Is Fel d1 Based Component Resolved Diagnosis Associated With Airway Inflammation in Cat Sensitized Children?

In cat sensitized children, decision to eliminate exposure to cats depends on the clinical outcome. In this study, we aimed to examine the relationship between molecular cat allergen sensitization and exhaled breath condensate (EBC) IL-4, IL-5, and IL-13 as markers of allergic airway inflammation. We enrolled subjects with skin prick test diagnosis of cat allergen sensitization aged 4-17 years. Age, sex, diagnosis, and clinical symptoms as well as family history of allergic diseases were recorded at enrollment along with the association of symptoms and cat exposure. Asthma severity and allergic rhinitis symptom score were recorded. Blood samples were collected for Fel d1 based component resolved diagnosis (CRD/FEL D1) and exhaled breath samples were collected for measurement of IL-4, IL-5, and IL-13. Among the 80 subjects (40 boys) enrolled, antibody positivity for Fel d1 was 74%. Cat exposure outdoors was more common in children with Fel d1 positivity (37% vs. 14%, p = 0.02). Asthma respiratory symptom severity score was significantly higher in Fel d1 antibody positive subjects (p = 0.01). On the other hand, EBC levels of IL-4, IL-5 or IL-13 were not found to be significant different between subjects with and without Fel d1 positivity (48.8 vs. 63.3, p = 0.59; 6.9 vs. 14.4, p = 0.62; 4.0 vs. 5.3, p = 0.83, respectively) The results of our study suggest a possible association between CRD/FEL D1 positivity and more severe respiratory symptoms in asthmatic children but not airway inflammation emphasizing the importance of interpretation of CRD results in the context of clinical findings.