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 (rDf2-P).

METHODS

Eight Maltese beagle atopic dogs were sensitized to rDf2 then randomized to SCIT with rDf2-P (six dogs) or placebo (two). The immunotherapy consisted of six weekly injections of increasing doses (0.1-10.0 μg) of rDf2-P followed by four monthly injections of 10 μg of this allergen. Epicutaneous rDf2 challenges, rDf2-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 rDf2 challenge, while that of the dogs treated with rDf2-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 rDf2-specific IgE serology and immediate intradermal reactivity. Cytokine serum levels were inconclusive. There were no adverse events seen with rDf2-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.