Fel d 1
is a protein
that in cats is encoded by the CH2 gene
Fel d 1, produced largely by cat saliva
and sebaceous glands
, is the primary allergen
present on cats. The protein is of an unknown function to the animal but causes an IgG
reaction in sensitive humans (either as an allergic or asthmatic response). Removal of soft surfaces in the home (carpet, furniture), frequent washings of bed linens, HEPA
filters and even washing cats have been proven to reduce the amounts of Fel d 1 present in the home. Fel d 1 is a particularly sticky protein and has been shown to cling to clothing and human hair and can be detected in environments where a cat has never been present.
Cats produce, on average, 2-7 µ
of Fel d 1 per day. Studies have shown that intact males produce Fel d 1 in levels higher than castrated males, leading to the assumption that Fel d 1 is hormonally regulated by testosterone
. Neutered males produce Fel d 1 in levels similar to females (both intact and spayed females produce Fel d 1 in similar levels). Even though females and neutered males produce Fel d 1 in lower levels, they still produce enough to cause allergic symptoms in sensitive individuals.
Fel d 1 is an 18 kDa heterodimer
protein and belongs to the secretoglobin
family of small disulfide linked dimeric proteins found only in mammals.