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D Y Mason

Publications and source records attributed to D Y Mason.

At least 109 records · Page 6Linked to original sources
PubMed1992

Relative expression of surface IgM, IgD and the Ig-associating alpha(mb-1) and beta(B-29) polypeptide chains.

Membrane immunoglobulins are associated with a transmembrane disulphide-linked heterodimer composed of an alpha-chain (mb-1) and a beta-chain (B-29). The relative surface expression of all of the polypeptide chains comprising the Ig-alpha beta complex has been investigated using surface labelling coprecipitation analysis and two-colour flow cytometric analysis. The main conclusions are that mb-1 and B-29 are B-cell surface markers on immature and mature B cells, and that all components of the surface Ig-alpha beta complex are expressed in stoichiometrically equivalent amounts. Thus the complex was quantitatively precipitated from digitonin lysates of 125I-surface-labelled cells with anti-B-29, anti-mb-1 or anti-Ig. Secondly, by two-colour FACS analysis there was a proportionality between the relative amounts of cell surface mb-1 or B-29 and surface IgM or IgD, but not other B-cell markers (class II, B220, FcR gamma, FcR epsilon). Finally there was an insignificant number of B cells expressing membrane Ig without alpha- and beta-chains, and vice versa. Thus there appears to be a closely controlled relative synthesis and surface expression of all components of the B-cell receptor complex.

Animals↗
PubMed1992

A monocyte/macrophage antigen recognized by the four antibodies GHI/61, Ber-MAC3, Ki-M8 and SM4.

A new monoclonal antibody, GHI/61, which labels the majority of monocytes and tissue macrophages is described. This antibody recognizes an intracellular antigen of 130,000 MW (reduced) and 110,000 MW (unreduced). Using biochemical, flow cytometry and immunocytochemical studies antibody GHI/61 was shown to recognize the same antigen as the previously described antibodies Ber-MAC3, Ki-M8 and SM4. On the basis of the results obtained, antibodies GHI/61, SM4, Ber-MAC3 and Ki-M8 should form a new CD group at the next Leucocyte Typing Workshop. Since the antigen recognized by the antibody GHI/61 is relatively easy to purify, the sequencing and the isolation of the gene encoding this protein should be possible.

Antibodies, Monoclonal↗
PubMed1991

The IgM-associated protein mb-1 as a marker of normal and neoplastic B cells.

Recent evidence indicates that the transmembrane form of IgM on murine and human B lymphocytes is physically associated with at least two proteins, forming a disulfide-linked dimer, which may control cell surface expression of IgM and also play a role in signal transduction after Ag binding (by analogy with the TCR-associated CD3 components in T lymphocytes). We have used mAb and polyclonal antibodies against an intracytoplasmic epitope on one of these polypeptides (previously identified in murine B cells as the product of the B cell specific mb-1 gene) to study the distribution of the IgM-associated dimer in human cells. By immunocytochemical staining of normal and neoplastic B cells, we show that the human mb-1 protein appears early in B cell differentiation, probably before expression of cytoplasmic mu-chain, and persists until the plasma cell stage, where it is seen as an intracytoplasmic component. According to immunohistologic analysis of reactive lymphoid tissue and lymphoma samples, mb-1 protein is completely B cell specific. Anti-mb-1 also labels B cell areas in tissues from seven different mammalian species. Finally, the Ig-associated dimer could be isolated from human hairy-cell leukemia cells in high purity and yield by affinity chromatography using anti-mb-1 antibody. Mice immunized with this material have produced a strong polyclonal response, so that it should now be possible to prepare a panel of new mAb reactive with different epitopes on both mb-1 and on its associated polypeptide(s).

Animals↗
PubMed1991

The membrane IgM-associated heterodimer on human B cells is a newly defined B cell antigen that contains the protein product of the mb-1 gene.

7/8embrane IgM (mIgM) on human B lymphocytes is noncovalently associated with a disulfide-linked dimer that contains phosphoproteins of 47 and 37 kDa. In this study, the biochemical properties and the identity of these Ag receptor-associated components have been addressed. Both subunits carry N-linked carbohydrate groups. After deglycosylation, the 47-kDa and 37-kDa proteins have similar molecular masses, of about 23 kDa, and relatively acidic but different isoelectric points. The accumulated data, together with a previously performed comparison of tryptic peptides, suggest that the two components are structurally distinct and possibly encoded by different genes. Indeed, a mAb, raised against a synthetic peptide that was made on the basis of the published carboxyl-terminal amino acid sequence of the human mb-1 gene product, specifically reacted with the 47-kDa but not the 37-kDa subunit. None of the established B cell-specific mAb characterized in the Fourth International Workshop on Leukocyte Antigens, including CD24, CD37, and CD72, detect the mIgM-linked heterodimer, which makes it a newly defined human B cell Ag.

Antigens, CD↗
PubMed1991

Germinal center cells express bcl-2 protein after activation by signals which prevent their entry into apoptosis.

B cells undergo selection within germinal centers on the basis of their capacity to be activated by antigen held on follicular dendritic cells. Isolated germinal center B cells in culture kill themselves by apoptosis but this is prevented if their receptors for antigen are cross-linked. In this study it is confirmed that almost all germinal center B cells, unlike other B cells, do not express the 25-kDa protein encoded by the bcl-2 oncogene. Cross-linking the surface Ig of isolated germinal center cells causes them to express bcl-2 protein. Two other stimuli which inhibit the entry of germinal center cells to apoptosis result in the expression of bcl-2 protein. These stimuli are: (a) CD40 antibody and (b) recombinant 25-kDa fragment of the CD23 protein plus recombinant interleukin 1 alpha. Respectively, these induce germinal center cells to differentiate to resting B cells or plasmablasts. Dual-fluorescence studies on small lymphocytes confirm the presence of bcl-2 protein in mitochondria but show that this is also present in other extra-nuclear areas. Burkitt lymphoma cells have a phenotype which indicates that they are neoplastic cells of germinal center origin. The expression of bcl-2 protein by Burkitt lymphoma lines was also studied. Burkitt lines which retain the phenotype of fresh Burkitt lymphoma cells can be induced to enter apoptosis on culture with the Ca2+ ionophore ionomycin. These cells were found not to express bcl-2 protein. By contrast, Burkitt lines which have drifted towards a lymphoblastoid cell line phenotype and are resistant to the induction of apoptosis express high levels of the bcl-2 protein. The findings support the concept that the susceptibility of germinal center cells to entering apoptosis is associated with their lack of expression of bcl-2 protein. Aberrant expression of bcl-2 protein by some neoplastic germinal center cells may allow survival in situations where their normal counterparts die.

Antibodies, Monoclonal↗
PubMed1991

A 72-kD B cell-associated surface glycoprotein expressed at high levels in hairy cell leukaemia and plasma cell neoplasms.

The present paper describes two new MoAbs, GHI/75 and VMP55, which were raised against a glycoprotein enriched lysate of hairy cell leukaemia. These antibodies recognized a new antigen of 72 kD (unreduced) and 83 kD (reduced) molecular weight. GHI/75 and VMP55 gave very strong staining of plasma cells, moderate labelling of circulating B cells but only weak staining of monocytes, some tissue macrophages and lymphoid cells. Neither antibody reacted with neutrophils or any non-haematopoietic cells. Both antibodies, however, strongly labelled the tumour cells in hairy cell leukaemia, multiple myeloma, plasmacytoma and lymphoplasmacytic lymphomas. No staining was seen of the neoplastic cells in Hodgkin's disease, myeloid leukaemia or T cell lymphomas. The two antibodies, GHI/75 and VMP55, may be of value in the differential diagnosis of hairy cell leukaemias and plasma cell neoplasms. In addition, the ease with which their antigen can be purified provides the possibility for a detailed study of this molecule.

Antibodies, Monoclonal↗
PubMed1991

CD30 expression in follicular lymphoma.

The CD30 antigen is a characteristic phenotypic feature of Sternberg-Reed and Hodgkin cells and is also found in a subset of large cell non-Hodgkin's lymphomas. The finding of CD30 positive cells in some centroblastic/centrocytic (cb/cc) follicular lymphomas prompted us to characterize the presence and distribution of CD30 positive cells in this type of lymphoma, using the monoclonal antibody BerH2. CD30 positive cells were present in 17/19 of the cases studied, located mainly at the edge of the neoplastic follicles, but also in some cases in perinodular or T-cell areas. This distribution resembles that found in reactive tonsils and lymph nodes. The majority of these CD30 positive cells in cb/cc lymphoma seem to be B-cells, as suggested by their reactivity with B-cell markers demonstrated by double immunostaining. The nature of these CD30 positive cells is unclear, but they should be taken into consideration in the differential diagnosis of cb/cc lymphoma with lymphocyte predominance Hodgkin's disease.

Antibodies, Monoclonal↗
PubMed1991

Immunophenotyping of Nigerian cases of non-Hodgkin's lymphomas on paraffin sections.

One hundred cases of routinely fixed and processed non-Hodgkin's lymphoma from Nigeria were immunostained with a small panel of monoclonal antibodies against B-, T- and macrophage antigens. The aims of the study were to assess the suitability of stored material from a country like Nigeria for immunohistochemical examination and the ability of the antibody panel to evaluate the distribution of B- and T-cell neoplasms. Eighty-seven of the 100 cases gave interpretable immunostaining, with 75 being B-cell and 12 T-cell neoplasms. Eighty-seven of the 100 cases gave interpretable immunostaining, with 75 being B-cell and 12 T-cell neoplasms. There were no tumours of macrophage lineage. Four cases gave satisfactory staining of reactive lymphoid cells but no reactivity with malignant cells and thus were not phenotyped. The remaining nine cases gave no staining of neoplastic or reactive cells, suggesting that they were unsuitable for immunohistochemical study, presumably because of inappropriate fixation and handling. We concluded that a panel of three monoclonal antibodies is suitable for routine immunostaining of conventionally fixed and processed blocks in Third World countries and will give diagnostically useful information in approximately 95% of cases.

Antibodies, Monoclonal↗
PubMed1991

Ki-67 immunostaining and survival in operable lung cancer.

One hundred and eighty-seven operable lung tumours were immunostained with the monoclonal antibody Ki-67 and divided into groups of high, moderate or low proliferation. Patients have been followed clinically for up to 7 years to ascertain whether this immunocytochemical measurement reflected tumour behaviour in terms of survival. The majority of the tumours were squamous cell carcinomas (104 cases) and adenocarcinomas (60 cases). These were divided into three groups of low, intermediate and high growth fraction, in which survival was better for tumours of lower proliferative rate up to approximately 2 years after operation. By 5 years these differences had largely disappeared and all tumours of a particular type showed a similar survival curve. Small cell carcinomas (13 cases) had high Ki-67 labelling indices, with more than 60% of patients deal in the first year, whereas carcinoid tumours (10 cases) had low labelling rates and all but one are still alive. We conclude that measurement of lung tumour growth rate with the monoclonal antibody Ki-67 shows promise as a possible indicator of short-term survival and perhaps as a means of choosing a group of patients with adenocarcinomas and squamous cell carcinomas for post-operative chemotherapy.

Adenocarcinoma↗
PubMed1991

Immunohistological diagnosis of "plasmacytoid T cell lymphoma" in paraffin wax sections.

An immunohistological study of paraffin wax embedded tissue from three cases of plasmacytoid monocyte neoplasms, using a panel of antibodies which react with fixation resistant leucocyte markers, is reported. This neoplasm was found to have a distinctive antigenic profile, being negative for CD3 and elastase, but positive for CD43 and CD68. This immunological phenotype, coupled with its characteristic morphological features, should facilitate the recognition of this rare neoplasm in routinely processed tissue. Furthermore, the term "plasmacytoid monocyte sarcoma" is proposed to designate it because it is inappropriate to refer to it as a lymphoma. As all cases have been associated with a myeloproliferative disorder (usually an acute or chronic myeloid leukaemia), these tumours probably represent the accumulation in lymphoid tissue of neoplastic cells which have differentiated along the plasmacytoid monocyte pathway.

Aged↗
PubMed1991

Ber-ACT8: new monoclonal antibody to the mucosa lymphocyte antigen.

Using a newly established HTLV-1 positive T cell line as an immunogen, a new monoclonal antibody, Ber-ACT8, was produced. It reacts with in vitro activated T cells and a small subset of normal resting T cells, but not with resting B cells or any of the 29 established human permanent cell lines tested. Immunohistological analysis of a wide spectrum of human tissues showed that Ber-ACT8 reactivity is restricted to a few T cells in the peripheral blood, the extrafollicular areas of lymph nodes and tonsils, and splenic red pulp. In the gut Ber-ACT8 labelled most intraepithelial T cells and up to 50% of lamina propria T cells. The antibody also immunostained T cells present in the oral and bronchial mucosa. Double labelling on splenic cells, fresh blood lymphocytes, and in vitro activated T cells showed that most Ber-ACT8 positive cells coexpressed CD8. Ber-ACT8 did not react with any of the 14 Hodgkin's lymphomas nor any of the 172 non-Hodgkin's lymphomas tested, with the exception of 10 cases of T cell lymphomas, five of which were located in the jejunum and associated with coeliac disease, and one B cell lymphoma, and most cases of hairy cell leukaemia tested. Parallel immunostainings with Ber-ACT8, anti-TCR-beta (beta F1), and anti-TCR-delta showed that most Ber-ACT8 positive T cells carry the TCR of alpha beta type. Comparison of Ber-ACT8 with HML-1, B-ly7, and LF61 showed essentially the same reactivity and an identical molecular target. The molecular structure recognised seems to be a trimeric molecule with components of 150, 125 and 105 kilodaltons, with the Ber-ACT8 epitope localised on the 150 kilodalton chain. The 150 kilodalton molecule contains an 0-linked carbohydrate moiety of about 10 kilodaltons. Because of its very selective distribution, the trimeric antigen is a powerful reagent for the diagnosis of gut T cell-derived T cell lymphomas and other extranodal T cell lymphomas, as well as hairy cell leukaemia.

Animals↗
PubMed1991

Ultrastructural localization of the CD68 macrophage-associated antigen in human blood neutrophils and monocytes.

The ultrastructural localization of the CD68 antigen, a 110-kd intracellular glycoprotein associated with myeloid cells and with monocytes/macrophages, was investigated in human neutrophil granulocytes by postembedding immunogold staining, using monoclonal antibody KP1. The antigen was found in the primary granules of neutrophils, although not all primary granules were labeled. It was absent from the plasma membrane. In monocytes, it was also detected within cytoplasmic granules, colocalized with lysozyme and myeloperoxidase. This observation confirms and completes results obtained by immunofluorescence and other light-microscopic methods. Moreover this study shows that the CD68 epitope recognized by antibody KP1 is able to resist fixation and embedment and therefore emphasizes the value of using KP1 as a marker for this macrophage-associated molecule.

Antibodies, Monoclonal↗
PubMed1991

HML-1 antigen on mucosa-associated T cells, activated cells, and hairy leukemic cells is a new integrin containing the beta 7 subunit.

The monoclonal antibodies HML-1, B-ly7 and Ber-ACT8 recognize intramucosal gut T lymphocytes, activated cells, and hairy cell leukemia. The antigen on hairy cells consists of three glycoproteins (160 kappa D, 130 kappa D and 105 kappa D unreduced; 145 kappa D and 120 kappa D reduced). These peptides have biochemical features reminiscent of integrins but we have shown by immunoprecipitation that they are not known integrin subunits. We have used a newly produced antibody (BP6) to purify this molecule and shown by N-terminal sequence analysis that the smallest subunit is the product of integrin beta 7 cDNA. This molecule is thus a new member of the integrin family of leucocyte adhesion proteins. Immunoprecipitation experiments indicate that the two larger subunits are recognized by HML-1, B-ly7 and Ber-ACT8.

Amino Acid Sequence↗
PubMed1991

Alpha 1-antitrypsin is present within the primary granules of human polymorphonuclear leukocytes.

Elastase is a potent proteolytic enzyme found within human neutrophil primary granules. Its major inhibitor in the serum is alpha 1-antitrypsin, a protein that is synthesized by hepatocytes but which has recently also been shown to be synthesized by circulating neutrophils. The authors have therefore carried out an immunocytochemical study at the light microscopic and ultrastructural level to determine the intracellular localization of alpha 1-antitrypsin. Double labeling with colloidal gold showed that alpha 1-antitrypsin is localized at the same site as neutrophil elastase, i.e., within primary granules. Secondary granules (detected by labeling for lactoferrin) were unstained for alpha 1-antitrypsin. Elastase and its major inhibitor therefore coexist within the same granule population within human neutrophils. Some difference in their intraorganelle distribution existed at the ultrastructural level (in that elastase tended to be localized at the periphery of the granules whereas alpha 1-antitrypsin was usually diffusely present in the matrix of the granules), but further studies are required to determine whether the two molecules are already complexed with each other within the neutrophil.

Colloids↗
PubMed1990

Malignant histiocytosis. A reassessment of cases previously reported in 1975 based on paraffin section immunophenotyping studies.

Malignant histiocytosis (MH) is a term that has been used to describe a syndrome in which there is a systemic proliferation of cells that have the cytologic appearance of atypical histiocytes. Biopsy materials from 15 patients with malignant lymphoma diagnosed as malignant histiocytosis in a previous study reported in 1975 were analyzed by a panel of antibodies and reclassified using current nosologic concepts of malignant lymphoma. The antibodies used comprised reagents detecting a formalin-resistant epitope on B-cells (L26), T-cells (anti-CD3, anti-leu 22 [CD43], and UCHL1 [CD45RO]), monocyte/macrophage-derived cells (KP1 [CD68]), as well as antibodies that detect leukocyte common antigen (PD7 [CD45RB]), and a formalin-resistant epitope of Ki-1 (Ber-H2 [CD30]). The authors found that nine lymphomas had a profile consistent with T-lineage, including six in which Ki-1 (CD30) was coexpressed, and two were B-lineage. Three lymphomas showed no specific lineage characteristics although two were Ki-1 (CD30) positive, and none had expression of KP1 (CD68). The 12 lymph node biopsy specimens showed a variety of patterns of involvement, including sinusoidal, paracortical, and diffuse; the spleens showed predominantly red pulp involvement. A 15th case was believed most consistent with a virus-associated hemophagocytic syndrome. These findings support previous suggestions that the majority of cases diagnosed as MH represent T-lineage-associated hematolymphoid neoplasms, and that only a rare case will be of monocyte/macrophage origin. It is suggested that the term MH be subsumed under the rubric of large cell lymphoma and unless there are compelling immunohistochemical data to support a histiocytic origin, that the term MH be abandoned in favor of a more accurate descriptive term, such as sinusoidal large cell lymphoma.

Adolescent↗
PubMed1990

Different isoforms of human FcRII distinguished by CDw32 antibodies.

The Third and Fourth International Workshops on Leucocyte Differentiation Antigens identified six mAb, designated CDw32, reacting with human Ig FcR type II (FcRII). We have examined the immunohistochemical and immunocytologic reactivities of these antibodies and find that the antibodies could be divided into three classes of reactivity: 1) antibodies IV.3, CIKM3, and CIKM5 reacted with monocytes, macrophages and neutrophils; 2) antibodies KB61 and 41H.16 gave strong reactions with B lymphocytes, placental and hepatic endothelium, and weaker reactions with monocytes, macrophages, and neutrophils; 3) antibody 2E1 gave an intermediate reaction pattern. Immunoprecipitation from U937 cell lysates showed that antibodies KB61 and 41H.16 recognized Mr 41,000 and Mr 37,000 molecules whereas the other antibodies detected a Mr 42,000 molecule. Preclearing with antibody KB61 removed the Ag recognized by the other five antibodies confirming the identity of the Ag and demonstrating reactivity of KB61 with the Mr 42,000 molecule. Antibodies KB61 and 41H.16 precipitated a Mr 41,000 molecule from B lymphocytes. Flow cytometry and immunoprecipitation studies of cells transfected with cDNA clones coding for two isoforms of FcRII showed that all six of the antibodies react with both transfectants but the only immunoprecipitations were obtained using KB61 and 41H.16 and one of the transfectants. The protein sequence of KB61 Ag isolated from leukemic B cells showed close homology with the proteins encoded by the cDNA clones but diverged in the intracytoplasmic carboxyl-terminal region. It was concluded that preferential recognition of one or more of the numerous isoforms of FcRII underlies the differing reaction patterns of CDw32 antibodies.

Amino Acid Sequence↗