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Query: UMLS:C0079731 (B-cell lymphoma)
 16,671 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The beta 2-adrenergic transmembrane signal transduction was investigated in malignant B-cells from 15 patients with low grade non-Hodgkin's lymphoma as compared with normal lymphocytes of seven healthy adults. The number of beta 2-adrenoceptors and the response of adenylate cyclase (AC) to isoproterenol were slightly decreased in lymphoma cells. The responsiveness of AC to forskolin was 8-fold lower in lymphoma cells, whereas the response to cholera toxin showed no difference. These findings demonstrate an impairment of the beta 2-adrenergic signal transduction in low grade lymphoma cells that particularly affects the function of AC. The comparison with forskolin resistant mutants of an adrenocortical tumor cell line, Y1 (Schimmer et al., J Biol Chem 262: 15521-15526, 1987), suggests that the availability of functional active alpha subunits of stimulatory G proteins (Gs) might be reduced in human B-cell lymphoma, although other mechanisms known to inhibit the AC activity might be involved.
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PMID:Reduced responsiveness of adenylate cyclase to forskolin in human lymphoma cells. 165 84

The murine B cell lymphoma CH12.LX, which bears cell surface IgM specific for the phosphatidyl choline epitope of sheep red blood cells, is capable of spontaneous isotype switching in vitro. Switching to IgG3, IgG1, IgG2b, and IgA has been observed and variants expressing those isotypes have been isolated and cloned. We have developed a procedure for precise numerical evaluation of the frequency of switching to the several isotypes to which CH12.LX can switch. We have used a modified Poisson method which can distinguish between treatments which change isotype switch frequency and those which affect, in an isotype-specific fashion, growth or secretion rates of cells which have already switched. In this report we examine the effect of several cytokines, cholera toxin, hydroxyurea, and antigen on the isotype switch frequency of CH12.LX. The strongest effect observed was that of transforming growth factor-beta, which increases switch frequency 40-fold to an absolute switch frequency of 0.04 switch events (from IgM to IgA expression) per cell division. Interleukin-4 (IL-4) and cholera toxin also increase the switch frequency of CH12.LX while IL-5, IL-6 (with or without antigen), antigen (SRBC) alone, interferon-gamma, or hydroxyurea have no effect. We have shown that none of the cytokines studied change the relative frequency of switching to the available isotypes, only the absolute frequency of switching. We infer from this that the factors tested do not 'instruct' CH12.LX to switch to a particular isotype, but rather they deliver a 'go' signal to cells committed to switching to IgA at high frequency, rarely to IgG3, IgG1, or IgG2b, and never to IgG2a or IgE.
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PMID:Ig isotype switching in B lymphocytes. The effect of T cell-derived interleukins, cytokines, cholera toxin, and antigen on isotype switch frequency of a cloned B cell lymphoma. 204 38

Rat liver beta-galactoside alpha-2,6-sialyltransferase and Vibrio cholerae sialidase were used with cytidine-5'-monophospho-N-acetyl-[3H]neuraminic acid (CMP-[3H]NeuAc) to specifically probe the distribution and sialylation state of Gal beta 1-4GlcNAc residues on N-linked saccharides on the surfaces of murine lymphocytes. The relative extent of exogenous sialyltransferase-mediated sialylation (per cellular protein) was thymocytes greater than T-cells greater than T-cell lymphoma (EL-4) greater than B-cells greater than B-cell lymphoma (AKTB-1b) greater than splenocytes. Prior desialylation increased exogenous resialylation by 23.8-, 13.1-, 7.1-, 7.9-, 7.0-, and 5.3-fold for splenocytes, B-cells, T-cells, EL-4, AKTB-1b, and thymocytes, respectively. Though numerous glycoproteins were labeled, the majority of the Gal beta 1-4GlcNAc residues were detected on a relatively small number of cell surface proteins, many of which are well-defined lymphocyte antigens. Gal beta 1-4GlcNAc residues on thymocytes were found to exist in an undersialylated state on T200 but not on other antigens (e.g., Thy-1). T200 was found to be fully sialylated on mature cells (i.e., hydrocortisone-resistant thymocytes and splenic T-cells), suggesting that its sialylation state is developmentally regulated. These studies indicate that the number, sialylation state, and polypeptide distribution of the penultimate structure, Gal beta 1-4GlcNAc, differ on N-linked saccharides on the surfaces of different lymphocyte populations.
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PMID:Surfaces of murine lymphocyte subsets differ in sialylation states and antigen distribution of a major N-linked penultimate saccharide structure. 213 33

We have observed that a 2-h pretreatment of murine B cells with cholera toxin (CT) renders the B cell incapable of receiving an activation signal via surface Ig as measured by cell volume increase and entry into the S phase of the cell cycle. In contrast, CT pretreatment does not inhibit the delivery of a signal by IL-4, as measured by increase in cell volume. In fact, CT pretreated B cells are able to respond to anti-Ig in the presence of IL-4, as measured by both an increase in cell size and entry into S suggesting that IL-4 overcomes the effects of CT on normal B cell activation. Despite blocking the anti-Ig-mediated entry into the cell cycle, CT was not able to interfere with the induction of nonresponsiveness by anti-Ig in normal B cells or with the delivery of growth-inhibitory signal to the B cell lymphoma WEHI-231. These results suggest that there are two signaling pathways mediated by cross-linking of surface Ig: one pathway sensitive and the other insensitive to modulation by CT.
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PMID:Cholera toxin-sensitive and insensitive signaling via surface Ig. 278 8

The Ia+ B cell lymphoma, AKTB-1b, fails to stimulate thymic lymphocytes in a one-way mixed lymphocyte reaction unless pretreated with sialidase or inhibitors of N-linked oligosaccharide processing. A comparison of different sialidases and sialyltransferases suggests that the removal of only a subset of total surface sialic acid, rather than net desialylation of the cell surface, is required. Three sialidases were compared, including Vibrio cholerae (VC) and Clostridium perfringens (CP), which will cleave alpha 2-3, alpha 2-6, and alpha 2-8, sialic acid linkages, and Newcastle Disease virus (NDV), which will remove only alpha 2-3 and alpha 2-8 linked sialic acid. When treated with equivalent units of sialidase, CP-, VC-, and NDV-treated cells were 24-fold, sixfold, and threefold better stimulators than untreated cells. In contrast, VC released 1.3-fold and 2.5-fold more sialic acid per cell than did CP or NDV, respectively. Furthermore, VC was superior in reducing the levels of binding of the sialic acid-specific lectin, Limulus polyphemus agglutinin, in exposing Gal beta 1-3GalNAc and Gal beta 1-4GlcNAc residues, and in desialylating gangliosides. Two-dimensional gel analysis indicated that VC and CP were both equal and superior to NDV in the desialylation of iodinatable cell-surface proteins, including H-2Kk, I-A beta k, and a highly sialylated 65,000 dalton protein of unknown identity. Maximal resialylation of CP-treated cells with exogenously added CMP-NANA and either the alpha 2-3(Gal beta 1-3GalNAc) or alpha 2-6(Gal beta 1-4GlcNAc) sialyltransferase did not reduce the stimulatory capacity of these cells. However, resialylation of VC-treated cells with just CMP-NANA alone resulted in 49% reversal of their stimulatory capacity, and no additional reversal could be achieved with either of the sialyltransferases. Although the alpha 2-6(Gal beta 1-4GlcNAc) sialyltransferase was capable of adding back approximately 10% of the sialic acid removed, the endogenous activity added back approximately 0.1% of the total sialic acid removed. SDS-PAGE gels of the sialylated cells indicated that the exogenously added sialyltransferase labeled many different proteins, whereas the endogenous activity labeled far fewer proteins, predominantly in 46,000 and 25,000 m.w. range. Both the desialylation and resialylation data suggest that the sialidase-dependent stimulation is due to the desialylation of specific membrane structures. Together with previous studies, these data suggest that the sialic acids involved are probably alpha 2-6 linked to N-linked glycosyl moieties.
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PMID:Cell surface sialic acid influences tumor cell recognition in the mixed lymphocyte reaction. 295 14

The presence of Helicobacter pylori in the gastroduodenal mucosae is associated with chronic active gastritis, peptic ulcers and gastric cancers such as adenocarcinoma and low-grade gastric B-cell lymphoma. In response to the presence of antibiotic-resistant strains, the use of vaccines to combat this infection has become an attractive alternative. The present study used a murine model of infection by a mouse-adapted H. pylori strain to determine whether infection in BALB/c mice can be successfully eradicated by intragastric vaccination with H. pylori heparan sulphate-binding proteins (HSBP) covalently coupled to the beta-subunit of cholera toxin (CTB). It was shown that vaccination confers protection against exposure of BALB/c mice to the pathogen, as revealed by microbiological, histopathological and molecular methods.
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PMID:Protection of BALB/c mice against experimental Helicobacter pylori infection by oral immunisation with H pylori heparan sulphate-binding proteins coupled to cholera toxin beta-subunit. 1084 7

Cell surface sialylation and beta1-6 branching of L-PHA reactive oligosaccharides play an important role in metastatic capacities of various tumor cell lines. We analyzed the expression and sialylation of L-PHA reactive oligosaccharides in human diffuse large B cell lymphoma (DLBCL). DLBCL was grouped into three types; i). Group A, non-reactive type with no expression of L-PHA reactive oligosaccharides, ii). Group B, sialylated type with expression of sialylated L-PHA reactive oligosaccharides and iii). Group C, non-sialylated type with expression of non-sialylated L-PHA reactive oligosaccharides. To clarify the linkage of sialic acid residues in L-PHA reactive oligosaccharides of Group B cases, L-PHA lectin histochemistry after treatment with two different neuraminidases was performed. In all Group B cases, L-PHA binding reactivity was found after treatment with Vibrio cholerae neuraminidase. But not after treatment with Newcastle disease virus neuraminidase. These data indicate that alpha2,6-linked sialic acid residues were predominantly involved in sialylation of L-PHA reactive oligosaccharides of Group B. To clarify the relationship between expression of N-acetylglucosaminyltransferase V (GnT-V), which catalyzes beta1-6 branching of L-PHA reactive oligosaccharides, and L-PHA reactivities in DLBCL, we investigated the expression of GnT-V using immunohistochemical methods. Most of the Group B and C cases expressed GnT-V while 33% of Group A cases showed no expression of GnT-V. These data suggest that expression of GnT-V is not always correlated with the expression of L-PHA reactive glycoconjugates. Furthermore, survival of patients in Group A which showed no expression of GnT-V was significantly shorter than that of patients in Group C which expressed GnT-V. Therefore, loss of non-sialylated L-PHA reactive oligosaccharides due to lack of expression of GnT-V in lymphoma cells may be associated with aggressiveness of DLBCL.
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PMID:Alpha-2,6-sialylation of L-PHA reactive oligosaccharides and expression of N-acetylglucosaminyltransferase V in human diffuse large B cell lymphoma. 1453 92

Sphingolipid metabolites are important regulators of cell growth and apoptosis. To clarify the biological roles of cell surface sialylation in the effects of sphingomyelinase (SM) treatment on cell viability, the human diffuse large B cell lymphoma cell line, HBL-2 with or without treatment with Vibrio cholerae neuraminidase, was incubated with exogenous bacterial SM which is a key enzyme of ceramide production from sphingolipids in cell membranes. SM treatment enhanced viability of HBL-2 cells compared to non-treatment after 6 h of incubation. On the other hand, viability of HBL-2 cells was decreased by SM treatment with neuraminidase pre-treatment after 6 and 24 h of incubation, and ceramide production on cell surfaces of SM treated cells was enhanced by neuraminidase treatment as shown by flow cytometric analysis. Furthermore, treatment with D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol, an inhibitor which specifically reduces the activity of UDP-glucose:ceramide glucosyltransferase in combination with SM treatment, causes the viability of HBL-2 cells to be decreased more with neuraminidase pre-treatment than without it. Exogenous C6-ceramide induced HBL-2 cell death, and there was no difference in the effects of C6-ceramide after 6 h of incubation between treatment and non-treatment with neuraminidase. Together these data suggest that alteration in susceptibility of HBL-2 cells to SM by neuraminidase treatment may precede the process of ceramide production, and that cell death through the activation of SM, which induces ceramide production, is regulated by cell surface sialylation in DLBCL.
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PMID:Regulatory roles of cell surface sialylation in susceptibility to sphingomyelinase in human diffuse large B cell lymphoma. 1594 62

Surface sialylation and glycosylation of tumor cells is known to affect various biological phenomena. In the present study, we analyzed the regulatory roles of cell surface sialylation in cell adhesion to galectin-1 in the human diffuse large B cell lymphoma (DLBCL) cell line, HBL-2, and Burkitt's lymphoma cell line, HBL-8. Vibrio cholerae neuraminidase treatment enhanced HBL-2 cell adhesion to galectin-1, suggesting that sialic acid inhibits HBL-2 cell adhesion to galectin-1. The data from employing two different neuraminidases, Vibrio cholerae and Newcastle disease virus neuraminidase, showed that alpha2,6-linked sialic acid plays an important role in the inhibition of HBL-2 cell adhesion to galectin-1. In addition, neuraminidase treatment enhanced the cell adhesion to galectin-1 much more with the highly sialylated HBL-8 3G3 clone than with the hyposialylated HBL-8 3D2 clone. Flow cytometric analysis revealed the expression of partially sialylated L-PHA reactive oligosaccharides on the surfaces of HBL-2 cells. Swainsonine (SW) treatment also enhanced HBL-2 cell adhesion to galectin-1. These data indicate that SW treatment decreased sialylated L-PHA reactive oligosaccharides resulting in cell surface desialylation and leading to enhancement of cell adhesion to galectin-1. In conclusion, alteration of cell surface sialylation or N-glycan expression regulates cell adhesion to galectin-1 in human malignant lymphoma.
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PMID:The regulatory roles of cell surface sialylation and N-glycans in human B cell lymphoma cell adhesion to galectin-1. 1632 92