Proof of concept of the preventive efficacy of high‐dose recombinant mono‐allergen immunotherapy in atopic dogs sensitized to the Dermatophagoides farinae allergen Der f 2

Background Allergen immunotherapy is currently the only intervention proposed to specifically prevent clinical flares after allergen challenges. The low molecular weight Der f 2 (Df2) is a major allergen in Japanese dogs sensitized to Dermatophagoides farinae house dust mites. Objectives Pilot, blinded, placebo‐controlled experiment testing the efficacy of subcutaneous immunotherapy ( SCIT ) with high doses of recombinant Df2 conjugated to the maltotriose pullulan (r D f2‐P). Methods Eight Maltese beagle atopic dogs were sensitized to r D f2 then randomized to SCIT with r D f2‐P (six dogs) or placebo (two). The immunotherapy consisted of six weekly injections of increasing doses (0.1–10.0 μg) of r D f2‐P followed by four monthly injections of 10 μg of this allergen. Epicutaneous r D f2 challenges, r D f2‐specific IgE serology and intradermal reactivity, as well as serum cytokine level measurements, were performed throughout the study. Results Subcutaneous injections of placebo did not alter the cutaneous reactivity after r D f2 challenge, while that of the dogs treated with r D f2‐P SCIT disappeared in five of six dogs (83%) and was reduced in one of six (17%). During SCIT maintenance, skin lesion scores were significantly lower in dogs receiving SCIT compared to those treated with placebo. This clinical improvement was accompanied by a concurrent, yet not significant, decrease in r D f2‐specific IgE serology and immediate intradermal reactivity. Cytokine serum levels were inconclusive. There were no adverse events seen with r D f2‐P SCIT. Conclusions and clinical importance The new mono‐allergen SCIT appears safe and effective for reducing skin lesions after allergen challenges; it deserves further testing in dogs with spontaneous atopic dermatitis.