Assessment of recombinant dog allergens Can f 1 and Can f 2 for the diagnosis of dog allergy

Summary Background The use of recombinant allergens for the diagnosis and immunotherapy of allergy may offer several advantages over allergen extracts. Objective To produce recombinant dog allergens Can f 1 and Can f 2 in Pichia pastoris yeast and to assess their suitability for the diagnosis of dog allergy. Methods Clinically diagnosed dog-allergic patients' and healthy non-atopic dog owners' reactivities against recombinant Can f 1 and Can f 2 and commercial dog epithelial extract were studied by a panel of methods including skin prick test (SPT), ELISA and IgE immunoblotting. Results Recombinant Can f 1 and Can f 2 were found immunologically functional: they bound dog-allergic patients' IgE in immunoblotting and inhibited specifically the binding of IgE to their natural counterparts in the dog allergen extract. Moreover, patients' IgE reactivity in immunoblotting to natural Can f 1 and their SPT with the recombinant allergen were perfectly concordant (φ coefficient 1.0, P<0.001). The concordance was slightly lower with recombinant Can f 2 (φ coefficient 0.92, P<0.001). A lower number of dog-allergic patients, 52%, reacted against Can f 1 than previously reported. About one-third of the patients reacted to Can f 2. In immunoblotting, the highest prevalence of reactivity, 60%, was directed to an 18 kDa component. Aminoterminal sequencing showed this to be a previously unidentified allergenic protein. Conclusions The recombinant allergens can be used reliably to identify Can f 1 and Can f 2-sensitized individuals. However, the two allergens are insufficient as reagents for diagnosing dog allergy.