Immune Complex Transfer Enzyme Immunoassay for Anti-Thyroglobulin IgG Using 2,4-Dinitrophenyl-thyroglobulin, Biotinyl-thyroglobulin and Streptavidin-β-D-galactosidase Conjugate

Abstract A sensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) for anti-thyroglobulin IgG in serum is described. Anti-thyroglobulin IgG in serum was reacted simultaneously with 2,4-dinitrophenyl-thyroglobulin and biotinyl-thyroglobulin. The immune complex formed of the three components was trapped onto polystyrene balls coated with (anti-2,4-dinitrophenyl group) IgG and, after washing, reacted with streptavidin-β-D-galactosidase conjugate. After washing, the immune complex was eluted from the polystyrene balls with eN-2,4-dinitrophenyl-L-lysine and transferred to polystyrene balls coated with (anti-human IgG γ-chain) IgG. β-D-Galactosidase activity bound to the last polystyrene balls was assayed by fluorometry. Biotinylthyroglobulin and streptavidin-β-D-galactosidase conjugate could be prepared more easily than thyroglobulin-β-D-galactosidase conjugate used in the previous immunoassay. Inactive β-D-galactosidase, used to eliminate interference by anti-β-D-galactosidase antibodies in ...