Rheumatoid Arthritis (RA) is an autoimmune disease of unknown etiology that is characterized by chronic inflammation of the joints and by the presence, in high titers, of an autoantibody known as the rheumatoid factor (RF). The human cytomegalovirus, a member of the human Herpesviridae family, has been proposed as a potential environmental agent involved in the induction of RF production. The report of an anti-CMV antibody having structural homology to a major group of human paraproteins with RF activity, as detected by the expression of RF-associated idiotypes and by variable region sequences, provided a possible structural relationship between CMV infection and RF production. / In this thesis, the structural characterization of eight human hybridoma anti-CMV antibodies and their possible relationship to RFs is presented. All eight antibodies recognized the viral matrix phosphoprotein, known as pp65, which has previously been demonstrated to be highly immunogenic during the natural infection. Seven of these antibodies expressed a restricted number of RF-associated idiotypes. The HCV-2 anti-CMV antibody expressed the greatest number of RF-associated idiotypes and was most similar to RFs of the "PO" idiotypic family. All eight antibodies were composed of different $ rm V sb{H}/V sb{L}$ pairs, with evidence of antigen-selected somatically-induced mutations in the majority of cases. When the nucleotide sequences of these anti-CMV antibodies were compared to previously reported rearranged immunoglobulin sequences, the majority were found to share the highest degree of identity with antibodies possessing RF activity. This data provides evidence that there is extensive overlap between the autoimmune and anti-pathogen antibody repertoires. / Comparisons of the anti-CMV antibodies with homologous RF sequences revealed that most of the amino acid differences could be accounted for by putative somatic mutation events and different junctional diversity in the third complementarity determining region (CDR3) of the antibody heavy chains. This was supported by the cloning and sequencing of the variable regions of a human hybridoma RF, known as C304, which was derived from a patient with active RA. The C304 heavy and light chain sequences had high identity with one of the anti-pp65 antibodies (HCV-3) and with a previously reported antibody directed against the human herpes simplex virus (HSV). The sequences diverged at points of suspected somatic mutations and, extensively, in the CDR3 of the heavy chains. / Although no evidence was obtained that could definitively implicate human herpes viruses in the induction of RFs, this work has provided an analysis of the relationship between idiotype expression and antigenic specificity. This data has enabled the identification of the sequence differences between RFs and anti-viral antibodies that potentially play a role in determining antigenic specificity and provides the basis for an experimental model to address the issue of how primary amino acid sequence determines the specificity of human antibodies.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.41756 |
| Date | January 1994 |
| Creators | Rioux, John David |
| Contributors | Newkirk, M. M. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Division of Experimental Medicine.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001397703, proquestno: NN94707, Theses scanned by UMI/ProQuest. |
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