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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Since it has been proposed that T cells with receptors for the Fc portion of IgE (T epsilon) in rats, mice and humans are IgE-specific regulatory cells, it was investigated whether mice with an IgE-secreting hybridoma might be a source of large numbers of T epsilon cells. BALB/c mice with ascitic tumors of the IgE hybridoma B53 (epsilon, kappa, anti-DNP) developed high serum concns of monoclonal IgE which was followed by the appearance of large numbers of Lyt1-2+ L3T4- T epsilon cells. In contrast, mice bearing a non-IgE producing variant of B53 failed to develop T epsilon cells. Mice infused with cell-free ascites fluid (containing high levels of monoclonal IgE) from the IgE-secreting B53 hybridoma developed high serum IgE levels and also developed high numbers of T epsilon cells. Mice infused with cell-free ascites obtained from the non-IgE-secreting variant ENP-1 (containing very low amounts of IgE) did not develop either high serum IgE levels or T epsilon cells. These findings suggest that high serum IgE concns induce large numbers of T cells that express phenotypic markers of suppressor cells and have surface IgE-Fc receptors. These studies extend to IgE the principle that hybridomas and plasmacytomas induce large numbers of immunoregulatory T cells that express Fc receptors specific for the heavy chain class of the secreted monoclonal immunoglobulin. Since T epsilon cells are normally present only in small numbers, their marked increase in mice with IgE-secreting hybridomas identifies a ready source of large numbers of T epsilon cells that can be used to investigate their regulatory properties.
Mol Immunol 1986 Nov
PMID:Increased T epsilon cells in BALB/c mice with an IgE-secreting hybridoma. 295 Mar 16

The binding sites of rat IgE to mast cell receptor were investigated by the use of proteolytic fragments and a monoclonal antibody to epsilon chain (MARE-1). Three main fragments were characterized by short-time papain digestion of IgE: F(ab')2-E, a fragment related to the C, 4 domain, and an asymmetric fragment corresponding probably to an IgE molecule with one proteolyzed C, 3 domain. Neither F(ab')2-E nor C, 4 could interfere with the binding of IgE to rat mast cells. These two fragments did not show significant polymerization upon heating at 56 degrees C, while large amounts of polymers were produced from whole IgE, MARE-1 monoclonal antibody was found to react neither with F(ab')2 nor with C, 4, thereby suggesting its interaction with the C, 3 domain. MARE-1 was found to inhibit partially (about 55%) the binding of IgE to its receptor. Taken together the results indicate that the binding sites of IgE to rat mast cell receptor are located within the C, 3 domain. In addition, isolation of the C, 4 domain will be useful to evaluate its participation in the affinity of IgE to receptors of other cells such as lymphocytes or macrophages.
Mol Immunol 1987 Feb
PMID:Studies of the IgE binding sites to rat mast cell receptor with proteolytic fragments and with a monoclonal antibody directed against epsilon heavy chain: evidence that the combining sites are located in the C epsilon 3 domain. 295 98

Rat basophilic leukemia (RBL) cells carry two surface glycoprotein molecules named R (or alpha) and H which, when detergent solubilized, bind to rat IgE-Sepharose. The same two molecules also bind to rat IgG-Sepharose but with a lower affinity. R is a component of the high affinity Fc receptor for IgE. In the present study the inhibition of the binding of R and H to rat IgG-Sepharose by various homologous and heterologous immunoglobulins was used to assess their relative affinities for the two receptor molecules. Ranking the rat immunoglobulins in order of their affinities for the R receptor yielded: IgE much greater than IgG2a greater than IgG1 greater than IgG2b; and for H: IgE greater than IgG2b greater than IgG1 greater than IgG2a. Rat IgG2c inhibited the binding of both R and H but a precise ranking could not be assigned. Conclusive evidence has been obtained for the Fc specificity of these interactions. The affinities of the mouse IgG subclass/R interactions can be ranked: IgG1 greater than IgG2a greater than IgG2b; and for the H receptor: IgG1 greater than IgG2b greater than IgG2a. All of the mouse proteins and other heterologous IgGs, such as those of sheep, goat, equine and rabbit origin, interacted considerably more strongly with H than with R. No interaction with mouse IgG3 could be detected under the conditions tested.
Mol Immunol 1988 Jul
PMID:The interaction of IgG subclasses with solubilized Fc receptors of rat basophilic leukemia cells. 297 Nov 36

The receptor with high affinity for IgE consists of a tetrameric complex of polypeptides, one of which (alpha), contains the binding site for IgE. The function of the other chains--a single beta and two disulfide-linked gamma chains--is unknown. We report the cloning of a murine hybridoma that secretes an IgG1 antibody which specifically reacts with the beta subunit. Studies with this monoclonal antibody show that the subunit stoichiometry of the receptor is unaffected by the presence or absence of bound IgE. We also found that under certain conditions where the alpha beta gamma 2 complex dissociates, beta remains attached to the dimer of gamma chains, indicating that these chains contact each other in the native receptor. In rat basophilic leukemia cells--a neoplastic line of mucosal-type mast cells--all of the beta subunits expressed by the cells appeared to be associated with the high affinity receptor. However, in at least one cell line which has no high affinity receptors--a putative rat lymphoma line--beta or beta-like polypeptides were also expressed.
Mol Immunol 1988 Jul
PMID:Studies with a monoclonal antibody to the beta subunit of the receptor with high affinity for immunoglobulin E. 297 Nov 37

The role of IgE antibodies in the initiation of allergen induced release of mediators from sensitised mast cells is discussed; both from the point of view of their binding to the high affinity Fc(epsilon)RI receptor and in their provision of a triggering signal, resultant upon the cross-linking of cell bound IgE molecules by specific antigen (allergen). A possible inter-relationship between the Fc(epsilon)RI and a low affinity receptor for the IgG4 isotype on human mast cells is considered, in the light of evidence that the two types of receptor could be acting synergistically in certain clinical allergy situations (e.g. atopic eczema). It is suggested that a similar juxta-positioning of Fc(gamma 4)RII and Fc(epsilon)RI receptors on human B-lymphocytes might provide scope for regulation of IgE synthesis by IgG4 auto-antibodies directed against this immunoglobulin isotype.
Mol Immunol 1988 Nov
PMID:Inter-receptor relationships in effector cell triggering, with particular reference to the mast cell. 297 63

Lymphoid tumors are productive experimental models for the study of lymphocyte immunoglobulin receptors. Investigations with Fc receptor expressing lymphoid tumor cells have generated much useful information about: (a) the developmental expression of the different classes of Fc receptors on lymphoid cells of the T- and B-lineages; (b) the biochemical steps involved in the regulation of Fc receptor expression on lymphoid cells; (c) the structures of lymphoid cell Fc receptors and their genes; (d) the signals that induce alterations in the expression of Fc receptors on lymphoid cells; and (e) the molecular specificity of the binding of immunoglobulin to lymphoid cells Fc receptors. In addition, tumors that secrete immunoglobulins are providing useful models for analysis of the mechanisms by which B-cells influence Fc receptor expression and function on T-cells. An interesting, bi-directional immunoregulatory circuit involving Fc epsilon R+ host T-cells and IgE-secreting hybridoma cells has been identified that could prove useful in the analysis of the regulation of epsilon heavy chain expression. The studies discussed in this article and elsewhere in this volume serve to emphasize that, in addition to being clonal sources of key molecules such as Fc receptors and their messenger RNAs, lymphoid tumor cells that express Fc receptors are powerful and unique experimental models for investigating the developmental biology, regulation and function of lymphocyte Fc receptors.
Mol Immunol 1988 Nov
PMID:Immunoglobulin (Fc) receptors on murine T- and B-lymphocytes: investigations using tumor models. 306 31

Since secretion of IgE antibodies is known to be blocked by tunicamycin, the first aim of the present study was to determine at which step of glycosylation or processing secretion was restored. For this purpose, murine hybridoma cells secreting an anti beta-lactoglobulin IgE were incubated either in the presence of inhibitors of glucosidase I (castanospermine or N-methyl-1-deoxynojirimycin), or of an inhibitor of Golgi mannosidase II (swainsonine). Terminal galactoses predominate on the native IgE N-linked carbohydrate chains. The action of the trimming inhibitors, which results in changes in these terminal galactose residues, was monitored through detecting binding modifications to Concanavalin A and to the lectin of Ricinus communis. The antibody activity was also evaluated by a radioimmunoassay. It was shown that neither secretion nor anti beta-lactoglobulin activity of the IgE antibody are modified in the presence of any of the trimming inhibitors, whereas secretion is blocked in the presence of tunicamycin. Other biological activities of this IgE were investigated: no difference was observed in the binding of the carbohydrate-modified IgE molecules to normal mouse mast cells, nor to RBL-1 cells, as demonstrated by passive cutaneous anaphylaxis and in vitro binding tests respectively. However, traces of unglycosylated epsilon chain (mol. wt 61,000) found in tunicamycin treated cell supernatant did not bind to RBL-1 cell Fc epsilon receptors. These findings globally suggest that secretion occurs only if the tetradecasaccharide precursor of N-linked carbohydrate chains is transferred from its lipid-carrier to the polypeptide. Further, the presence of such non-processed oligosaccharides (Glc3Man9GlcNAc2) on IgE, does not seem to modify any of the biological activities of this molecule.
Mol Immunol 1987 Aug
PMID:Effect of trimming inhibitors on the secretion and biological activity of a murine IgE monoclonal antibody. 311 10

Previous studies have established that sensitivity (IgE antibody response) to Ra5S, a 5000 mol. wt protein of short ragweed pollen, is significantly associated with host possession of HLA-DR2. The same allele was implicated [Goodfriend et al. (1985) Molec. Immun. 22, 899-906] in sensitivity to Ra5G, a 4400 mol. wt homologue of Ra5S in giant ragweed pollen, based on frequency of co-sensitivity to both proteins. However, data reported here generated in HLA-DR assays of mono-sensitive individuals demonstrate that sensitivity to Ra5S and Ra5G is associated with separate alleles: DR2 and DRw52 respectively. Results consistent with the same sensitivity/DR associations were obtained in immunoabsorption studies with sera from co-sensitive individuals. As HLA-DR2 and DRw52 have identical alpha but different beta chain types (beta 1 and beta 3), it was considered that IgE antibody responses to Ra5S and Ra5G are associated with distinct DR-beta genes.
Mol Immunol 1987 Nov
PMID:Specific IgE antibody responses to ragweed allergens Ra5S and Ra5G associated with distinct HLA-DR beta genes. 312 29

Jackfruit lectin, jacalin, prepared from two batches of jackfruit seeds showed a different specificity in precipitating reaction in Agarose gel with various purified immunoglobulins and secretory components. Jacalin-P, extracted from jackfruit seeds from the Philippines, reacts only with serum IgA and secretory IgA of IgA1 subclass. Jacalin-O, extracted from jackfruit seeds from Okinawa prefecture in Japan, makes a strong precipitin are with IgA1 subclass and a weak precipitin arc with IgA2 subclass of IgA2m(2) allotype, IgM, IgD and IgE. Human secretory IgA of IgA1 subclass was isolated from human milk by a single jacalin-P affinity chromatography using D-galactose as a dissociating agent. From conventionally purified human secretory IgA preparation, secretory IgA of IgA1 subclass and of IgA2 subclass were separated from each other. The former was separated as jacalin-P adsorbed fraction and the latter as jacalin-P non-adsorbed fraction by the affinity chromatography. Subclass composition of secretory IgA in human milk was determined by the affinity column and was calculated to be 70% for IgA1 and 30% for IgA2 subclass. Jacalin affinity chromatography has several advantages compared with antibody coupled affinity chromatography, notably, high capacity, inexpensiveness, and very mild extraction of IgA1 subclass.
Mol Immunol 1987 Nov
PMID:A simple procedure for the isolation of human secretory IgA of IgA1 and IgA2 subclass by a jackfruit lectin, jacalin, affinity chromatography. 312 30

The control of production of the membrane (m) vs secreted (s) forms of immunoglobulin heavy chains was investigated in a panel of cell lines expressing different heavy chain classes but identical light chains (lambda) and variable regions. These cell lines could be induced towards Ig secretion by mitogen treatment. During this process a shift from m to s heavy chain production takes place. Here we show that, similarly to IgA- and IgE-producing B cells, in IgG2a-producing I.29 cells the gamma m-gamma s shift was accompanied by a shift in the corresponding mRNAs, with a decrease of gamma m mRNA and an increase of the gamma s mRNA in LPS-stimulated cells. By contrast, the micron mRNA was increased in LPS-stimulated IgM-producing cells, albeit these cells synthesized reduced amounts of micron polypeptides. The utilization of the translational level in the early steps of B lymphocyte maturation thus distinguishes the mode of regulation of mu chains from those of the other isotypes. In addition, in B cells a post-translational event blocks the secretion of IgM but not of IgG or IgE.
Mol Immunol 1988 Feb
PMID:The control of membrane and secreted heavy chain biosynthesis varies in different immunoglobulin isotypes produced by a monoclonal B cell lymphoma. 313 67


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