Cat
allergy is a major trigger factor for respiratory reactions (
asthma and
rhinitis) in patients with
immunoglobulin E (
IgE) sensitization. In this study, we used a comprehensive panel of purified cat
allergen molecules (rFel d 1, nFel d 2, rFel d 3, rFel d 4, rFel d 7, and rFel d 8) that were obtained by recombinant expression in Escherichia coli or by purification as natural
proteins to study possible associations with different phenotypes of cat
allergy (i.e.,
rhinitis,
conjunctivitis,
asthma, and
dermatitis) by analyzing molecular
IgE recognition profiles in a representative cohort of clinically well-characterized adult cat allergic subjects (n = 84).
IgE levels specific to each of the
allergen molecules and to natural cat
allergen extract were quantified by ImmunoCAP measurements. Cumulative
IgE levels specific to the cat
allergen molecules correlated significantly with
IgE levels specific to the cat
allergen extract, indicating that the panel of
allergen molecules resembled
IgE epitopes of the natural
allergen source. rFel d 1 represented the major cat
allergen, which was recognized by 97.2% of cat allergic patients; however, rFel d 3, rFel d 4, and rFel d 7 each showed
IgE reactivity in more than 50% of cat allergic patients, indicating the importance of additional
allergens in cat
allergy. Patients with cat-related skin symptoms showed a trend toward higher
IgE levels and/or frequencies of sensitization to each of the tested
allergen molecules compared with patients suffering only from
rhinitis or
asthma, while there were no such differences between patients with
rhinitis and
asthma. The
IgE levels specific to
allergen molecules, the
IgE levels specific to cat
allergen extract, and the
IgE levels specific to rFel d 1 were significantly higher in patients with four different symptoms compared with patients with 1-2 symptoms. This difference was more pronounced for the sum of
IgE levels specific to the
allergen molecules and to cat extract than for
IgE levels specific for rFel d 1 alone. Our study indicates that, in addition to rFel d 1, rFel d 3, rFel d 4, and rFel d 7 must be considered as important cat
allergens. Furthermore, the cumulative sum of
IgE levels specific to cat
allergen molecules seems to be a
biomarker for identifying patients with complex phenotypes of cat
allergy. These findings are important for the diagnosis of
IgE sensitization to cats and for the design of
allergen-specific
immunotherapies for the treatment and prevention of cat
allergy.