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Immune complex transfer enzyme immunoassay for anti-ovalbumin IgA in serum
Kouichi Hirota1, Tomomi Kamashima, Seiichi Hashida
1Division of Maternal and Child Health Science, National Institute of Health and Nutrition, 1-23-1 Toyama, Shinjuku, Tokyo 162-8636, Japan. khirota@nih.go.jp
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-beta-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 epsilonN-2,4-dinitrophenyl-L-lysine and transferred to polystyrene balls coated with anti-human IgA alpha-chain. Bound beta-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.