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C M Steel

Publications and source records attributed to C M Steel.

At least 145 records · Page 8Linked to original sources
PubMed1984

The use of detergents in velocity sedimentation of cell culture IgM.

The biosynthetically radiolabelled secreted proteins of human lymphoblastoid cell lines have been analysed by sucrose gradient velocity sedimentation. The addition of detergent to the gradient buffer dramatically improves the recovery of immunoglobulins from cell line supernatants, allowing the gradient fractions to be analysed further both serologically and biochemically. The results of these analyses show that IgM is synthesised in the 19S form and can be clearly separated from other components which include free light chains. Immunoglobulin appears to form a much larger portion of the proteins secreted by human lymphoblastoid lines than has formerly been recognised, a finding which may be of practical importance for the development and exploitation of human monoclonal antibodies.

Carbon Radioisotopes↗
PubMed1984

Correlation between tumorigenicity and altered glycosylation of a "leukocyte common" antigen in human lymphoid cell lines.

Five human lymphoblastoid cell lines which have become tumorigenic, as judged by transplantability into immunosuppressed mice, have been compared with earlier, non-tumorigenic stocks of the same cultures, recovered from liquid nitrogen. Analysis of the cell surface glycoproteins by SDS-PAGE, electro-transfer to cellulose nitrate and "blotting" with radioiodinated lectins, reveals an increase in the molecular weight of one band from around 190 kd to 220 kd, in each case coinciding with the acquisition of the tumorigenic phenotype. Probing the electrotransfers with a monoclonal antibody demonstrates that the altered glycoprotein is a member of the "leukocyte common antigen" family. The increase in molecular weight is due to the addition of carbohydrate residues which are removed by treatment with neuraminidase and endoglycosidase. Screening a larger number of lymphoid cell lines, including those derived from Burkitt's lymphoma, shows an excellent correlation between tumorigenicity and altered molecular weight of a leukocyte common antigen.

Animals↗
PubMed1984

Tumorigenicity of human lymphoblastoid cell lines, acquired during in vitro culture and associated with chromosome gains.

Tumorigenicity of human lymphoma and lymphoblastoid B-cell lines was assessed by their ability to form growing and transplantable masses on subcutaneous inoculation into neonatally thymectomized, Ara-C-protected, total-body-irradiated mice. By these criteria, 12 lines of known malignant origin were tumorigenic, 11 lymphoblastoid lines, tested after less than one year of in vitro growth, were non-tumorigenic and 8/18 long-established lymphoblastoid lines produced transplantable tumours. All of the long-established lines had acquired karyotypic changes on prolonged culture, the predominant characteristic being a gain of whole chromosomes or of major chromosome segments. None showed the classical 8:14 translocation associated with Burkitt's lymphoma. Comparisons with nontumorigenic precursors (recovered from liquid nitrogen storage) and with other non-tumorigenic but chromosomally abnormal, lymphoblastoid lines suggest that imbalance of the dosage of genes carried on chromosomes 7,8 and 9 may be important in determining the tumorigenic phenotype.

Alleles↗
PubMed1984

Abnormalities of circulating lymphocyte subsets in haemophiliacs in an AIDS-free population.

Markers of the immune system were examined in 47 patients with haemophilia A and B who had been treated exclusively with blood products from a population apparently free from acquired immunodeficiency syndrome (AIDS). In haemophilia A the absolute number of T helper cells was depressed, resulting in a reduction in the helper/suppressor ratio in about half the patients. The serum IgG and IgA concentrations were raised and the serum IgG correlated with serum alanine aminotransferase. In haemophilia B, the helper/suppressor ratio was also depressed but this was attributable to a slight increase in the mean suppressor cell number and a slight decrease in the helper cells. These observations suggest that the abnormalities result from transfusion of foreign proteins and not from a specific infective agent and, further, that individuals may differ in susceptibility to the induced disturbances of immunity.

Acquired Immunodeficiency Syndrome↗
PubMed1984

T-cell proliferation and expression of MHC class II antigens.

Two monoclonal antibodies to major histocompatibility complex (MHC) class II antigens, which in combination identify beta chains encoded by the SB and DR loci, were used to investigate which of these gene products were expressed at the cell surface of unstimulated T cells and at various stages of mitogen-induced T-cell maturation. In tests on blood lymphocytes from healthy donors 12% of T cells expressed class II antigens, but only SB antigens were expressed. During activation of T lymphocytes, SB-coded antigens were expressed before DR antigens, and the kinetics of SB expression correlated with the proliferative response of T cells. These results and consideration of recent reports from other laboratories lead us to suggest that SB-coded class II antigens play a role in T-cell proliferation.

Cells, Cultured↗
PubMed1984

Beta-adrenoceptor binding defects in cell lines from families with manic-depressive disorder.

Binding of 125I-iodohydroxybenzylpindolol to beta-adrenoceptors has been examined in lymphoblastoid cell lines from members of 5 families affected by manic-depressive disorder. Cell lines from 6 manic-depressives, 7 unaffected relatives and 11 non-psychiatric controls were examined. Binding was reduced to less than half of control values in cell lines from 4 out of 6 manic-depressives and only 1 out of 18 unaffected relatives or controls. All the cell lines with reduced beta-adrenoceptor binding came from 3 families; members of the remaining 2 families showed normal binding. These findings suggest that genetic heterogeneity is present in manic-depressive disorder and that a beta-adrenoceptor defect may influence genetic susceptibility to the disorder.

5'-Nucleotidase↗
PubMed1983

Methods of detecting mature human Ia-like antigen and their metabolic precursors.

Ia antigens were shown to be present in the cell almost exclusively as mature alpha beta dimers which split into separate alpha and beta chains after boiling in SDS. In contrast metabolically labelling the cells with [35S]methionine resulted in only free alpha and beta chains being labelled. It is concluded that this widely used type of labelling, although useful for studying intermediate synthesis, should not be used for labelling mature cell surface molecules.

Carbon Radioisotopes↗
PubMed1983

Enhanced expression of human Ia antigens by chronic lymphocytic leukemia cells following treatment with 12-O-tetradecanoylphorbol-13-acetate.

Using a panel of monoclonal antibodies which detect framework determinants of human-Ia alpha and beta polypeptides and the DC-specific monoclonal antibody Genox 353, the in vitro effects of 12-O-tetradecanoylphorbol-13-acetate (TPA) on the expression of Ia antigens by cells from chronic lymphocytic leukemia (CLL) patients have been studied. In all subjects studied a great increase in expression of framework Ia determinants was found following culture of CLL cells for 90 h with TPA at 10(-7) g/ml. TPA treatment of CLL cells also induced increased expression of Genox 353+ antigens, in some cases where Genox 353 binding was either negligible or not detectable in cells cultured in the absence of TPA.

Antibodies, Monoclonal↗
PubMed1983

Detection of Ia epitopes by monoclonal antibody blotting.

Monoclonal antibodies directed against human Ia alpha- and beta-subunit chains have been used as probes to detect polypeptides carrying recognized antigenic determinants or epitopes following two-dimensional PAGE separation. Approximately 4 sets of components differing in isoelectric point but not in molecular weight are recognized by each antibody. The anti-alpha-chain, McAb, reacts weakly with spots designated as epsilon but neither antibody recognizes Im, Ii or delta determinants under the conditions tested.

Antibodies, Monoclonal↗
PubMed1983

Spontaneous and mutagen induced sister chromatid exchange in multiple sclerosis.

Spontaneous and mutagen induced sister chromatid exchange (SCE) frequencies have been studied in nine patients with multiple sclerosis and in nine age and sex matched healthy controls. The incidence of spontaneous SCE in lymphocytes of the MS patients was significantly greater, by about 50%, than in those of the control subjects. When exposed to mitomycin C (MMC) or ethyl methane sulfonate (EMS) in vitro, cells from both groups showed typical dose dependent increases in SCE frequency, with yields from MS patients slightly higher than from controls. The higher SCE yields in mutagen treated MS cells relative to controls is considered to reflect initial basal differences between the cell types, so that MS cells are not intrinsically hypersensitive to mutagen treatment.

Adult↗
PubMed1983

Biochemical variation of human Ia like antigens detected with monoclonal antibodies.

Four mouse monoclonal antibodies to human B cell surface determinants previously described as being directed against Ia like (MHC class II) antigens, have been shown to precipitate Ia alpha and beta chains. Electrophoretic transfer experiments showed one antibody to be directed against Ia alpha chains and two others to be against Ia beta chains. The antibodies were then used to analyse a range of cell types and a large number of lymphoblastoid and lymphoma cell lines. Ia antigens could not be detected on peripheral blood T cells, cord endothelium or T cell lines but their presence was confirmed on activated T cells and peripheral blood non-T cells. There was both qualitative and quantitative variation of Ia like antigen expression on B cell lines, including an apparent genetic polymorphism in alpha chain structure unrelated to DR allotypes and a single instance of a beta chain of abnormally high molecular weight.

Antibodies, Monoclonal↗
PubMed1983

Phytohaemagglutinin-induced proliferation of human T lymphocytes: differences between neonate and adults in accessory cell requirements.

The accessory cell requirements of human neonatal T lymphocytes were compared with those of adult T lymphocytes in lectin-induced polyclonal activation. It was found that purified neonatal Esh rosette positive lymphocytes were not activated into a proliferative response by the lectin phytohaemagglutinin (PHA), by phorbol ester (TPA) or by conditioned medium containing T cell growth factor activity (TCGF-CM). A proliferative response to PHA was obtained in the presence of a suitable accessory cell (AC) such as the plastic adherent, monocyte enriched population or the sIg positive lymphocyte population, both of which were shown by cellular titrations to be equally effective. Optimal proliferative responses to PHA could also be obtained, in the absence of accessory cells, by addition of TPA or TCGF-CM. Neonatal T lymphocytes gave highly reproducible responses and this could be achieved effectively by simple separation procedures not involving further subfractionation of the responding Esh+ lymphocyte population. The exquisite accessory cell dependence of these cells demonstrated in this investigation provides a readily available human model system for the evaluation of the variables involved in T lymphocyte activation and a sensitive assay for measuring accessory cell activity.

Adult↗
PubMed1982

Differential expression and serologically distinct subpopulations of human Ia antigens detected with monoclonal antibodies to Ia alpha and beta chains.

Studies with two monoclonal antibodies (DA6.147 and DA6.231) which react, respectively, with isolated human Ia alpha and beta chains are reported. Both antibodies detect epitopes expressed on all DR-heterozygous and DR-homozygous cell lines tested (n = 17) and bind to the Epstein-Barr virus-negative cell line Ramos. Ia subunit specificity of the antibodies was determined by an adaptation of an electroblot technique which transfers separated Ia chains from polyacrylamide gels to nitrocellulose paper. In radioimmunobinding assays, peripheral blood B cell-enriched fractions, phytohemagglutinin-activated T cells and pokeweed mitogen-activated cells gave strong reactions with DA6.231 (anti-Ia beta). In contrast, DA6.147 (anti-Ia alpha) reacted only weakly, if at all, with peripheral B cells, pokeweed mitogen blasts and activated T cells. However, both antibodies bound to isolated Ia from activated T cells and peripheral B cells after Nonidet-P40 solubilization of the cells and DA6.147+ antigens could be found in the cytoplasm of activated T cells by indirect immunofluorescence techniques. Results of serological inhibition procedures following fractionation of lymphoblastoid cell lysates on monoclonal antibody affinity columns showed that the DA6.147 alpha chain epitope is carried on only a minor subpopulation of human Ia.

Antibodies, Monoclonal↗
PubMed1982

Human MHC class II molecules as differentiation markers.

DA6.231 and DA6.164 are mouse monoclonal antibodies that immunoprecipitate HLA-DR-like p34,29 glycoprotein dimers from surface- and metabolically-labeled cells. On lymphoblastoid cell lines the distribution of the 231 epitope is completely nonpolymorphic, while the 164 epitope is present on all cells except on those that are DR7 homozygous. Binding-inhibition studies show that the 231 and 164 epitopes are spatially close to each other when present on the same molecule. The mutual inhibition pattern and the absence of the 164 epitope from the 231+ cells of a few leukemia patients suggest, however, that 231 and 164 epitopes are not invariably present together. Most DR-positive cells possess 231+ and 164+ and 231+ 164- class II molecules in approximately a 2:1 ratio. This has been confirmed by immune depletion studies. Thus DA6.231 appears to define a supralocus epitope. The 164 epitope may be a marker for a subset of class II molecules exhibiting differential expression on various cell types immortalized by malignant transformation.

Antibodies, Monoclonal↗