title: Natural anti-immunoglobulin autoantibodies: irrelevant by-products or immunoregulatory molecules?
abstract: Anti-immunoglobulin autoantibodies (anti-Ig auto-Abs), particularly IgM-anti-IgG (classical rheumatoid factor), have been studied mainly in the context of rheumatoid arthritis. In this article we focus on other members of the anti-Ig family, including the natural IgG-anti-F(ab')2 auto-Ab, and look for clinical and experimental findings supporting a role of these antibodies in the regulation of the immune response. We discuss the evidence for suppression of auto- and alloreactive B cells by IgG-anti-F(ab')2 auto-Ab and the role of this Ab in the pathogenesis of certain diseases, such as autoimmune hemolytic anemia. The structure of the antibody's antigen-binding site was clarified by isolating the VL and VH gene segments from the cDNA of B cells. Sequence analyses revealed germline gene identity of VL chains and 88% homology with the closest germline gene of VH chains. Finally, we discuss hypothetical models concerning the immunoregulatory role of natural anti-Ig auto-Abs.
authors.affiliation: Institute of Immunology, Department of Transplantation Immunology, University of Heidelberg, Germany. peter_terness@krzmail.krz.uni-heidelberg.de
authors.forename: P
authors.initials: P
authors.lastname: Terness
authors.forename: G
authors.initials: G
authors.lastname: Opelz
mesh_terms: D000276:Adjuvants, Immunologic; D000818:Animals; D000918:Antibody Specificity / Q000276:immunology*; D001323:Autoantibodies / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000276:immunology*; D007074:Immunoglobulin G / Q000276:immunology*; D007136:Immunoglobulins / Q000276:immunology*
chemical_list: D000276:Adjuvants, Immunologic; D001323:Autoantibodies; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G; D007136:Immunoglobulins