Table 1.

Partial list of proteins and other molecules that we are exposed to in a house with a cat

Molecule	Allergen Name	Nature of Epitope	Inhalant Allergen	Prevalence of Sensitization	Cross-reactivity
Uteroglobin‡	Fel d 1	Protein	+++	≥ 90%	Other cats
Cat albumin	Fel d 2	Protein*	±	5%	Pork and other albumins
Cat IgA	Fel d 5w	Oligosaccharide#	No	0–15%#	Selected proteins in all mammals
Lipocalin	Fel d 4	Protein	Unknown	?	Can f 2
Cat DNA¶	-	NR	-	-	-
Endotoxin†	-	NR	-	-	-

^‡The function of the protein in the cat is not well understood.

^*Primary sensitization to cat (or dog) albumin with cross-reactivity to pork (and sometimes beef) albumin (i.e., pork-cat syndrome).

^#The epitope is galactose-α-1,3-galactose and the prevalence of sensitization is highly dependent upon the prevalence of tick bites [27].

^¶Cat DNA, as with other mammalian DNA, is fully methylated.

^†Although cats produce endotoxin, it is not clear that airborne endotoxin is increased in homes with a cat.