Allergic rhinoconjunctivitis (AR) is the most frequent
IgE-mediated disease, with its prevalence reaching 40% in
some surveys.1-3 Depending on sensitization status, symptoms
can be precipitated by seasonal/outdoor aeroallergens (eg,
pollen), perennial/indoor aeroallergens (eg, house dust mites
[HDMs] and cockroaches), or both.4,5 Sensitization to the most
common classes of aeroallergens is typically assessed by using
skin prick test (SPT) responses.4,5 However, even among patients
with sensitization to multiple aeroallergens, the severity of AR
symptoms varies widely.4,5 Interindividual differences in AR
symptom severity might relate to differences in aeroallergen
concentrations in the environment. Another possibility is that
even after controlling for concentration, sensitization to specific
aeroallergens might modify the severity of AR symptoms elicited
on exposure to another aeroallergen but not the sensitizing
allergen. In other words, it is not the number of positive SPT
responses per se but rather the presence of versus the lack of
sensitization to specific aeroallergens that underpins interindividual
variation in AR symptom severity.