Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026764 (multiple myeloma)
 36,148 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To evaluate subclass specificity and aggregate size requirements of IgG receptors on mouse cells, we measured binding of radiolabeled monomeric and BDB-aggregated mouse myeloma proteins fractionated into various sizes by means of gel filtration. Monomers, tetramers, and high molecular weight (approximately 10(7) daltons) aggregates were used. The various cells and cell lines studied could be segregated into three patterns of reactivity: (a) Macrophage and macrophage-like cell lines bound monomer IgG2a preferentially; high molecular weight IgG aggregates bound as follows: IgG1 = IgG2b = IgG2a. (b) Lymphoid lines D2N and S49 showed no capacity to bind monomer IgG2a; high molecular weight aggregates bound as follows: IgG1 = IgG2b less than IgG2a. (c) Other Thy-1-positive lymphoid cell lines (EL4 and L5178) and normal T and B cells showed no capacity to bind monomer IgG; high molecular weight IgG aggregates bound to a lesser extent than to cells of the first two categories in the following manner: IgG1 less than IgG2b greater than or equal to IgG2a. The variable pattern of reactivity of the macrophage-like cell lines with monomer and aggregated IgG suggested that two distinct receptors for IgG were present: one capable of binding IgG2a and another capable of binding all aggregates. Further evidence for this hypothesis was obtained by analysis of the inhibitory capacity of different IgG subclasses on the binding of aggregated IgG and monomer IgG2a to P388 cells. Inhibition of monomer IgG2a binding was effected only by monomer or aggregated IgG2a, whereas inhibition of binding of aggregated IgG1 or IgG2b was noted with aggregates of all three subclasses with some preferential inhibition by monomer IgG2b being observed. Furthermore, monomer IgG2b binding was preferentially inhibitable by monomer IgG2b. It is postulated from these data that two receptor sites are present on this macrophage-like cell line, one reactive with aggregates of all three subclasses as well as monomer IgG2b, and another receptor specific for monomer IgG2a which also binds aggregated IgG2a. Support of this concept was obtained by trypsinization experiments in which the binding of monomer IgG2a was markedly decreased by trypsin treatment of cells, whereas the binding of aggregated IgG2b was unaffected by this treatment.
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PMID:Receptors for IgG: subclass specificity of receptors on different mouse cell types and the definition of two distinct receptors on a macrophage cell line. 30 Jul 83

Human myeloma proteins of the four IgG subclasses and their Fc, F(ab)2, and Fab fragments were tested for their ability to inhibit antibody-dependent human K lymphocyte-mediated cytotoxicity to chicken erythrocytes (CRBC) sensitized with specific rabbit antibodies. In addition, the adsorption of K cells onto glass bead columns coated with myeloma proteins was investigated. Myeloma proteins and their Fc fragments of all four subclasses inhibited K cell activity. However, there were wide variations within a given subclass and IgG2 and IgG4 proteins usually inhibited less than IgG1 and IgG3 proteins. Aggregation of the weakly inhibitory proteins with bis-diazotized benzidine increased their inhibitory effect. An IgG1 half-molecule with a deletion in the Cgamma3 domain was weakly inhibitory. Passage of lymphocytes through glass bead columns coated with IgG1 and IgG3 proteins removed K cell activity. In contrast, columns coated with IgG2 and IgG4 proteins, even when aggregated with BDB, failed to absorb K cells but removed significant numbers of SIg positive B lymphocytes. An enhancement of the antibody-dependent cytotoxicity was observed in 34% of the inhibition experiments in the presence of low concentrations of the weakly inhibitory proteins, usually IgG2 and IgG4. This enhancement occurred more frequently (53% of the experiments) with Fc fragments independent of the subclass. Moreover, addition of IgG2 and IgG4 but not IgG1 and IgC3 fragments induced a dose-dependent cytotoxicity to CRBC in the absence of anti-CRBC antibodies. These data indicate that IgG2 and IgG4 proteins have a lower affinity to K cells than IgG1 and IgG3 proteins and are compatible with an earlier hypothesis that proposes that more than one site on the Fc fragment can react with Fc receptors. The present results suggest in addition that there may be functionally different sites, one having a triggering function in K lymphocyte lysis that may be localized on the second constant domain and one being responsible for high affinity binding of IgG to cell receptors that is probably localized on the third constant domain.
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PMID:Interaction of K lymphocytes with myeloma proteins of different IgG subclasses. 100 86

An autoradiographic binding assay employing (125)I-labeled heat-aggregated mouse IgG2b myeloma protein (MOPC 141) was used to demonstrate receptors for IgG on 20-45% of Balb/c thymocytes and on 70-80% of splenocytes. Binding could also be shown with heat or BDB aggregates of another IgG2b (MOPC 195), with IgG1 and with human gamma-globulin, but not with aggregated chicken gamma-globulin, IgA, BSA, nor with aggregated Fab fragments of IgG2b. Optimum binding was obtained at 37 degrees C. Detection of binding was dependent upon aggregate size with complexes of more than 100 IgG molecules being optimal, aggregates of 6-25 detecting splenocytes but not thymocytes, and aggregates of less than 6 binding to a negligible extent. Comparison of grain counts on various cell types showed mastocytoma cells (P815) and macrophages averaging 40-50 grains/cell/day, allogeneically activated thymocytes 20-30, splenocytes 2-3, L5178 lymphoma cells 1, and positive thymocytes 0.6 grains/cell/day. Double labeling experiments for surface Ig, theta-antigen, and agg IgG receptor on mouse spleen cells indicated that a relatively high density of receptor was present on about 80% of B cells, 30% of T cells, and 60% of SIg(-), theta(-), null cells.
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PMID:Receptors for aggregated IgG on mouse lymphocytes: their presence on thymocytes, thymus-derived, and bone marrow-derived lymphocytes. 413 93