Enzyme-linked immunosorbent assay of a linear, recombinant peptide designed for immunotherapy of Japanese cedar pollinosis

Introduction: Cry-consensus peptide, a recombinant T-cell epitope peptide for immunotherapy of Japanese cedar pollinosis, is a linear peptide that does not have disulfide bonds because no cysteine residue exists in the molecule. We examined whether a sandwich enzyme-linked immunosorbent assay (ELISA) could be performed for linear peptides such as Cry-consensus peptide. Methods: The 3-dimensional conformation of Cry-consensus peptide was examined by 1H NMR analysis. Nineteen monoclonal antibodies (mAbs) that recognized various domains of Cry-consensus peptide were established to use in a sandwich ELISA. The relationship between the recognition sites of mAbs and the sensitivity of the ELISA was investigated to optimize the selection of the combination of the capture and the detection antibodies. ELISA inhibitors in serum and plasma were also studied to improve the stability and the sensitivity of determination. Results: 1H NMR analysis of Cry-consensus peptide suggested that Cry-consensus peptide molecule had no portions with rigid conformation. The sensitivity of the ELISA showed a good correlation with the distance between the respective binding sites of the capture and the detection antibodies. Human serum albumin and α1-acid glycoprotein strongly inhibited the binding of the capture mAb to Cry-consensus peptide in a dose-dependent manner, and heparin also inhibited the binding in the concentration at which it is used as anticoagulant. Taken together, the findings indicated that an optimized method showed good linearity and minimal variation from 0 to 1000 ng/ml of Cry-consensus peptide. Discussion: These data indicate that this method is useful for monitoring Cry-consensus peptide concentrations in plasma or serum.