We aimed to determine the profile of IgE reactivity to three major cat allergens, Fel d 1, Fel d 2 and Fel d 4, in cat-allergic patients in the Moscow region in Russia. sIgE levels to recombinant proteins expressed in Escherichia coli (Fel d 1 and Fel d 4) and to Fel d 2 protein purified from cat serum were measured using a microarray method developed in our laboratory. Sera from 174 anonymous subjects with a positive reaction (≥0.35 IU/mL) to cat dander extract (e1, ImmunoCAP) and 56 negative controls were used for IgE testing. Fel d 1 was recognized by 92.5%, Fel d 2 by 29.9% and Fel d 4 by 39.1% of the tested patient sera. The sensitivity to these three proteins was approximately 98% compared to cat dander extract (correlation coefficient to ImmunoCAP is 0.94 with PPV = 0.99 and NPV = 0.95). These predictive values appeared to be even more statistically significant than the divergence between the ISAC IgE test and the extract-based singleplex ImmunoCAP. The combination of the three investigated proteins (Fel d 1, Fel d 2 and Fel d 4) is suitable for in vitro molecular (serological) diagnosis of cat allergy in this region as a complement to cat dander extract. Moreover, with this method, we found distinction between Fel d 2 and other Feline sIgEs formation.
Keywords: Allergy diagnostics; Fel d 1; Fel d 2; Fel d 4; antigen-specific IgE; cat allergy; sensitization profiles.