Detection of specific IgE antibodies towards cat flea (Ctenocephalides felis felis) in patients with suspected cat allergy.

Cat flea sensitivity is considered one of the most important skin diseases in cats and dogs. Cat fleas, however, are also a growing allergen problem for humans. Cat flea-specific IgE antibodies were studied in serum samples from 70 patients with suspected cat allergy, using RAST-based techniques and the nitrocellulose immunoblotting method. Results from RAST studies, using cat and cat flea as allergosorbents, showed that 46% of the patients were RAST positive against both cat and cat flea. 9% of the patients were RAST positive only against the cat flea. The nitrocellulose immunoblotting experiments were in agreement with the RAST results showing specific IgE to cat flea. The results indicate that some cat-allergic patients have specific IgE both towards cat and cat flea but also that some of the patients with suspected cat allergy might have specific IgE towards the cat flea and not the cat. RAST-inhibition and immunoblotting experiments also indicate that the allergen composition of cat flea extract differs from that of cat extract, even if common allergens have been detected, leading to cross-reactivity in some sera.