Use of antagonist peptides to inhibit in vitro T cell responses to Par j1, the major allergen of Parietaria judaica pollen

Par j 1.0101 is one of the two major allergens of the Parietaria judaica (Pj) pollen and its three-dimensional structure was built by 3D structural homology modelling. The resultant model was used to identify putative IgE binding regions. Western blot analysis of gene fragmentation products showed that the 1-30 region was capable of binding specific IgE from a pool of sera (n=30) of patients allergic to Parietaria judaica pollen. Using the structural model as a guide, deletion and site directed mutagenesis of the 1-30 region was performed and the amino acids involved in IgE binding identified. In addition, a synthetic peptide covering the 1-30 region was also capable of binding human IgE without triggering histamine release from basophils of Pj allergic patients (n=6) and thus represents an haptenic molecule with potential use as an immunotolerant agent. This epitope is also present on the Par j 2.0101 major allergen representing a common IgE epitope. It is also an immuno-dominant epitope since it was capable of inhibiting 30% of all the specific IgE against the Parietaria judaica major allergens and therefore it might be a candidate for the future development of immunotherapeutics.