Specific Dermatophagoides farinae extract for canine immunotherapy

Canine atopic dermatitis (cAD) is a pruritic allergic skin disease most often caused by Dermatophagoides farinae. Differences in the sensitization profile to D. farinae have been reported between people and dogs. However, allergic dogs traditionally have been treated with extracts intended for human immunotherapy.

To develop a specific allergen immunotherapy for veterinary practice enriched in canine major allergens and to demonstrate its in vitro efficacy.

Twenty privately owned dogs, clinically diagnosed with cAD, and three healthy dogs.

A veterinary D. farinae allergen extract was manufactured and characterized compared to D. farinae extract used for human immunotherapy. The protein profile was analysed by SDS-PAGE and size exclusion chromatography and Der f 15 and Der f 18 allergens quantified by mass spectrometry. The allergenic profile was studied by immunoblot and the biological potency by enzyme-linked immunosorbent assay-inhibition assays. The extract's capacity to induce cytokine production [interleukin (IL)-10, interferon (IFN)-Ɣ] by peripheral blood mononuclear cells also was evaluated.

The veterinary extract showed a higher content of high molecular weight proteins, preferentially recognized by atopic dog sera. The fold-increases in Der f 15 and Der f 18 with respect to the human extract were 2.07 ± 0.32 and 1.63 ± 0.15, respectively. The veterinary extract showed higher biological potency (0.062 versus 0.132 µg required for 50% inhibition of dogs sera) compared to the human extract and induced significantly higher levels of IL-10 (1,780 pg/mL) and IFN-Ɣ (50.4 pg/mL) with respect to the negative control.

A veterinary D. farinae extract with a higher content of dog major allergens was developed and in vitro efficacy demonstrated by immunological parameters.