with that of Ki67. IM-9 cell lysates containing Ki67 derived plasmids were also tested with JC1 antibody. RESULTS: Biochemical investigation indicated that the antigen recognised by JC1 gives two molecular weight bands of 212 and 123 kilodaltons, which is distinct from the well characterised anti-proliferation monoclonal antibody Ki67 (395-345 kilodaltons). In addition recombinant Ki67 protein is not recognised by JC1. Immunohistological reactivity was seen in areas known to contain numerous proliferating cells such as lymphoid germinal centres, splenic white matter, cortical thymocytes and undifferentiated spermatogonia. In tumours many cells from adenocarcinomas, oat cell carcinomas, squamous cell carcinomas of lung, and seminomas were labelled by JC1 with a distribution and proportion similar to that seen with Ki67. In normal tissues the only apparent difference was in testis where JC1 stained a considerably greater number of cells than Ki67. In all cases studied the new antibody showed nuclear reactivity only. JC1 did not show any cytoplasmic crossreactivity with squamous cells as is frequently seen with Ki67. CONCLUSION: Antibody JC1, which recognises a nuclear antigen present in proliferating cells, should provide a useful adjunct to Ki67 as a marker of proliferation especially in those cases such as squamous cell carcinomas where a Ki67 index cannot be determined.

Animals↗
PubMed1992

Immunohistological detection of human cytotoxic/suppressor T cells using antibodies to a CD8 peptide sequence.

AIMS: To evaluate whether cytotoxic/suppressor T cells can be detected in paraffin wax embedded human tissue samples using antibodies to a synthetic CD8 peptide sequence. METHODS: Polyclonal and monoclonal antibodies were raised against a 13 amino acid peptide sequence from the cytoplasmic portion of the alpha chain of the human CD8 molecule. RESULTS: These antibodies specifically detected the native form of the CD8 polypeptide when tested by immunoprecipitation with radiolabelled T cells, and gave the expected staining pattern for cytotoxic/suppressor T cells in cryostat sections. Being raised in rabbits, the polyclonal antibodies were also useful for double labelling for CD8 in conjunction with monoclonal antibodies. CD8 positive cells could also be detected in paraffin wax embedded tissues. This was achieved without prior treatment of the sections if the tissue had been fixed in Bouin's fixative. When tissues had been exposed to conventional formalin fixation, preliminary microwave treatment was required. CONCLUSIONS: These findings provide further evidence that antibodies against leucocyte associated antigens, capable of reacting on paraffin wax embedded tissue, can be produced by immunisation with synthetic peptide sequences.

Amino Acid Sequence↗
PubMed1992

Heterogeneity of vascular endothelial cells with relevance to diagnosis of vascular tumours.

AIMS: To determine the distribution of factor VIII related antigen, CD31, CD34 and CD36 in normal and malignant human vascular tissues using a panel of well characterised monoclonal antibodies. METHODS: Frozen and fixed material from a wide range of normal tissues and routinely processed material from 43 benign and malignant vascular tumours were examined. Single immunocytochemical labelling was performed using the APAAP technique. Double staining involved the sequential use of APAAP with the peroxidase method. RESULTS: Human vascular endothelium was antigenically heterogeneous. One of the most restricted markers was factor VIII related antigen, despite its having been widely used in diagnostic pathology as a marker of vascular endothelium and of the tumours which arise from it. Three antibodies against factor VIII related antigen, CD31 (JC70) and CD34 (QBend 10) were identified as immunostaining routinely processed, formalin fixed, paraffin wax sections. Each antibody gave different staining when tested on a range of vascular tumours, both benign and malignant. CONCLUSIONS: A small panel of three reagents (factor VIII related antigen, CD31 (JC70) and CD34 (QBend 10)) should be used by diagnostic pathologists who want to show the presence of cells of endothelial origin in routine material.

Antigens, CD↗
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↗
PubMed1992

Expression of the bcl-2 gene product in follicular lymphoma.

Expression of bcl-2 protein was analyzed in 140 cases of follicular lymphoma by immunohistologic staining of paraffin-embedded tissue; 85% of cases were positive, the frequency being related to histologic grade (100% for the small-cleaved cell type, 86% for the mixed cell type, and 76% for the large cell group). There was striking heterogeneity of bcl-2 content in a number of cases and the smaller neoplastic cells (i.e., centrocytes) were usually the most strongly labeled. In most cases, bcl-2 protein staining was much weaker in normal lymphoid cells than in the neoplastic cells. In several cases, staining for bcl-2 revealed patterns of neoplastic cell spread into adjacent tissue (e.g., normal follicles, lymphoid sinuses), and bcl-2 protein expression tended to be highest in these migratory cells.

Humans↗