title: The Ro/SSA autoantigen as an immunogen. Some anti-Ro/SSA antibody binds IgG.
abstract: The rheumatic disease autoantigen, Ro/SSA, was immunogenic to a rabbit host. The heteroimmune rabbit serum bound the Ro/SSA particle in immunoblots and in an ELISA. Both the rabbit anti-Ro/SSA and a human prototype anti-Ro/SSA serum also bound IgG; and moreover, IgG inhibited both rabbit and human anti-Ro/SSA activity. Anti-IgG activity of the rabbit and human anti-Ro/SSA sera bound Ro/SSA by Western blot and solid-phase assays. In addition, purified Ro/SSA inhibited the anti-IgG activity of the anti-Ro/SSA sera from rabbit and man. Affinity purification of the IgG- and Ro/SSA-binding fractions of the rabbit anti-Ro/SSA demonstrated that both the anti-Ro/SSA and anti-IgG activities were concentrated in these fractions. These data show that Ro/SSA and IgG share epitopes that are bound by anti-Ro/SSA antibody. Inhibition experiments suggest that this antibody is found in most human anti-Ro/SSA autoimmune sera and that the epitope(s) are found in the F(ab')2 fragment of IgG.
mesh_terms: D000818:Animals; D001324:Autoantigens / Q000276:immunology*; D002417:Cattle; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007106:Immune Sera; D005779:Immunodiffusion; D007140:Immunoglobulin Fab Fragments / Q000378:metabolism; D007074:Immunoglobulin G / Q000276:immunology*; D020733:RNA, Small Cytoplasmic; D012261:Ribonucleoproteins; D000099207:SS-A Antigen
chemical_list: D001324:Autoantigens; D007106:Immune Sera; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G; D020733:RNA, Small Cytoplasmic; D012261:Ribonucleoproteins; D000099207:SS-A Antigen; C116006:RO60 protein, human