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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The close relation between rat mast cells and rat basophilic leukemia (RBL) cells with regard to the presence of receptors for IgE and Fc gamma led us to generate monoclonal antibodies directed against cell surface antigens. Hybridomas were obtained by the fusion of NS1 mouse myeloma cells with murine spleen and lymph node cells. The culture supernatants were assayed by two ELISA techniques: a) for the production of mouse immunoglobulin in general and b) for antibodies directed against surface antigens of RBL cells. For this purpose RBL cells were attached to polyvinyl chloride microtitre plates. Eight hybrids produced antibodies directed against surface antigens on RBL cells. Hybrids were cloned and characterized with regard to their isotype and light chains. All eight clones secreted IgM with K light chains. Immunofluorescence studies performed with RBL cells revealed that all eight antibodies were able to show a specific fluorescence. Furthermore, four of these eight antibodies also showed a specific fluorescence with purified rat mast cells. These four antibodies were analyzed as to their ability of interacting with the IgE-receptor on RBL cells and purified rat mast cells. They reduced the binding rate of radiolabelled rat IgE to RBL and rat mast cells. A mutual inhibition of the passive cutaneous anaphylaxis (PCA) reaction in the rat by either mixing mouse reaginic serum directed against 2,4-dinitrophenol bovine serum albumin (DNP-BSA) or by mixing monoclonal mouse anti-DNP IgE with the monoclonal mouse anti-cell surface (rat basophilic leukemia, rat mast cell) IgM was determined.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Interaction of monoclonal antibodies with the IgE-receptor on rat mast cells and rat basophilic leukemia (RBL) cells. 242 99

We constructed a recombinant gene encoding an immunoglobulin (Ig) heavy chain consisting of the variable region from the phosphorylcholine (PC)-specific secreting myeloma MOPC167 and the epsilon constant region from SJL mice. This gene, cloned into the shuttle vector pSV2gpt, was transfected into J558L myeloma cells, and stable transformants that expressed the epsilon gene were cloned. The IgE heavy chain in these transformants is associated with the endogenous lambda light chain and is secreted as an intact IgE molecule. However, the secreted IgE does not bind to PC conjugated to bovine serum albumin (PC-BSA). The MOPC167 kappa chain gene was cloned into the shuttle vector pSV2neo and was transfected into the epsilon heavy-chain transformant. Stable transformants were cloned that expressed both the epsilon heavy chain and the kappa light chain. IgE secreted from such a transformant was shown to bind to PC-BSA. Both types of secreted recombinant IgE bound to rat basophilic leukemia (RBL) cells, but only the IgE produced by the cell line transformed with the MOPC167 kappa gene could be cross-linked with PC-BSA to cause serotonin release.
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PMID:Expression of a recombinant murine IgE in transfected myeloma cells. 243 Oct 59

We have studied the ability of human B- and T-lymphoblastoid cell lines, as well as of peripheral lymphoid cells from leukemia patients, to take up alpha-fetoprotein (AFP) and other serum proteins. Two technical approaches have been employed, both using fluorescent protein derivatives (FITC-proteins): microscopic examination of labelled cells using epifluorescent illumination and quantitation of endocytosed proteins by fluorescence-activated cell sorting (FACS). Compared to human resting T-lymphocytes, all T- and B-cell lines tested exhibited positive staining for fluoresceinated AFP and transferrin (Tf) and a significant increase, up to 100-fold, of the number of AFP and Tf molecules endocytosed per cell. Labelling was prevented or strongly diminished by a 100-fold excess of unlabelled protein. Preliminary results with peripheral lymphoid cells harvested from leukemia patients showed the presence of AFP- and Tf-positive cells in the blood of all patients examined. Intensity of labelling was related to the type of leukemia cells and/or the degree of cell maturation. Most cell lines exhibited positive staining for alpha 2-macroglobulin (alpha 2M) and also, to a lesser extent, for serum Vitamin D3 binding protein (DBP). In contrast, no labelling was observed with FITC-serum albumin (FITC-Alb) or FITC-ovalbumin (FITC-OVA). Comparative uptake of several FITC-proteins by a single cell population revealed significant quantitative and qualitative differences.
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PMID:Specific uptake of alpha-fetoprotein by malignant human lymphoid cells. 244 4

Electrochemical detection of the rat basophilic leukemia (RBL-1) cells has been carried out by applying cyclic voltammetry. The detection system consists of a basal plane pyrolytic graphite electrode and a porous nitrocellulose membrane filter to trap RBL-1 cells. When the potential of the graphite electrode was run in the range of 0-1.0 V vs SCE, RBL-1 cells gave peak currents at 0.34 V vs SCE as well as 0.65 V vs SCE. There is a linear relationship between the peak current at 0.34 V vs SCE and the cell numbers of RBL-1. In the range of (0.4-2.0) X 10(5) cells. The peak current of RBL-1 cells was attributed to serotonin. When dinitrophenylated bovine serum albumin (DNP-BSA) as a model allergen was added to RBL-1 cells sensitized with anti-DNP IgE, the peak current decreased because of the degranulation of RBL-1 cells leading to serotonin release. On the other hand, RBL-1 cells sensitized with anti-DNP IgE did not respond to egg white, pollens, house dust, and milk.
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PMID:Detection of rat basophilic leukemia by cyclic voltammetry for monitoring allergic reaction. 247

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

At the entry into mitosis, cells abruptly lose membrane activities such as phagocytosis, pinocytosis, and capping. The present studies test if mitotic cells also resist functional responses to cell surface ligand-receptor interactions. The IgE receptors of RBL-2H3 rat basophilic leukemia cells were labeled with anti-dinitrophenol IgE (anti-DNP-IgE) and then cross-linked with multivalent ligands (DNP-bovine serum albumin [BSA]; DNP-B-phycoerythrin; DNP-BSA-gold). IgE-receptor cross-linking modulates cell surface organization and function and releases serotonin and other mediators of allergic and asthmatic reactions from interphase cells (Pfeiffer, J. R., JC. Seagrave, B. H. Davis, G. G. Deanin, and J. M. Oliver, 1985, J. Cell Biol., 101:2145-2155). It was found that anti-DNP-IgE-receptor complexes are preserved on the cell surface throughout mitosis; they continue to bind DNP-proteins, and the resulting antigen-IgE-receptor complexes can redistribute to coated pits on the cell surface. Furthermore, there is no loss of [3H]serotonin through mitosis. Nevertheless, antigen-stimulated [3H]-serotonin release is strongly impaired in mitotic-enriched as compared with mixed interphase or G1-enriched cell populations. In addition, antigen binding transforms the surface of interphase cells from a microvillous to a plicated topography and stimulates the uptake of fluorescein isothiocyanate-conjugated dextran by fluid pinocytosis. Mitotic cells maintain a microvillous surface topography after antigen treatment, and fluid pinocytosis virtually ceases from prometaphase to telophase. Phorbol myristate acetate, a tumor promoter that activates protein kinase C, restores surface ruffling activity to mitotic cells. Thus, the mitosis-specific freezing of membrane and secretory responses is most likely due to the failure of transmembrane signaling.
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PMID:Surface functions during mitosis in rat basophilic leukemia cells. 293 15

In the present study, a simple solid-phase radioimmunoassay was developed to determine detergent-extracted human leukemia-associated cell membrane antigens. In the assay, 96-well microtiter plates are coated with human leukemia cell membrane antigens containing a T cell leukemia or a non-T cell leukemia antigen in the presence of a detergent, and treated with 1.6% bovine serum albumin solution. The coated antigens were reacted with an appropriate murine monoclonal antibody (mAb), i.e., SN2 or SN3, which defines a T leukemia antigen or a non-T leukemia antigen, respectively. The bound mAb is determined by a second reaction with 125I-labeled F(ab')2 of goat anti-mouse Ig. The effect of the following detergents on the assay was investigated: Nonidet P-40 (NP-40), Renex 30, deoxycholate, 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate (CHAPS) and taurocholate. The best antigen dose-dependent antibody binding results were obtained using the plates coated with antigens in the presence of taurocholate, a rarely used detergent, whereas no significant antibody binding was observed in the assays using 2 nonionic detergents, i.e., NP-40 and Renex 30. In addition, the usefulness of the present assay with taurocholate during the purification of the antigens was demonstrated. It is very likely that the present solid-phase radioimmunoassay using taurocholate will also be useful in determining other non-leukemia cell membrane antigens.
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PMID:Simple solid-phase radioimmunoassay for human leukemia-associated cell membrane antigens. 299 85

L-Asparaginase (ASNase), a drug widely used in the treatment of acute lymphoblastic leukemia, has been reported to decrease serum T4-binding globulin (TBG) levels, while results of serum albumin determinations were conflicting. This effect in vivo has been attributed to depressed liver protein synthesis, but this hypothesis has not been proved. To investigate this problem, human hepatoma (Hep G2) cells were continuously labeled for 4 h with 100 microCi/ml [35S]methionine in the absence or presence of graded amounts of ASNase (from 0.1 nM to 0.1 mM). Media and cell lysates were collected, immunoprecipitated with antialbumin or anti-TBG serum and protein A, and submitted to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Gels were sliced, and the radioactivity was counted in a beta-counter. A dose-dependent inhibition of TBG and albumin biosynthesis (as well as of total protein synthesis) was demonstrable, but TBG appeared to be more sensitive to the action of the drug. In fact, TBG biosynthesis was reduced by 8% with 0.1 nM ASNase, while an effect on albumin was observed only at 1 nM ASNase; 50% inhibition was obtained with 30 nM ASNase in the case of TBG and with 800 nM in the case of albumin. At the highest concentration (0.1 mM), TBG biosynthesis was reduced by 94%, and albumin biosynthesis by 75%. ASNase also proved to have a time-dependent effect, as assessed by the measurement of radioimmunoassayable TBG in the media from Hep G2 cells grown in the presence of 10 nM ASNase for 1-4 days. The TBG concentration was progressively reduced, by 40% after 1 day to 85% after 4 days. In pulse-chase experiments, a reduction of total (intracellular plus secreted) immunoprecipitable TBG and, to a lesser extent, albumin was observed, suggesting that the drug also affected the catabolism of newly synthesized proteins. These results provide the first in vitro evidence that ASNase actually inhibits TBG biosynthesis. This effect is not specific for TBG, but this protein appears to be more susceptible than albumin to ASNase action. This can explain why in patients treated with ASNase for leukemia, a decrease in serum TBG concentrations has not always been associated with a reduction in serum albumin levels.
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PMID:Effect of the antileukemic agent L-asparaginase on thyroxine-binding globulin and albumin synthesis in cultured human hepatoma (HEP G2) cells. 301 70

A human erythroleukemia cell line, K-562 T1, was adapted to a protein-free chemically defined medium; that is, the medium does not contain any proteins such as exogenous hormones, growth factors, serum and serum albumin. The K-562 T1 cells which can proliferate in a protein-free medium are one of the model systems suitably supporting the autocrine hypothesis, which claims that cancer cells produce and respond to their own growth factors. The K-562 T1 cells were cultured in a protein-free medium at large scale and the growth factors were purified from the conditioned medium. It was found that K-562 T1 cells produce at least two growth factors; one is LGF-I (leukemia-derived growth factor-I) which can stimulate the proliferation of a wide range of human leukemia cell lines and the other is LGF-II (leukemia-derived growth factor-II), which can contribute to the growth of fibroblasts. LGF-I was purified using QAE-Sephadex, Bio Gel P-60 and Mono S FPLC. The purified protein was found to be homogenous by SDS-polyacrylamide gel electrophoresis and NH2-terminal sequence analysis. The molecular weight of LGF-I was 20,000 by SDS-polyacrylamide gel electrophoresis. The 30 NH2-terminal residues of LGF-I are the same as that of ubiquitin. Ubiquitin is a protein found in eukaryotic cells with molecular weight of 8,600. In the nucleus ubiquitin is conjugated to histone 2A to form the nuclear protein A24 which may play a role in regulation of chromatin structure, and in the cytoplasm is part of an ATP-dependent non-lysosomal proteolytic pathway. However, its physiological significance has not yet been fully resolved. Ubiquitin purified from bovine thymus did not show cell proliferating activity for any cells tested. The results suggest that LGF-I is a new autocrine growth factor with a molecular weight of 20,000 daltons, containing ubiquitin at the NH2-terminal end.
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PMID:N-terminal amino acid sequence of leukemia derived growth factor (LGF) from human erythroleukemia cell culture. 303 91

We have re-examined, by high pressure liquid chromatographic (HPLC) procedures, the hydrolysis of 3H-labeled inositol phospholipids in rat basophilic leukemia (RBL-2H3) cells. Previous studies showed no clear correlation between the release of any particular inositol metabolite and the calcium signal in these cells. Paradoxically no responses were observed when the cells were stimulated with the antigen, aggregated ovalbumin, in the absence of external Ca2+. We report here that in the absence of external Ca2+ aggregation of the IgE receptor by agents other than aggregated ovalbumin causes the release of small amounts of [3H]inositol phosphates and a small increase in levels of cytosol Ca2+ (approximately 25 nM). The response, however, varied with the type of stimulant used. Within seconds after addition of 24 mol of dinitrophenol conjugated with 1 mol of bovine serum albumin to cells primed with dinitrophenol-specific IgE there was a small burst in release of [3H]inositol 1,4,5-triphosphate, [3H]inositol 1,3,4,5-tetrakisphosphate, and [3H]inositol 1,3,4-trisphosphate which was followed by a gradual rise in inositol 1,3,4-trisphosphate, inositol bisphosphate, and inositol monophosphate. Eventually, all inositol phosphates reached different steady state levels which were maintained for at least 40 min. In contrast, the initial response to oligomeric IgE, which aggregates receptors at a relatively slow rate, was muted although the subsequent development of the response was the same. The levels of inositol pentakisphosphate and hexakisphosphate remained unchanged. These and other studies with cell extracts support the conclusion that inositol 1,4,5-trisphosphate, a putative messenger for release of intracellular Ca2+, was converted to inositol 1,3,4,5-tetrakisphosphate and thence to inositol 1,3,4-trisphosphate. Both trisphosphate metabolites were dephosphorylated in sequential fashion by phosphatase enzymes in the cytosolic and membrane fractions. However, the appearance of several isomers of inositol monophosphates and bisphosphates suggested that degradation proceeded through multiple pathways in the intact cell.
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PMID:The kinetics of phosphoinositide hydrolysis in rat basophilic leukemia (RBL-2H3) cells varies with the type of IgE receptor cross-linking agent used. 304 Jul 3


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