Serum Allergen-Specific Immunoglobulin E Response in Dogs With Moderate-To-Severe Leishmaniosis.

Background: Dogs with moderate-to-severe leishmaniosis develop a strong nonprotective humoral response which is mainly associated with anti-Leishmania infantum antibodies. Humoral immune response also plays an important role in canine atopic dermatitis (cAD) and is associated with allergen-specific immunoglobulin (Ig)E.

Hypothesis/objectives: To compare the serum allergen-specific IgE concentration in dogs with leishmaniosis and high levels of anti-L. infantum-specific antibodies with Leishmania seronegative clinically healthy and atopic dogs.

Materials and methods: Serum samples from 47 dogs with leishmaniosis without cAD and high anti-L. infantum antibodies were included and compared with serum from 30 atopic and 33 clinically healthy dogs. Serum samples were analysed using a commercial kit for the quantitative measurement of allergen-specific IgE. Dogs with anti-cross-reactive carbohydrate determinants (CCD)-IgE were excluded.

Results: The proportion of dogs positive for at least one allergen was significantly higher in dogs with leishmaniosis (40 of 40) than in healthy (18 of 28) and atopic dogs (10 of 30) (p < 0.001, Fisher's exact test). The median allergen-specific IgE concentration was 7.1 U/mL in leishmaniotic dogs, 4.7 U/mL in atopic dogs and 1.4 U/mL in healthy dogs. A significant difference was observed between dogs with leishmaniosis and healthy dogs (p < 0.001, Wilcoxon-Mann-Whitney U-test), while no differences were found between leishmaniotic and atopic dogs, and atopic and healthy dogs.

Conclusions and clinical relevance: Dogs with moderate-to-severe leishmaniosis and high levels of anti-L. infantum antibodies produce high levels of serum allergen-specific IgE that do not appear to be of clinical relevance. Clinicians should cautiously interpret serological allergen tests in dogs with leishmaniosis.