Methods: We studied IgE binding patterns in 311 patients sensitized to cat, dog and/or horse (123m/188f, mean age 32±17 yrs) using Phadia ImmunoCAP®for rFel d 1, serum albumins (nFel d 2/nCan f 3), lipocalins (rFel 4/rCan f 1/rCan f 2/rEqu c 1), and rCan f 5.
Results: Skin tests were positive to more than one species in 50.8%. In cat sensitization, reactivity with Fel d 1/2/4 was 87/2/7% in patients positive to cat alone (n=134), 91/11/25% in patients positive to cat+dog (n=75), and 86/37/76% in those positive to cat+dog+horse (n=62). In dog allergy, reactivity with Can f 1/2/3/5 was 32/0/5/53% in patients positive to dog alone (n=19), 36/4/11/26% in patients positive to cat+dog (n=75), and 53/16/37/26% in those positive to cat+dog+horse (n=62). Can f 1, 2 and 5 represented dog-specific allergens particularly recognized by dog owners (p<0.001). Anyhow, symptoms after dog exposure were similarly frequent in subjects either positive or negative to Can f 1/2/5 (79 vs. 66%). Equ c 1 was the major allergen (85%) in patients sensitized to horse and horse+cat (n=20). Equ c 1 correlated with Fel d 4 (r=0.72), and ~50% of patients reported adverse reactions to both animals. No correlation was found between other lipocalins.
Conclusions: Current CRD can often, but not always, explain polysensitization. As cross-reactions appear to be often clinically relevant, the practical benefit from discriminating between genuine sensitization and cross-sensitization might be limited in clinical practice.