title: Idiotypic network: possible explanation of seronegativity in a patient with rheumatoid arthritis.
abstract: In order to explain long term seronegativity in certain patients with rheumatoid arthritis (RA), we looked for the presence of anti-idiotypic antibodies against rheumatoid factors (RFs). From a patient's serum with classical but seronegative RA, we isolated a low quantity of the IgG fraction which partially recognized polyclonal RF idiotypes. The purified Fab'2 anti-idiotypic antibodies were able to inhibit up to 48% of in vitro RF production by pokeweed mitogen stimulated lymphocytes from a patient's peripheral blood with seropositive RA. The two main conclusions of this study are: (1) this single patient with seronegative RA has serum antibodies directed against RF idiotypes and (2) these anti-idiotypic antibodies could be implicated in the generation of seronegativity.
mesh_terms: D000328:Adult; D000368:Aged; D000918:Antibody Specificity; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D003429:Cross Reactions; D005260:Female; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D007130:Immunoglobulin Idiotypes / Q000276:immunology*; D007075:Immunoglobulin M / Q000096:biosynthesis / Q000276:immunology; D008213:Lymphocyte Activation; D008875:Middle Aged; D012217:Rheumatoid Factor / Q000096:biosynthesis / Q000276:immunology
chemical_list: D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G; D007130:Immunoglobulin Idiotypes; D007075:Immunoglobulin M; D012217:Rheumatoid Factor