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 15,000-molecular-weight polypeptide (p15) of feline leukemia virus (FeLV) was shown to impair normal lymphocyte function in vitro and to abrogate immunity to feline oncornavirus disease in vivo. FeLVp15 suppressed concanavalin A-induced blast transformation of normal feline lymphocytes by 68%, while other virion proteins had no effect. p15 suppression was not due to toxicity, nor was p15 a competitive inhibitor of concanavalin A binding. Capping of receptors for concanavalin A on normal feline lymphocytes also was inhibited by either inactivated FeLV or FeLV p15. Groups of cats were immunized with either killed feline oncornavirus-associated cell membrane antigen bearing tumor cells or tumor cells plus FeLV p15. After challenge with feline sarcoma virus, three of four p15-treated cats developed progressive fatal fibrosarcoma as compared to one of five non-p15-treated cats. The cats receiving p15 also had lower cytotoxic antibody titers against feline oncornavirus-associated cell membrane antigen (mean peak titer, 1:6) than did the non-p15 group (1:74). These data support the hypothesis that the immunosuppression in cats infected with FeLV is mediated by FeLV p15.
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PMID:Immunosuppressive properties of a virion polypeptide, a 15,000-dalton protein, from feline leukemia virus. 21 25

The glycopeptides obtained by pronase digestion of two ecotropic strains of murine leukemia virus (MuLV) were compared by gel filtration. Four different glycopeptide size classes, designated G(1), G(2), G(3), and G(4), with molecular weights of approximately 5,100, 2,900, 2,200, and 1,500, respectively, were shown to be associated with Rauscher MuLV virions grown in JLS-V9 cells. Various sugar precursors, including glucosamine, galactose, fucose, and mannose were incorporated into G(1) and G(2), suggesting that these are complex (type I) glycopeptides. The two smaller glycopeptide size classes, G(3) and G(4), were shown to be mannoserich (type II) glycopeptides. G(4) was more sensitive to digestion with endo-beta-N-acetylglucosaminidase H than G(3), suggesting that the core of G(3) may contain fewer mannose residues. Glycopeptides of the same size class as G(1) and G(2) were associated with both Rauscher MuLV and AKR-MuLV grown in III6A (mouse embryo) cells. Previous studies have shown that gp52, a proteolytic cleavage product of gp70, possessed primarily G(1) glycopeptides and that gp52 was more highly sulfated than gp70. We observed that G(1) is approximately twofold more highly sulfated than G(2), explaining the observed difference in sulfation of gp52. The unusually large size of G(1) suggested that infection with MuLV may alter the host cell glycosylation pattern. To test this possibility, glycopeptides from Sindbis virions grown in uninfected and Rauscher MuLV-infected JLS-V9 cells were compared, and no differences were observed. G(1) was not detected in Sindbis virions, indicating that acquisition of G(1) depends on properties of the virus-coded polypeptide backbone of the gp70 molecule.
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PMID:Glycopeptides of murine leukemia viruses. I. Comparison of two ecotropic viruses. 22 50

This work describes the detection, isolation, and partial characterization of a BALB/c mouse fibroblast cell surface antigen. This antigen migrates as a polypeptide of approximately 100,000 daltons in a discontinuous sodium dodecyl sulfate/polyacrylamide gel electrophoresis system, can be labeled by either lactoperoxidase-catalyzed cell surface 125I iodination or metabolic incorporation of [3H]glucosamine, and can be isolated by concanavalin A affinity chromatography. This cell surface glycoprotein is antigenic in BALB/c mice and has been correlated with the rejection of immunogenic tumor cells. Also, antiserum specific for Moloney leukemia virus precipitates the 100,000-dalton cell surface protein from viral and immunogenic spontaneous transformants. This virus-related antigen comigrates on sodium dodecyl sulfate gels with the major iodinated cell surface protein of these transformants. Rabbit antiserum to the purified antigen demonstrates a marked preference for the surfaces of immunogenic tumor cells as compared with normal cells and nonimmunogenic tumor cells.
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PMID:Isolation and characterization of a tumor cell surface antigen from spontaneously transformed BALB/c mouse fibroblasts. 28 13

Antisera were raised in New Zealand White rabbits against non-B, non-T acute lymphocytic leukemia (ALL) cells coated with antilymphocyte serum. Following minimal absorption with chronic lymphocytic leukemia (CLL) cells, the antiserum reacted mainly with non-B, non-T ALL cells. The following numbers of patients had leukemia cells that reacted with the ALL antisera: 13 of 18 with ALL, 3 of 27 with acute myelocytic leukemia, 1 of 8 with chronic myelocytic leukemia (CML), and 0 of 12 with CLL. The positive CML was a patient in CML blast crisis. Normal peripheral blood B- and T-lymphocytes and normal bone marrow were negative. Reactions of the anti-ALL serum (136K) were compared with the reactions of a rabbit anti-B-cell antiserum (63K) that reacted with approximately 70% of leukemia cells. Cultured lymphoblastoid cell lines from normal donors were negative by both cytotoxicity and immunofluorescence tests. However, by immunofluorescence testing, 8 of 17 known malignant lines from a variety of lymphoproliferative disorders were positive; 4 of these lines were of T-cell origin. By immunoprecipitation and polyacrylamide gel electrophoresis, the ALL antigen appeared to consist of a single polypeptide chain of approximately 98,000 daltons. The anti-ALL antiserum was not cytotoxic for normal myeloid stem cells (colony-forming units).
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PMID:Acute lymphocytic leukemia-associated cell membrane antigen. 30 2

Thymus-leukemia (TL) antigens are expressed in murine lymphocytes under strict developmental regulation. To elucidate the molecular basis of TL expression, we have identified the molecular species that react with TL antiserum. At least three species can be resolved by metabolic radiolabeling of thymocytes and ASL1 leukemia cells, lysis, immune precipitation, and sodium dodecyl sulfate-polyacrylamide. After a brief incubation with [35S]methionine, the only radioactive molecule recognized by TL antiserum is a homogeneous species with an apparent Mr of 45,000 daltons. This molecule, 45K TL, includes high-mannose-type carbohydrate attached to a 45,000 dalton glycosidase-resistant backbone. In this form, 45K, it is never exposed on the cell surface. If pulse-labeled cells are further incubated with nonradioactive methionine before lysis, however, radioactivity disappears from the 45K TL species and appears in the slower migrating species 46K and 48K TL. Thus, 46K and 48K appear to represent products generated from the 45K TL precursor by posttranslational modification. These TL forms are displayed on the cell surface; they lack high-mannose carbohydrate but evidently include acidic complex-type carbohydrate. Normal thymocytes from Qa:Tla-negative mice lack not only the surface forms of TL but also the intracellular 45K TL form. Peripheral lymphoid cells of Qa:Tla-positive mice synthesize none of these TL species. But the TL antiserum, which contains Qa antibody, recognizes a distinct gene product in spleen and thymus of Qa-Tla-positive mice. In its pulse-labeled form, this molecule, which may represent Qa-1, has an apparent Mr of 44,000 daltons, and consists of a glycosidase-resistant polypeptide core of only 35,000 daltons linked to more high mannose carbohydrate than 45K TL.
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PMID:Synthesis and processing of molecules bearing thymus leukemia antigen. 31 85

A series of mouse hybridomas producing monoclonal antibodies against human acute lymphocytic leukemia (ALL) cells was generated and screened for tumor specificity. Among 1200 primary cultures, 60 produced an antibody that could distinguish between the immunizing leukemia cells and an isologous B lymphoblastoid cell line. Of these, two produced an antibody that detects an antigen expressed preferentially on ALL cells and on a subpopulation of normal cells found in the cortex of the thymus. Other normal human lymphoid cells from lymph nodes, spleen, bone marrow, and peripheral blood express only low levels of this antigen. High levels of this "thymus-leukemia" antigen were found on T-ALL cells, T-ALL-derived cell lines, and some "null" ALL cells. By contrast, B-cell leukemias, B lymphoblastoid cell lines, and normal and malignant myeloid cells contain either low or undetectable amounts of this antigen. The thymus-leukemia antigen has been isolated from the membranes of leukemia cells by detergent solubilization and subsequent immunoprecipitation with the monoclonal antibody. Preliminary biochemical characterization shows the antigen to be associated with a polypeptide of Mr approximately 28,000.
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PMID:A human thymus-leukemia antigen defined by hybridoma monoclonal antibodies. 31 41

The envelope glycoproteins (designated gp70 and gp45) of the Rauscher strain of murine leukemia virus were solubilized by osmotic shock and freeze-thawing in chaotropic solutions. The viral glycoproteins were then purified by phosphocellulose chromatography and gel permeation chromatography on Bio-Gel A-1.5m. Yields by this procedure were 6.2% for gp70 and 1.3% for gp45 on a protein input basis. The apparent molecular weights were respectively 67 500 and 47 500 with a polypeptide chain molecular weight of approximately 45 000 for both glycoproteins. Amino acid analysis showed a high degree of similarity for both components, with some differences subject to further evaluation. The total carbohydrate content was approximately 32% for gp70 and 6-9% for gp45. In keeping with the amino acid compositional similarity suggesting relationships, alanine was found to ba the amino-terminal amino acid of both glycoproteins, and cross-reactivity was demonstrated by immunologic tests. The data suggest that the chief difference between gp70 and gp45 lies in the carbohydrate content.
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PMID:Envelope glycoproteins of Rauscher murine leukemia virus: isolation and chemical characterization. 40 47

Disruption of Rauscher leukemia virus (RLV) with low levels of Nonidet P-40 yielded "immature" cores. These cores have a diameter of about 920 A, as opposed to the 1300-A diameter of RLV, possess knob-like protuberances, and contain a concentrically coiled internal strand apposed to the core shell. The two major polypeptide components of immature cores are (i) p30, the 30,000-dalton group-specific antigen, and (ii) a polypeptide that has the size and antigenic characteristics of P70, the 70,000-dalton precursor protein of the group-specific antigens of murine leukemia virus. Disruption of RLV at high ratios of Nonidet P-40 to virus yielded "mature" cores. These cores have an average diameter of 850 A, a smooth proteinaceous perimeter, and a collapsed internal strand, and they contain predominantly p30. Treatment of RLV with low levels of Nonidet P-40 for 16 hr at 22 degrees yielded cores that showed (I) a 70% decrease in the number of immature forms and concomitant increase in the number of mature forms, (II) a 60-90% decrease of P70, and (iii) a 30% increase in a 40,000- to 42,000-dalton protein. These results suggest that maturation of RLV cores is accomplished by cleavage of P70.
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PMID:Murine leukemia virus morphogenesis: cleavage of P70 in vitro can be accompanied by a shift from a concentrically coiled internal strand ("immature") to a collapsed ("mature") form of the virus core. 41 20

A new antitumor antibiotic, named auromomycin, was isolated from the culture broth of Streptomyces macromomyceticus, a macromomycin-producing strain. The antibiotic was recovered from the culture filtrate by salting out with ammonium sulfate and further purified by successive application of ion-exchange chromatography on Amberlite IRA-93 (Cl form) and DEAE-Sephadex (OH form), Gel filtration on Sephadex G-50 and hydrophobic chromatography on Octyl-Sepharose CL-4B. The antibiotic is an acidic polypeptide with a molecular weitht of 12,500 and an isoelectric point of pH 5.4 and consists of 16 different amino acids. It has characteristic absorption maxima at 273 nm and 357 nm in the ultraviolet spectrum and two minima at 280 nm and 350 nm in the optical rotatory dispersion spectrum. Auromomycin exhibits antibacterial activity not only against Gram-positive bacteria, but also Gram-negative bacteria. Antitumor activities of auromomycin were revealed against EHRLICH ascites carcinoma, ascites sarcoma 180, L1210 leukemia and LEWIS lung carcinoma. Auromomycin was found to be converted into macromomycin by adsorption chromatography on Amberlite XAD.
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PMID:Studies on auromomycin. 46 20

Macromomycin (MCR) is a polypeptide antimuor antibiotic isolated from the culture broth of Streptomyces macromomyceticus. Antitumor activities of MCR were examined against three different tumor system, i.e., EHRLICH ascites carcinoma, L1210 leukemia and LEWIS lung carcinoma. Daily intraperitoneal treatment with MCR for 5 days showed a strong inhibition against EHRLICH ascites carcinoma. Both single and repeated intraperitoneal injections of MCR were effective over a wide dose range against intraperitoneally inoculated L1210 leukemia and MCR intravenously administered was also active against intravenously inoculated L1210 leukemia. Daily local subcutaneous injections of MCR produced the prolongation of life span of mice to which LEWIS lung carcinoma was subcutaneously inoculated with some cured mice, but daily intraperitoneal injections of MCR showed no activity. Single intravenous administration of MCR inhibited early LEWIS lung carcinoma, but not advanced LEWIS lung carcinoma. The combination of MCR with aracytidine, or cyclophosphamide showed a synergistic activity against L1210 leukemia. MCR was not inactivated by treatment with serum, although neocarzinostatin was markedly inactivated by the same treatment.
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PMID:Biological activity of macromomycin. 46 21


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