Fel d 1 production in the cat skin varies according to anatomical sites

Fel d 1 is the major cat allergen, inducing asthma in sensitized individuals. It is produced by the skin and lies on fur. Recently, it was established that the amount of Fel d 1 on fur varies among anatomical sites. However, it is not known whether the allergen production by skin varies in parallel. The objective was to compare the Fel d 1 production by male cat skin in two anatomical sites, the face and the chest, in order to correlate it with Fel d 1 amounts on fur, and to assess the reaccumulation of Fel d 1 after washing.

Ten intact male cats were shaved under general anesthesia at both areas, and the fur was collected. The skin was washed and the washing fluid collected for Fel d 1 assays. Fel d 1 levels were measured in microg/g fur and ng/cm2 skin by ELISA before and after washing and 48 h later.

In skin washing, the mean Fel d 1 level was significantly higher in the face (1015.2 +/- 821.6 ng/cm2) than the chest (115.2 +/- 66.8 ng/cm2). In the fur, the respective levels were 63.6 +/- 34 and 29.6 +/- 13.6 microg/g. In the skin sample taken after skin washing, the level of Fel d 1 dropped to 25.1 +/- 25.7 ng/cm2 on the face and to 22 +/- 17.4 ng/cm2 on the chest. After 2 days, skin Fel d 1 levels returned to basal values, with higher values on the face than the chest.

This study shows that Fel d 1 levels on the skin are dramatically higher on the facial area than chest. This anatomical variation is concordant with the levels of Fel d 1 found on fur. Washing reduces levels of major allergen on cat skin and fur, but the accumulation on skin is restored within 2 days.