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

An ovalbumin (OVA)-specific T cell line (TCL) was established from a p atient 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 T CL recognized OVA 323-339, which is a major T cell epitope presented b y murine I-A(d). The TCL secreted high levels of IL-5, but undetectabl e 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 che motactic factor for eosinophils, it is possible that these OVA 323-339 -specific T cells can contribute to human egg allergy. To our knowledg e, this is the first demonstration of food allergen-specific TCL estab lishment and identification of a T cell epitope possibly I-elated to t he allergic reaction to food antigens. An analog peptide of the OVA 32 3-339 which is known to strongly bind to I-A(d) partially inhibited th e response of the TCL to OVA 323-339 presented by HLA-DR10, raising th e possibility of peptide-based immunotherapy of food allergy.