IDENTIFICATION OF THE DISEASE-RELATED T-CELL EPITOPE OF OVALBUMIN AND EPITOPE-TARGETED T-CELL INACTIVATION IN EGG ALLERGY

An ovalbumin (OVA)-specific T cell line (TCL) was established from a patient with hen egg allergy. The TCL was CD4+, expressed alpha beta T cell receptor, and recognized OVA presented by HLA-DR10. Based on the response of the TCL to synthetic OVA peptides, it was found that the TCL recognized OVA 323-339, which is a major T cell epitope presented by murine I-A(d). The TCL secreted high levels of IL-5, but undetectable amounts of IL-2, interferon-gamma, and IL-4 when stimulated with OVA or the OVA 323-339 peptide. Since IL-5 is an important growth and chemotactic factor for eosinophils, it is possible that these OVA 323-339-specific T cells can contribute to human egg allergy. To our knowledge, this is the first demonstration of food allergen-specific TCL establishment and identification of a T cell epitope possibly I-elated to the allergic reaction to food antigens. An analog peptide of the OVA 323-339 which is known to strongly bind to I-A(d) partially inhibited the response of the TCL to OVA 323-339 presented by HLA-DR10, raising the possibility of peptide-based immunotherapy of food allergy.