SEX DIFFERENCE IN FEL-D-1 ALLERGEN PRODUCTION

Background: Previous experiments have shown that in vivo Fel d 1 produ ction is under hormonal control. It strongly decreased 1 month after c astration of male cats and increased after testosterone injection. Obj ective: These results led us to put forward the hypothesis that Fel d 1 production could be more important in male than in female cats. Five adult male and five adult female cats were studied Methods: On day 0 three separate sites of each cat's trunk were shaved, and a 5.72 cm(2) area in each site was washed twice (D0a and D0b) with 5 ml of distill ed water: Then a collar was attached to the neck to prevent contaminat ion from saliva. Twenty-four hours Inter on day 1, all areas were wash ed again once (D1a). Skin washes and fur extracts from the shaved area s were evaluated for Fel d 1 content. The same procedures (apart from collection of fur) were repeated 5 months later: Results: The Fel d 1 level was higher in the first skin wash of male cats compared with tha t of female cats on each separate sire of the trunk in both experiment s, initially and 5 months Inter: Results were significant in the first experiment (median Fel d I per milliliter: 69.4 and 28.9 mU, respecti vely, for the combined three sites; p < 0.05). Fel d 1 production over a 24-hour period was higher in male cats, but the difference did not reach statistical significance. Furthermore, correlation between Fel d 1 levels in washes D0a and in fur was highly significant (p < 0.01). Conclusion: These, results confirm that Fel d 1 originates from skin. Furthermore, they suggest that Fel d 1 production is higher in male th an in female cats.