Molecular analysis of ligand binding requisites for human B lymphocyte activation and tolerance through membrane immunoglobulin-M.
Item
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Title
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Molecular analysis of ligand binding requisites for human B lymphocyte activation and tolerance through membrane immunoglobulin-M.
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Identifier
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AAI8820897
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identifier
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8820897
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Creator
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Rudich, Steven M.
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Contributor
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Adviser: Patricia K. A. Mongini
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Date
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1988
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Language
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English
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Publisher
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City University of New York.
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Subject
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Health Sciences, Immunology
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Abstract
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The ligand binding requisites necessary to initiate membrane lgM-mediated human B lymphocyte clonal expansion and tolerance were investigated with a well-characterized set of soluble murine monoclonal anti-human antibodies. The anti-lgM monoclonal antibody requisites studied included the affinity and binding stoichiometry for membrane lgM in addition to the {dollar}\mu{dollar} chain domain specificity. Anti-lgM antibody affinity and binding stoichiometry were measured by equilibrium-binding studies and Scatchard plot analysis with several membrane lgM-positive B cell lines. Specificity for C{dollar}\mu\sb1{dollar}, C{dollar}\mu\sb2{dollar}, and C{dollar}\mu\sb4{dollar} lgM domains was indicated by competition radioimmunoassays with enzymatically-derived {dollar}\mu{dollar} chain domain fragments as well as mutant lgM myeloma proteins which lacked heavy chain domains.;Diversity in ability to induce B lymphocyte DNA synthesis in splenic B cell populations was observed among the ligands which could not be attributed to inhibitory Fc-mediated signaling. Although mitogenic antibodies were identified with each domain specificity, C{dollar}\mu\sb1{dollar}-specific antibodies were as a whole, the least effective stimulators. The T cell-dependent mitogenic capability of the monoclonal antibodies was found to be largely a direct linear function of their affinities for B cell membrane lgM. The notable exception to this was in the case of the C{dollar}\mu\sb1{dollar}-specific monoclonal antibodies which bound monogamously to membrane lgM. Mixtures of both mitogenic and non-mitogenic antibodies were found to induce marked synergy for DNA synthesis. T cell factor-independent B cell DNA synthesis was observed for certain mixtures of monoclonal antibodies which included a unique C{dollar}\mu\sb4{dollar}-directed antibody. This was interpreted as indicating that supra-optimal cross-linking of membrane lgM molecules on the B cell surface can obviate the requirement for growth factor signaling.;Ligand binding requirements for B lymphocyte tolerance were studied in several novel B cell malignant clonal populations which were found to be exquisitely sensitive to anti-lgM-mediated inhibition of DNA synthesis. The affinity threshold for inducing tolerance was found to be significantly less than that observed for inducing B cell clonal expansion. This, as well as other observations, indicated that the anti-lgM antibody binding requisites for tolerance induction in these B cell leukemias are much less stringent than the requisites for inducing proliferation.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
