The invention relates to a novel horse allergen consisting of a heterodimeric protein having a first peptide chain and a second peptide chain together having an overall sequence identity of at least 70% with the combined sequences of SEQ ID NO:3 and SEQ ID NO: 4, as well as a single chain protein having an overall sequence identity of at least 70%, such as 75%, 80%, 85%, 90%, 95%, or 98%, with the combined amino acid sequences according to SEQ ID NO: 3 and SEQ ID NO: 4. The invention further relates to the use of the protein in methods of diagnosis and therapy of Type I allergy, and kits and compositions for use in such methods.
