Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The glycoprotein gp51 of bovine leukaemia virus (BLV) has been included in an immunostimulating complex (ISCOM). The ISCOM was characterized biochemically in SDS-polyacrylamide gel electrophoresis showing the presence of proteins of estimated molecular weights of 50 and 30 kDa. Immunoblotting showed that gp51 was present in the ISCOM. The BLV-ISCOM had a S-value of 19 S and the electronmicrograph showed the cage-like structure as previously reported for other ISCOMs. About 17% of the total amount of gp51 in the cell culture fluid was recovered in the ISCOMs. The largest loss of gp51 was encountered during the sedimentation of the virus. An ELISA, utilizing monoclonal antibodies to defined epitopes for capture was developed to control the antigenicity of epitopes, e.g. those known to induce neutralizing antibodies. Using this device as a quality control for epitopes the following could be stated. First, ISCOMs prepared from virus solubilized with the non-ionic detergents Triton X-100 or MEGA did not react with neutralizing monoclonal antibodies. In contrast, ISCOMs prepared from virus solubilized with the non-ionic detergents Tween-20, Tween-80 or octyl glucoside did react with the neutralizing antibodies. Second, the neutralizing epitopes were better exposed in ISCOMs than the other epitopes of gp51. In a preliminary experiment it was shown that gp51 in ISCOMs was highly immunogenic.
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PMID:Bovine leukaemia virus ISCOMs: biochemical characterization. 254 75

By means of SDS PAGE we isolated from virus-infected foetal lamb kidney (FLK) cells a relatively homogenous envelope transmembrane protein gp30 of bovine leukaemia virus (BLV). As shown by a partial sequence analysis of the N-terminus of this protein, our gp30 preparation contained only traces (less than 5%) of p24 gag protein: Rabbit anti-gp30 serum did not cross react with the BLV proteins gp51, p12, p15(1), p15(2), and p10 but reacted weakly with the p24 polypeptide. 125I-labelled gp30 (chloramine-T) was precipitated with the serum of BLV-infected cattle. Nonlabelled preparation of gp30 competitively inhibited the reaction of 125I-labelled gp30 with the natural antibodies. We investigated 193 cattle sera by liquid phase radioimmunoassays (RIA) using 125I-gp30, gp51 and p24 antigens. Sixteen noninfected cattle sera were negative in all tests. The 177 serum samples of BLV-infected animals were examined to the diagnostic value of the three tests. Of these, 175 were positive in gp51 RIA, 172 in p24 RIA and 164 in gp30 RIA. In all three tests, 159 sera were positive while 18 sera, mostly coming from animals with normal leukocyte counts, were positive only either with gp51 or p24, or were double positive with either gp51/p24 or gp51/gp30. We conclude that the gp51 RIA is superior to both the gp30 and the p24 RIA and that the gp30 RIA will be useful for investigating the role of gp30 in virus pathogenicity.
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PMID:A radioimmunoassay detecting the bovine leukaemia virus transmembrane protein gp30 and anti-gp30 antibodies in the serum of cattle. 256 6

Apoprotein part of tissue factor of human placenta was purified 871 fold from the starting material with 4.2% yield by concanavalin A-Sepharose affinity chromatography and SDS-PAGE. The molecular weight of purified apoprotein was 45,000 in non-reduced condition and 49,000 in reduced condition. Tissue factor of human leukemia cells (FAB classification:M2 and M3) and cultured leukemia cell lines (HL-60 and Molt-4) was analyzed using specific rabbit anti-tissue factor IgG raised against purified material. Endotoxin stimulated HL-60 and Molt-4 also expressed procoagulant activity which was inhibited by tissue factor immune IgG. By immunostaining of the purified material, the lysate of leukemia cells (M2 and M3) and cultured leukemia cells (HL-60 and MOLT-4) revealed a major band of the same apparent molecular weight. Immuno-electron microscopic study on tissue factor of HL-60 cells produced the following findings: stimulation by endotoxin resulted in the formation of pseudopods of the cell membrane, and immunogold particles accumulated mainly on these pseudopods and cisternal spaces of rough endoplasmic reticulum, indicating exposure of the tissue factor to the surface of perturbed cell membrane with concurrent increase in tissue factor synthesis.
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PMID:Studies on leukemic cell tissue factor. 266 Mar 21

Immunostimulating complexes (ISCOMs) have been prepared from feline leukaemia virus (FeLV) envelope proteins. The ISCOMs were characterized biochemically in SDS-polyacrylamide gel electrophoresis showing the presence of proteins of estimated molecular weights of 15,000, 27,000 and 70,000. Immunoblotting showed that both the transmembrane protein p15E and the external glycoprotein gp70 (making up the gp85 protein) were present in the ISCOM. Furthermore, a degradation product of gp70 with an estimated molecular weight of 32,000 was identified in the immunoblot. The FeLV ISCOM was shown by electron microscopy to have the characteristic cage-like structure of an ISCOM with a mean diameter of 37 nm. About 10% of the total amount of gp70 in the culture fluid was recovered in the ISCOMs. The largest loss was encountered during the sedimentation of the virus. In a preliminary immunization experiment in mice the FeLV ISCOMs elicited after a booster gave a clear-cut immune response against gp70.
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PMID:Formation and characterization of FeLV ISCOMs. 275 Feb 72

Protein kinase C (PKC) was purified to near homogeneity from human leukemia ML-1 cells. The purified enzyme showed a single polypeptide band of 80 kDa on SDS-polyacrylamide gel after electrophoresis, and was totally dependent on Ca2+/phospholipid for activity. Diacylglycerol and the tumor-promoting on Ca2/phospholipid for activity. Diacylglycerol and the tumor-promoting phorbol esters stimulated the enzyme activity. Autophosphorylation of PKC purified from phenyl-Sepharose column showed both 80- and 37 kDa polypeptides. Further fractionation of PKC on a hydroxyapatite column revealed two peaks of enzyme activity, indicating that there may be two different forms of protein kinase C present in human leukemia cells. The purified PKC was used to phosphorylate RNA polymerase II of human leukemia cells in vitro and the autoradiogram showed that RNA polymerase II large subunits (240, 220 and 150 kDa) were phosphorylated in a time-dependent manner.
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PMID:Isolation and purification of protein kinase C from human leukemia ML-1 cells phosphorylation of human leukemia RNA polymerase II in vitro. 275 42

Human T leukemia cell line 81-66-45 spontaneously releases into the medium a suppressor lymphokine (SL), able to inhibit PHA-stimulated normal peripheral blood T cell proliferation. Ion exchange and gel filtration chromatography were used successfully to isolate and purify this immunosuppressive lymphokine from culture supernatants. When the purified suppressor lymphokine was characterized with SDS-polyacrylamide gel electrophoresis under reducing conditions, it was found to be a single protein chain of 66,000 daltons. Titration curves of the purified suppressor lymphokine indicated that the inhibitory activity is dose dependent. The suppressor lymphokine is cytostatic and its addition to the peripheral blood lymphocytes (PBL) did not change the cell number or cell viability. This factor was stable at pH 2.0-8.5 and at 56 degrees C for 30 minutes. The structural relationship of this lymphokine with other T cell factors is discussed.
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PMID:Purification of a suppressor lymphokine (SL) from a human T-cell line. 276 35

We report on membrane protein changes in an L1210 leukemia cell line with a highly specific defect in the function of the methotrexate (MTX)-tetrahydrofolate cofactor transport carrier. This clonal line, MTXrA, made 100-fold resistant to MTX, was derived in a single step and exhibited stable resistance over 120 generations in the absence of drug. The transport defect was associated with a 10-fold decrease in influx Vmax without a change in influx Km. There was no difference between the MTXrA and parent lines in the levels or affinities of specific cell surface binders for MTX nor in the labeling of the 44-kDa membrane protein upon treatment with the specific affinity label, N-hydroxysuccinimide ester of tritiated MTX. Consistent with impaired carrier function was the observation that trans-stimulation of MTX influx by intracellular 5-formyltetrahydrofolate observed in the parent line was not demonstrated in the MTXrA line. The transport defect was highly specific for the MTX-tetrahydrofolate cofactor transport carrier. Initial uptake rates for 5-fluoro-2'-deoxyuridine and 2-deoxyglucose were unchanged and influx and net transport of alpha-aminoisobutyric acid were, in fact, increased. There was no cross-resistance of this line to phenylalanine mustard or cytosine arabinoside, agents that utilize specific amino acid and nucleoside transport carriers, respectively. SDS-polyacrylamide gel electrophoresis of purified plasma membrane preparations stained with Coomassie Blue revealed several protein differences between the parental and MTXrA lines. Most prominent is a band at approximately 190 kDa which ran with slightly greater mobility than a lesser staining band in the parent line. [3H]Borohydride labeling of cells also identified a distinct protein peak in the MTXrA line at approximately 190 kDa eliminated by prior treatment of cells with neuraminidase. Absence of expression of protein or mRNA related to the multidrug resistance gene as well as lack of cross-resistance to daunorubicin or trimetrexate indicate that this mechanism of resistance to MTX is completely unrelated to the multidrug resistance phenomenon observed with high molecular weight heterocyclic compounds. These data represent the first demonstration of membrane protein differences in a highly resistant L1210 murine leukemia cell line with a marked unique defect in MTX transport which appears to be related to impaired mobility of the tetrahydrofolate-cofactor carrier. Further studies are now required to elucidate the possible role of one or more of these proteins in the transport defect.
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PMID:Membrane protein changes in an L1210 leukemia cell line with a translocation defect in the methotrexate-tetrahydrofolate cofactor transport carrier. 277 91

Binding of antigen to IgE-receptor complexes on the surface of RBL-2H3 rat basophilic leukemia cells is the first event leading to the release of cellular serotonin, histamine, and other mediators of allergic, asthmatic, and inflammatory responses. We have used dinitrophenol-conjugated bovine serum albumin (DNP-BSA) as well as the fluorescent antigen, DNP-B-phycoerythrin, and the electron-dense antigen, DNP-BSA-gold, to investigate dynamic membrane and cytoskeletal events associated with the release of [3H]serotonin from anti-DNP-IgE-primed RBL-2H3 cells. These multivalent antigens bind rapidly to cell surface IgE-receptor complexes. Their distribution is initially uniform, but within 2 min DNP-BSA-gold is found in coated pits and is subsequently internalized. Antigen internalization occurs in the presence and absence of extracellular Ca2+. The F-actin content of the detergent-extracted cell matrices analyzed by SDS PAGE decreases during the first 10-30 s of antigen binding and then increases by 1 min to almost double the control levels. A rapid and sustained increase is also observed when total F-actin is quantified by flow cytometry after binding of rhodamine-phalloidin. The antigen-stimulated increase in F-actin coincides with (and may cause) the transformation of the cell surface from a finely microvillous to a highly folded or plicated topography. Other early membrane responses include increased cell spreading and a 2-3-fold increase in the uptake of fluorescein-dextran by fluid pinocytosis. The surface and F-actin changes show the same dependence on DNP-protein concentration as stimulated [3H]serotonin release; and both the membrane responses and the release of mediators are terminated by the addition of the non-cross-linking monovalent ligand, DNP-lysine. These data indicate that the same antigen-stimulated transduction pathway controls both the membrane/cytoskeletal and secretory events. However, the membrane and actin responses to IgE-receptor cross-linking are independent of extracellular Ca2+ and are mimicked by phorbol myristate acetate, whereas ligand-dependent mediator release depends on extracellular Ca2+ and is mimicked by the Ca2+ ionophore A23187.
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PMID:Membrane and cytoskeletal changes associated with IgE-mediated serotonin release from rat basophilic leukemia cells. 293 14

Rat basophilic leukaemia (RBL) cells are known to possess three different kinds of receptors capable of interacting with IgE, which have been named R, H and 71K and which differ in apparent molecular weight (MW) as determined by SDS-PAGE. Reduction of receptors isolated from surface-iodinated RBL cells reduced the MW of 71K to a value corresponding to the MW of R without altering significantly the MW of H or R. Only a single reduction product of 71K could be detected when either surface-iodinated or 3H-leucine labelled RBL cells were used. Analysis of one- and two-dimensional tryptic peptide maps derived from surface-iodinated receptors revealed a similarity between R and 71K. The tryptic peptides of H exhibited an entirely different pattern. These results suggest that 71K consists either of two disulphide-linked R-like molecules, or of one such molecule linked to another as yet undetected polypeptide chain.
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PMID:Disulphide-linked receptors for IgE on rat basophilic leukaemia cells. 294 66

Adult T-cell leukemia virus is the member of a human type-C retrovirus family (HTLV) found to be associated with adult T-cell leukemia (ATL) in Japan. In our study, HTLV was isolated from the MT-2 cell line, purified on sucrose gradient and labelled with fluorescein-isothiocyanate (FITC-HTLV). The protein pattern of the virus was determined by SDS-gel electrophoresis and assured by Western blotting using ATL patient serum. Fresh human lymphocytes, separated B and T cells, mouse and rabbit lymphocytes, mouse fibroblasts, and 13 different tumor cell lines were tested in parallel for binding of FITC-HTLV and infectability by the virus. Virus binding to cell receptors was assayed by flow cytometry. Successful infection was monitored by following the expression of HTLV-determined antigen (HTLA). Most of the cells bound FITC-HTLV at levels ranging from 5% to 130% of the MT-2 cell binding. Only fresh human T, mouse and rabbit lymphocytes were infectable by cell-free virus preparations. The results demonstrate that HTLV receptors are present on different types of cells of both human and animal origin, and that infection by the virus is restricted to fewer host cells but not limited to a specific class of human lymphocytes.
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PMID:Host cell range of adult T-cell leukemia virus. I. Viral infectivity and binding to various cells as detected by flow cytometry. 299 Nov 47


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