Immunoproteomic characterization of a Dermatophagoides farinae extract used in the treatment of canine atopic dermatitis

• The commercially available D. farinae extract contains major allergens described for dogs.
• Major allergens content was 18.1 μg/mg (Der f 15) and 9.4 μg/mg (Der f 18).
• The pattern of minor allergen recognition was different compared to other studies.
• Specific IgG1 levels were higher in atopic dogs compared to healthy dogs.

BackgroundCanine atopic dermatitis is a pruritic allergic skin disease. House dust mites have been identified as the main non-seasonal responsible agent. Unlike in human allergic patients, groups 1 and 2 antigens have been described as minor allergens in dogs, while groups 15 and 18 are considered the major allergens. Despite these differences, allergic dogs have traditionally been treated using extracts intended for human immunotherapy.ObjectivesTo investigate the immunological characteristics and the allergen reactivity of dogs with atopic dermatitis using a Dermatophagoides farinae commercial extract.MethodsEighteen dogs diagnosed with atopic dermatitis and 3 healthy control dogs from the Iberian Peninsula were included in the study. All the animals were older than 12 months, from both sexes and different breeds and showed positive specific IgE against D. farinae (>2500 ELISA Absorbance Units). The D. farinae allergenic extract used in this study was manufactured and characterized. The allergenic profile of the dogs was investigated by immunoblot and specific IgE, IgG, IgG1 and IgG2 measured by direct ELISA. Allergen identity was confirmed by immunoblot inhibition and mass spectrometry analyses.ResultsThe results confirmed the relevance of groups 15 and 18 antigens, but also groups 1, 2 and other medium molecular weight allergens in the sensitization of dogs with atopic dermatitis. Immunoblot inhibition and mass spectrometry assays confirmed these results. Relevant allergens were quantified by scanning densitometry (Der f 1: 17 μg/mg, Der f 2: 20.3 μg/mg, Der f 15: 18.1 μg/mg and Der f 18: 9.4 μg/mg). Concerning immunoglobulins profile, differences in IgE and IgG1 levels were observed between non-atopic and atopic dogs.ConclusionsThe commercial D. farinae extract characterized in this study contains the major allergens involved in the sensitization of dogs with atopic dermatitis, representing a suitable candidate for its use in the diagnosis and immunotherapy of mite allergic dogs.