Hornet venom allergen antigen 5, Dol m 5: Its T-cell epitopes in mice and its antigenic cross-reactivity with a mammalian testis protein

Background: A major venom allergen of white-faced hornet (Dolichovespula maculata) is antigen 5, Dol m 5. It is a 204-residue protein having 23% to 35% sequence identity with several proteins from diverse sources. The biologic function of antigen 5 and its sequence-related proteins is not known. Objective: This study mas dune to delineate the T-cell epitopes of Dol m 5 and to test their cross-reactivity with a sequence-related mouse testis protein, tpx. Methods: T-cell epitope mapping and cross-reactivity were studied with 15- or 20-residue peptides bf their stimulation of spleen cells from mice immunized with recombinant Dol m 5 or tpx fragments. Results: Three of 20 peptides studied were found to represent major T-cell epitopes of Dol m 5, being recognized by five or all of six mouse strains tested. One major epitope peptide. residue 176-195, showed cross-reactivity in BALB/c mice with the homologous antigen 5s from yellow jackets and wasps, as well as with mouse tpx. The cross reactivity of Dol m 5 and mouse tpx is not reciprocal because spleen cells from tpx-immunized mice mere stimulated by the hornet peptide, but cells from Dol m S-immunized mice mere not stimulated by the corresponding tpx peptides. Conclusion: Cross-reactivity of vespid antigen 5 and mouse tps mag be of importance in insect allergy because human and mouse testis proteins are highly homologous.