Quantitation of bovine immunoglobulin G2 by a competitive fluorescence immunoassay

Bovine immunoglobulin G2 (IgG2) was quantitated by fluoroimmunoassay (FIA) based on competition with fluorescein-conjugated IgG2 for Sepharose-bound anti-IgG2 antibodies. The optimal range was 0.1 to 1 microgram IgG2. The FIA was compared with the single radial immunodiffusion (SRD) test. Both methods gave comparable means and standard errors for IgG2 in serum. The FIA method was 30 times more sensitive.