Background: An immune complex transfer enzyme immunoassay for antiovalbumin immunoglobulin A (IgA) was developed.
Methods: Serum-specific antibody was reacted simultaneously with 2,4-dinitrophenyl-bovine serum albumin-ovalbumin conjugate and ovalbumin-β-D-galactosidase conjugate. The complex formed from the three components was trapped onto polystyrene balls coated with anti-2,4-dinitrophenyl group immunoglobulin G, eluted with εN-2,4-dinitrophenyl-L-lysine and transferred to polystyrene balls coated with anti-human IgA α-chain. Bound β-D-galactosidase activity was determined by fluorometry.
Results & Conclusions: The detection limit of this method for the measurement of specific anti-ovalbumin IgA was 9 fmol/tube, which was 20-fold lower than that of the enzyme-linked immunosorbent assay (ELISA). Because serum interference with this method was lower than that with the ELISA, the detection limit of this method was 300-fold lower than that by the ELISA. Anti-ovalbumin IgA was detected in 100% of healthy subjects, which was confirmed by pre-incubation with an excess amount of ovalbumin.
