Identification of cross‐reactive allergens between the $Dermatophagoides$ $farinae$ house dust mite and the $Toxocara$ $canis$ nematode in dogs with suspected allergies

Background: Immunoglobulin (Ig)E cross‐reactivity has been shown between Dermatophagoides farinae (Df; house dust mite) and the nematode Toxocara canis (Tc), yet its allergen basis is unknown.ObjectivesTo identify the Df allergens IgE‐cross‐reactive with those of Tc. Animals: Archived sera from 73 dogs with suspected allergy sensitised to Df. Materials and Methods: We performed a combination of Pet Allergy Xplorer (PAX) and enzyme‐linked immunosorbent assay (ELISA) inhibitions with excretory–secretory and somatic (i.e. nematode body) extracts of Tc or recombinant Tc tropomyosin on coats of Df, Der f 15 and Zen‐1 (ELISA) or PAX allergens.ResultsThe ELISA and PAX inhibitions established that there is mutual yet variable cross‐reactivity between the Tc excretory–secretory extract, purified Der f 15 and purified Zen‐1. This cross‐reactivity is likely to involve cross‐reactive glycans, as there is no inhibition between the Tc excretory–secretory extract and recombinant Der f 15 without its predicted natural O‐glycans. We also confirmed a heterogeneous cross‐reactivity between the somatic Tc extract and Der p 11 (paramyosin), as well as between the recombinant Toxo c 3 and Der p 10 tropomyosins. The cross‐reactivity among tropomyosins and paramyosins is likely to involve peptidic epitopes, as these recombinant allergens are not glycosylated. Conclusions and Clinical Relevance: In dogs with suspected allergies, the cross‐reactivity between Tc and Df for dogs is complex and heterogeneous. Some of the cross‐reactive IgE recognises shared glycans on Der f 15 and Zen‐1, while some targets peptidic epitopes on shared paramyosins and tropomyosins. We do not exclude that additional cross‐reactive allergens between Df and Tc also might exist.