Characterization of the dog lipocalin allergen Can f 6: the role in cross-reactivity with cat and horse

Background Allergy to the domestic dog (Canis familiaris) affects 5–10% of the population in affluent countries. Three of four patients are allergic to more than one pet, which can only partially be explained by cross‐reactivity between serum albumins. The lipocalin protein family harbours allergens in mammalian species. Methods We set out to clone and characterize a novel dog allergen, and investigate its potential role in cross‐sensitization between dog, cat and horse. The gene encoding Can f 6 was amplified from dog skin and bladder cDNA libraries. The corresponding allergen was produced and purified by recombinant techniques and evaluated by SDS‐PAGE, size exclusion chromatography, circular dichroism spectra, ELISA and basophil activation test. Results IgE antibodies to Can f 6 were found in serum from 38% of dog‐sensitized subjects. Sequence similarities between the lipocalin allergens Can f 6, Fel d 4 (cat) and Equ c 1 (horse) suggested a probability for cross‐reactivity, which was demonstrated by competitive ELISA. The biological relevance of Can f 6 was confirmed by basophil activation test in dog‐allergic patients. Conclusion Can f 6 is a new lipocalin dog allergen that cross‐reacts with lipocalins from horse and cat. Can f 6 and homologous allergens may contribute to multisensitization and symptoms in individuals allergic to mammals.