title: Radioimmunoassay for IgG and IgM rheumatoid factors.
abstract: The present paper describes two solid phase radioimmunoassays for detecting IgG and IgM rheumatoid factors (RF). Basically, serum rheumatoid factors were bound to rabbit IgG previously adsorbed to wells of flexible microtiter plates and quantitated after the addition of 125I-Fab anti-human gamma Fd for the IgG-RF assay or 125I-IgG anti-mu chain for the IgM-RF assay. The IgG and IgM rheumatoid factor assays were tested on 56 and 30 control sera, respectively. The upper normal limits for these assays were taken for cpm test serum/cpm control pool as 1.00 (0.76 + 0.24; X + 2SD) and 1.39 (0.73 + 0.66; X + 2SD) for IgG-RF and IgM-RF, respectively. When applied to sera of patients with rheumatoid arthritis, IgM-rheumatoid factor was detected in 15 of 15 (100%) patients, and IgG-rheumatoid factor in 15 of 17 (88%). The radioimmunoassay results for both rheumatoid factors were significantly higher for these patients than for the normal control sera (P less than 0.01).
mesh_terms: D000818:Animals; D000918:Antibody Specificity; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000032:analysis; D007141:Immunoglobulin Fc Fragments / Q000032:analysis; D007074:Immunoglobulin G / Q000032:analysis*; D007075:Immunoglobulin M / Q000032:analysis*; D011817:Rabbits; D011863:Radioimmunoassay / Q000379:methods*; D012217:Rheumatoid Factor / Q000032:analysis*
chemical_list: D007140:Immunoglobulin Fab Fragments; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D012217:Rheumatoid Factor