title: Anti-idiotypic antibodies prevent the serologic detection of antiribosomal P autoantibodies in healthy adults.
abstract: A subset of SLE patients has serologically detectable autoantibodies to the ribosomal P proteins (anti-P). We reported the discovery of covert anti-P antibodies and their masking IgG-inhibitory antibodies in the sera of healthy adults. The aim of this study was to determine if these IgG-inhibitory antibodies are anti-idiotypic antibodies (anti-Ids). IgG and IgG-depleted fractions of plasma from two healthy adults were assayed for inhibition of anti-P F(ab')2 binding to the ribosomal P proteins in immunoblot. Anti-P antibody activity was completely inhibited by plasma IgG, whereas there was no inhibition by IgG-depleted plasma. IgG-inhibitory antibodies recognized a cross-reactive epitope among anti-P from different SLE patients. Plasma IgG from one healthy adult was depleted of pepsin agglutinators and generic anti-F(ab')2 antibodies by adsorption with an affinity column prepared with normal IgG F(ab')2. Unretained IgG bound exclusively to anti-P F(ab')2 in ELISA. Using four affinity columns, we isolated IgG anti-Ids to anti-P antibodies from four healthy adults. These purified anti-Ids bound to anti-P F(ab')2 from a healthy adult and SLE patients. They did not bind to F(ab')2 fragments prepared from normal IgG or anti-dsDNA. Ribosomal antigens blocked this anti-Id-Id interaction. Purified anti-Ids inhibited the binding of anti-P F(ab')2 from patients to ribosomal P proteins. SLE patients without overt anti-P antibodies also possessed IgG anti-Ids to anti-P antibodies. We conclude that IgG-inhibitory antibodies are anti-Ids to anti-P antibodies, and are directed to public idiotopes on anti-P antibodies. These anti-Ids may be part of an Id network that regulates anti-P antibody expression, and perhaps pathogenicity.
authors.affiliation: Arthritis and Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.
authors.forename: Z J
authors.initials: ZJ
authors.lastname: Pan
authors.forename: C J
authors.initials: CJ
authors.lastname: Anderson
authors.forename: H A
authors.initials: HA
authors.lastname: Stafford
mesh_terms: D000328:Adult; D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology*; D001323:Autoantibodies / Q000097:blood*; D003429:Cross Reactions; D000939:Epitopes; D006801:Humans; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G / Q000276:immunology*; D008180:Lupus Erythematosus, Systemic / Q000276:immunology; D015800:Protozoan Proteins; D011817:Rabbits; D012269:Ribosomal Proteins / Q000276:immunology*
chemical_list: D000888:Antibodies, Anti-Idiotypic; D001323:Autoantibodies; D000939:Epitopes; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G; C064601:L12E protein, Trypanosoma cruzi; D015800:Protozoan Proteins; D012269:Ribosomal Proteins