The degree of serological sensitization to cat allergen in patients with or without cat at home.

Background: The relationship between exposure to cat/dog in domestic environments and development of allergic sensitization to pet allergens is still controversial.

Objective: To test the role of indirect exposure to cat, we aimed to evaluate the amounts of cat specific IgE in sensitized subjects with or without cat at home.

Methods: Three hundred six adult patients with a previous diagnosis of allergic sensitization to cat allergens (by skin prick test) were enrolled for this study. Among 306 men and women sensitized to cat (and other allergens), 150 owned a cat for at least 10 years ( direct exposure) and 156 had never owned this animal (indirect exposure). An internal questionnaire specifically designed for the study was completed by the same allergists during the screening consultation: the results of skin prick tests, personal and clinical data, periods of symptoms and characteristics of cat ownership were carefully recorded. Specific IgE to cat extract was determined by the Pharmacia CAP System FEIA (Pharmacia Diagnostics, Uppsala, Sweden) and Immulite 2000 (Diagnostic Products Corporation, Los Angeles, USA) RESULTS: Although specific IgE to cat allergen were significantly higher in patients with cat at home (F = 42.77; p < 0.001), high amounts of these antibodies were found also in sera of subjects indirectly exposed to cats.

Discussion: The results of our study demonstrate that the degree of serological sensitization to cat allergens may be relevant also in subjects without any direct contact with cats (indirect exposure).