A two-site sandwich radioimmunoassay of beta 2-microglobulin with monoclonal antibodies.
Among 21 batches of monoclonal antibodies raised against beta 2-microglobulin (anti-beta 2m), 6 reacted with soluble beta 2m, as well as with beta 2m present in association with HLA heavy chains on the surface of leukocytes. The remaining 15 anti-beta 2m antibodies bound with soluble beta 2m, but failed to react with beta 2m on the cell surface. No monoclonal anti-beta 2m antibodies revealed precipitin lines when they were tested against beta 2m in immunodiffusion. When 2 anti-beta 2m antibodies with different specificities were mixed together, however, they developed a precipitin line against beta 2m. Based on these observations, there was only 1 epitope on beta 2m that was available for the binding with a monoclonal anti-beta 2m antibody with either specificity. This allowed the development of a solid-phase radioimmunoassay in which beta 2m in test specimens was sandwiched between immobilized anti-beta 2m of 1 specificity and radiolabeled anti-beta 2m of a heterologous specificity in a single step. Monoclonal antibodies with at least 2 different specificities would be required for developing a sandwich-type immunoassay of polypeptides, such as beta 2m, that do not display 2 or more epitopes of the same specificity.
D000818:Animals; D000911:Antibodies, Monoclonal / Q000032:analysis; D000939:Epitopes; D005921:Glomerulonephritis / Q000276:immunology; D006801:Humans; D005779:Immunodiffusion; D007962:Leukocytes / Q000276:immunology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D011863:Radioimmunoassay / Q000379:methods*; D001613:beta 2-Microglobulin / Q000032:analysis* / Q000276:immunology / Q000652:urine
D000911:Antibodies, Monoclonal; D000939:Epitopes; D001613:beta 2-Microglobulin