Biomedical subjects

R A Robins

Publications and source records attributed to R A Robins.

At least 91 records · Page 5Linked to original sources

PubMed1985

Multiple epitopes on a human breast-carcinoma-associated antigen.

The monoclonal antibody (MAb) NCRC-11 identifies an epitope expressed variably in human breast cancer. The degree of expression of this epitope in primary operable tumours is closely related to the subsequent clinical course of the disease (Ellis et al., 1985). The target antigen for NCRC-11 was isolated from subcellular membranes of breast carcinomas and purified by immunoadsorbent chromatography. NCRC-11 epitopes were expressed upon a large glycoprotein of more than 400 kd. This material was susceptible to degradation by pronase and papain and contained N-acetylglucosamine, as indicated by its binding to wheat-germ agglutinin. The NCRC-11-defined antigen expressed epitopes for the anti-human milk-fat globule membrane antibodies HMFG-1 and HMFG-2, and other antibodies against epithelial membrane antigens (EMA, LICR-LON-M8). The reactivity of these antibodies with tumour membranes was also similar, but not identical, to that of the NCRC-11 antibody. In competitive binding-inhibition assays, these antibodies partially inhibited the binding of 125I-NCRC-11 antibody to antigen, suggesting that the epitopes involved are topographically closely associated. Sandwich immunoassays demonstrated that NCRC-11 epitopes are likely to represent repeated structures of the NCRC-11 antigen. The findings presented are interpreted as indicating that the NCRC-11 antigen expresses a variety of epitopes which are associated with normal differentiation and malignant change.

Animals↗

PubMed1985

A flow cytometric method for the measurement of phagocytosis by polymorphonuclear leucocytes.

A new method for the measurement of phagocytosis of Candida albicans by human polymorphonuclear leucocytes (PMN) is described using a fluorescence activated cell sorter. We have used acridine orange to discriminate between PMN which have internalised yeast particles and those which have not. This method allows accurate measurement of particle phagocytosis as an event distinct from particle adherence. It also permits detailed examination of the kinetics of phagocytosis, the study of which is likely to be of value in the investigation of diseases where abnormalities of PMN function are suspected.

Acridine Orange↗

PubMed1985

The influence of tumour cell DNA abnormalities on survival in colorectal cancer.

The cellular DNA content was measured from paraffin-embedded material in 134 colorectal cancers from patients in whom the outcome was known. Seventy-two (55 per cent) were found to contain cells with abnormal DNA (DNA aneuploid). The presence of such a population of cells was not related to pathological stage or histological grade. However, only 14 (19 per cent) patients with DNA aneuploid tumours survived 5 years compared with 27 (43 per cent) of patients with diploid tumours (chi 2 = 8.0, P = 0.005). Stepwise logistic analysis showed cellular DNA content to be an important prognostic factor in colorectal cancer, independent of pathological stage and histological grade.

Aneuploidy↗

PubMed1985

Kinetics of divalent monoclonal antibody binding to tumour cell surface antigens using flow cytometry: standardization and mathematical analysis.

Flow cytofluorimetric methods have been used to quantitate the interaction between a divalent monoclonal antibody and a tumour cell surface antigen. After standardization using fluorescein and 125I-labelled antibodies, kinetics of association and dissociation were measured, and antibody bound at equilibrium quantitated. A mathematical model was developed in conjunction with these experimental results which allowed the calculation of rates for monovalent association and monovalent and divalent dissociation, and a description of the contribution of each to the level of bound antibody at different antibody concns.

Antibodies, Monoclonal↗

PubMed1985

Pleomorphic T-cell leukaemia in a Caucasian adult: clinical phenotypic and functional characteristics.

Pleomorphic T-cell leukaemia occurring in an adult Caucasian patient is described. The leukaemia cells expressed both antigenic determinants (T4 and T8) normally detected separately on either helper or suppressor cells. They functioned as helper cells and there was evidence of unbridled antibody production. It is possible that a distinctive subtype of pleomorphic T-cell leukaemia occurs in Caucasian patients.

Epitopes↗

PubMed1984

The expression of glycoproteins on single blood platelets from healthy individuals and from patients with congenital bleeding disorders.

Glycoproteins present on the surface of blood platelets are fundamental to normal blood platelet behaviour. We have used monoclonal antibodies and flow cytofluorimetry to study the expression of glycoproteins on single platelets from normal subjects, and from patients with Glanzmann's thrombasthenia and the Bernard-Soulier syndrome. We show that normal platelets are heterogeneous in that individual cells display markedly different numbers of glycoprotein IIb/IIIa complex and glycoprotein Ib molecules. We also show that the two congenital bleeding disorders are associated with markedly reduced numbers of glycoprotein IIb/IIIa complex or glycoprotein Ib molecules on all the platelets rather than the difference residing in a sub-population.

Blood Platelets↗

PubMed1984

Characteristics of the cell surface antigen, p72, associated with a variety of human tumours and mitogen-stimulated T-lymphoblasts.

The monoclonal antibody 791T /36, prepared against a human osteogenic sarcoma cell line, 791T , reacts with a variety of human tumours and also mitogen-stimulated PBMN cells. The target antigen as expressed upon 791T cells is a monomeric plasma membrane-associated glycoprotein with an apparent Mr of 72000. By quantitative flow cytofluorimetry, approx. 10(5) antibody molecules bound per cell to T-lymphoblasts induced with PHA or Con A, whereas only a few thousand antibody molecules bound per cell to unstimulated cells, so that the antigen may be classified as a lymphocyte activation antigen. On lymphoblasts, the 791T /36 again reacted with a protein with an apparent Mr of 72000. This antigen therefore has a dual role as a tumour marker and lymphocyte activation antigen which may be implicated in the regulation of cell proliferation.

Antibodies, Monoclonal↗

PubMed1984

Natural killer cells in renal allograft rejection.

Monoclonal antibody Anti Leu 7 has been used to enumerate peripheral blood NK cells in 20 renal allograft recipients. Blood was taken preoperatively and three times per week for the first month after transplantation; separated mononuclear cells were stained with Anti Leu 7 then analysed on a fluorescence activated cell sorter. Results were related to acute rejection episodes diagnosed clinically and confirmed by Trucut biopsy of grafts. A reduction in the number of Leu 7 positive cells occurred postoperatively. Nineteen out of 20 patients showed a rise in number of circulating NK cells during acute rejection episodes.

Antibodies, Monoclonal↗

PubMed1984

Flow cytometric analysis of proflavine uptake into normal rat hepatocytes and cells arising during AAF-induced hepatocarcinogenesis.

The uptake of the fluorescent drug proflavine was measured in suspensions of hepatocytes from normal and carcinogen (2-acetylaminofluorine, AAF)-fed rats by flow cytometry. Drug uptake into hepatocytes from carcinogen-fed animals was consistently lower than that into hepatocytes from normal animals. Isolated nuclei, prepared from the livers of normal and AAF-fed rats showed similar proflavine uptake. Drug uptake into hepatocytes from AAF-fed animals, however, was increased by prior exposure to a metabolic inhibitor. Thus, differences in drug uptake may reflect changes in the cell membrane, together with an alteration in the metabolic integrity of the cells. The uptake of drug in hepatocytes from AAF-fed rats was uniformly low within each cell preparation. However, drug uptake varied not only between tumours arising in the livers of these animals but also within each tumour cell preparation. This study indicates that flow cytometry can provide an effective means for analysing drug uptake into cell populations arising during hepatocarcinogenesis.

2-Acetylaminofluorene↗

PubMed1984

A monoclonal antibody, NCRC-11, raised to human breast carcinoma. 1. Production and immunohistological characterization.

The production of a mouse monoclonal IgM antibody, NCRC-11, raised against human breast carcinoma is described. It has been characterized immunohistologically. The antigen recognised has a wide but highly specific distribution in normal tissues, being virtually confined to the surface of certain epithelial cell types. It is found in some forms of epithelial metaplasia and most epithelial malignancies, particularly adenocarcinomas. The heterogeneity of staining in mammary carcinomas is outlined and is of particular interest. The immunohistological staining distribution of NCRC-11 is similar to other antibodies, including anti-epithelial membrane antigen, which were raised against human milk fat globule membrane. A competition experiment with some of these antibodies, using a flow cytofluorimeter, showed competition with one antibody, LICR LON/M8.

Antibodies, Monoclonal↗

PubMed1984

In vitro activation of natural killer-like cytotoxicity by specifically in vivo primed T-helper lymphocytes in the rat.

The interaction between the rat non-cytotoxic T lymphocyte subset, which is marked by the W3/25 monoclonal antibody, and natural killer cells was investigated. Specifically in vivo primed lymph node cells were restimulated in vitro with the priming antigen and co-cultured with a source of natural killer cells and their precursors. Cytotoxic activity, generated during a 4 day incubation period, was assessed by lysis of a rat natural killer cell-sensitive tumour target cell line, y3Ag123. This cytotoxic activity was more fully described as natural killer cell cytotoxicity on the basis of target cell specificity, using a range of natural killer cell-susceptible and -resistant targets. The W3/25-positive T cell, separated from the in vivo primed lymph node cells by nylon wool column elution, antibody labelling and sorting on the fluorescence-activated cell sorter, was shown to be necessary to stimulate the generation of this activity. W3/25-negative cells were not active in this respect. The activation was shown to be mediated via lymphokine(s), probably interleukin-2, present in concanavalin A-induced lymphocyte culture supernatants. These supernatants could be used to substitute for in vivo primed, restimulated W3/25-positive lymph node cells in activating natural killer cell cytotoxicity from normal spleen cells. Nylon wool column-eluted spleen cells, activated in vitro with conditioned medium were separated into OX8-positive and OX8-negative subsets using the fluorescence-activated cell sorter. The distribution of cytotoxic activity related to that of freshly derived rat natural killer cells.

Animals↗

PubMed1984

Phenotype of cytotoxic effector cells infiltrating a transplanted, chemically induced rat sarcoma.

Previous work from this laboratory indicated that methylcholanthrene-induced sarcomas in the rat are infiltrated by cells with the cytotoxic properties of natural killer (NK) cells. Using a combination of velocity sedimentation and analysis and separation in the fluorescence-activated cell sorter, it has been possible to isolate and characterize these putative NK cells. The present results confirm that cytotoxicity is restricted to NK-sensitive targets (syngeneic, allogeneic and xenogeneic) and no evidence was found for cytotoxic T lymphocytes (CTL). In addition, effector cells have the morphology of large granular lymphocytes, and the pattern of expression of five monoclonal antibody-defined surface markers is identical with that of normal splenic NK cells.

Animals↗

PubMed1983

Characteristics of a cell surface antigen defined by an anti-human osteogenic sarcoma monoclonal antibody.

The expression of a cell surface antigen defined by an anti-human osteogenic sarcoma monoclonal antibody was analysed by flow cytofluorometry using fluorescein-labelled antibody. Quantitative absorption tests established that the antigen was associated with plasma membranes, whereas cytosol, cellular lipids and nuclei were largely devoid of activity. Single-phase aqueous butanol solutions at non-cytolytic concentrations failed to solubilize the antigen, although treatment of cells with papain virtually abolished antigenic activity. The antigen was shown to be solubilized by the non-ionic detergent Nonidet P-40, and following lactoperoxidase-catalysed radioiodination of viable cells, extraction with detergent, immunoprecipitation of antigen with monoclonal antibody and Sepharose-Protein A, the molecular weight of antigen was determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The findings indicate that this human osteogenic sarcoma antigen is a monomeric integral membrane protein with an apparent molecular weight of 72,000, which is predominantly expressed at the external face of the tumour cell plasma membrane.

Antibodies, Monoclonal↗

PubMed1983

A comparison of membrane markers on rat cytotoxic cells.

The antigenic characteristics of cytotoxic T cells (CTL) and cells mediating antibody-dependent cellular cytotoxicity (ADCC) were defined using monoclonal antibodies W3/13, W3/25 and MRC OX8, and compared with the phenotype of natural killer (NK) cells previously defined by these antibodies. CTL, ADCC effector cells and NK cells were also tested for expression of Ia antigen using MRC OX6 monoclonal antibody. The fluorescence-activated cell sorter was used to separate effector populations into antigen-positive and antigen-negative subsets, and the cytotoxicity of the resultant lymphocyte fractions was then assessed using 6 hr 51Cr release assay and a quantitative method of analysis based on consideration of target cell lysis as an enzyme substrate reaction. CTL, ADCC effector cells and NK cells were W3/25 negative and OX6 negative. CTL were positive for W3/13 and OX8 antibody with no cytotoxicity in the W3/13 negative and OX8 negative fractions. In contrast, ADCC effector cells showed heterogeneity of staining with W3/13 and OX8 antibodies, with 50% cytotoxic activity in the W3/13 negative fraction, and 20-30% cytotoxic activity in the OX8 negative fraction. In parallel experiments, NK cells and ADCC effector cells showed identical marker heterogeneity when tested with W3/13 and OX8 antibodies.

Animals↗

PubMed1983