Cat and dog allergies
In general, the severity and progression of cat and dog allergies involve IgE recognition of a progressively increasing number of components from the sensitizing allergen source (molecular spreading)30,62-65.
The availability of CRD for different cat and dog allergens has also raised the possibility of more precisely targeted AIT, mainly because it may distinguish primary sensitization from cross-sensitization, thereby enabling selection of the primary sensitizing allergen source for therapy.
In a recent, comprehensive study66, including most of the components available, the pattern of IgE sensitization to cat allergens showed that 92% of cat-allergic patients had positive IgE antibodies results to Fel d 1. Other allergens also seem important, such as Fel d 4 and Fel d 7. Previous studies reported similar results67. The content of Feld d 1 in allergenic extracts varies substantially. Nevertheless, it has been demonstrated that the maintenance efficacy dose of Fel d 1 is 15 mg/ml68.
In the same study, in patients with dog allergy, 52.4% were positive to Can f 1, and 57.2% to Can f 5. The most frequent monomolecular sensitization was to Can f 5.
The content of different dog allergen molecules in European AIT extracts has been recently studied69. These authors demonstrated great variability in extracts from five companies and scarce content of major allergens70.
In general, AIT with cat extracts yield better clinical results than with dog ones. The higher complexity of dog allergy sensitization patterns, the lack of preparations with an adequate balance of major allergens is likely to explain this divergence66,71,72.
Further studies are needed to determine whether CRD could be used to identify patients who are most likely to respond to AIT specially in dog allergy.
Figure 5 summarizes decision-making algorithms in cat and dog allergy AIT selection.