title: Immunological origin and functional properties of catalytic autoantibodies to amyloid beta peptide.
abstract: OBJECTIVE
  Objectives The objectives of this study are to (1) evaluate the ability of the immune system to synthesize specific antibodies that catalyze the degradation of amyloid beta peptide (Abeta) and to (2) evaluate the prospect of developing a catalytic IVIG (CIVIG) formulation for therapy of Alzheimer's disease (AD).
  
  
  CONCLUSIONS
  Polyclonal autoantibodies from humans without dementia hydrolyzed Abeta specifically. The catalytic activity improved as a function of age. Patients with AD produced catalytic antibodies at increased levels. IgM-class antibodies expressed the activity at levels superior to IgGs. Production of catalytic autoantibodies appears to be an innate immunity function with adaptive improvements occurring upon Abeta overexpression, which suggests a beneficial function of the catalytic activity. The catalytic autoantibodies impeded Abeta aggregation, dissolved preformed Abeta aggregates, and inhibited Abeta cytotoxicity in tissue culture. Recombinant catalytic antibodies from a human library have been identified, validating the phenomenon of antibody-catalyzed Abeta cleavage. As a single catalyst molecule inactivates multiple Abeta molecules, catalytic antibodies may clear Abeta efficiently. IVIG did not cleave Abeta, indicating the importance of purification procedures that maintain catalytic site integrity. Traditional Abeta-binding antibodies form immune complexes that can induce inflammatory reaction and vascular dysfunction. Catalysts do not form stable immune complexes, minimizing these risks. Criteria appropriate for developing a CIVIG formulation with potential therapeutic utility are discussed, including isolation of the Abeta-specific catalytic subsets present in IgM and IgG from human blood.
authors.affiliation: Department of Pathology and Laboratory Medicine, Chemical Immunology Research Center, University of Texas-Houston Medical School, Houston, TX 77030, USA. Sudhir.Paul@uth.tmc.edu
authors.forename: Sudhir
authors.initials: S
authors.lastname: Paul
authors.forename: Stephanie
authors.initials: S
authors.lastname: Planque
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Nishiyama
mesh_terms: D000544:Alzheimer Disease / Q000276:immunology / Q000628:therapy; D016229:Amyloid beta-Peptides / Q000276:immunology*; D017151:Antibodies, Catalytic / Q000276:immunology*; D001323:Autoantibodies / Q000276:immunology*; D001324:Autoantigens / Q000276:immunology*; D006801:Humans; D006868:Hydrolysis; D007113:Immunity, Innate; D007074:Immunoglobulin G / Q000276:immunology; D007075:Immunoglobulin M / Q000276:immunology; D016756:Immunoglobulins, Intravenous / Q000276:immunology / Q000627:therapeutic use; D018448:Models, Immunological; D010446:Peptide Fragments / Q000032:analysis
chemical_list: D016229:Amyloid beta-Peptides; D017151:Antibodies, Catalytic; D001323:Autoantibodies; D001324:Autoantigens; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D016756:Immunoglobulins, Intravenous; D010446:Peptide Fragments
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