Degranulation of basophilic leukemia cells on branched-chain peptide array with an OVA–DNP double epitope

• The degranulation assay system using a spot-synthesized peptide array was developed.
• Using lysine side chains, the double epitope branched-chain peptide was synthesized.
• This model incorporates epitope heterogeneity and induced degranulation on array.

Simple method for identification of heterovalent allergen epitopes was constructed to reflect the allergic reaction initiated by the cross-linking of the IgE receptors. The peptide array-based degranulation assay that enables interaction between solid support-bound peptide pairs and IgE sensitized basophilic leukemia cells was developed. Using lysine side chains, a chicken egg white ovalbumin (OVA) epitope and a dinitrophenol (DNP) modified amino acid was synthesized in the branched-chain peptide array. The basophilic leukemia cells sensitized with anti-OVA IgE and anti-DNP IgE induced degranulation directly on the branched-chain peptide array. The OVA–DNP double peptide disk caused the release of 37.5% of β-hexosaminidase whereas the DNP-only peptide disk caused the release by 20.9%. These results show that the double epitope branched-chain peptide array can induce degranulation, and would represent a suitable model for screening the heterovalent epitope pairs of allergens.

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