A prevalent exposure to male dog is a risk factor for exclusive allergic sensitization to Can f 5: An Italian multicenter study

Dog allergens are a common cause of allergic sensitization and respiratory symptoms worldwide, particularly in geographical areas characterized by a high level of pet ownership. The aim of our study was to evaluate if mono sensitization to Can f 5, as well as high levels of anti-Can f 5 IgE is associated to a prevalent exposure to male dog in an Italian population. Fourteen Allergy Units, distributed over the Italian territory ("Italian Allergic Respiratory Diseases Task Force") participated in this cross-sectional study. Each centre examined retrospectively all the CRD results saved in their databases from 1st January 1 2013 to 31 December 2018. Only patients with monosensitization to Can f 5 were selected and analyzed, regardless of the presence of IgE against other inhalant allergens. All selected Can f 5-monosensitized patients were contacted by e-mail or phone for information on their clinical symptoms at the time of blood sampling, on the modality of exposure to dogs according to our previously published criteria. Of 751 selected patients 627 (83.5 %), 247 males and 380 females, with an age range of 6-90 years, responded to the email or accepted the telephone interview, and provided the requested information. In the case of children, information was obtained from their parents. All patients suffered from respiratory allergy (rhinitis and/or asthma), and symptoms associated to food allergy, if present, were also recorded. In the group with low anti-Can f 5 IgE (n=230), NDC (n=44), MDC (n=46) and FDC (n=140) accounted for 19%, 20%, and 61% respectively. In the group with medium levels of IgE (n=346), NDC (n=23), MDC (n=242), and FDC (n=81) accounted for 7%, 70%, and 23%, respectively. Finally, in the group with high anti-Can f5 IgE (n=51), NDC (n=1), MDC (n=44), and FDC (n=6) accounted for 25%, 86%, and 12%, respectively. The titre of anti-Can f 5 IgE, according to the prevalent exposure to dogs, is significantly higher in MDC (2.5, 1.3-6.8, median, lower and upper quartiles) than in NDC (0.7, 0.4-1.6), and in FCD (0.7, 0.4-0.1), respectively (p<0.001, Kruskal-Wallis test), with no difference between NDC and FDC. In conclusion, our multicenter study shows that a prevalent exposure to a male dog represents a risk factor for the presence of Can f 5 monosensitization in Italy.