Molecular allergy diagnosis is sensitive and avoids misdiagnosis in patients sensitized to seasonal allergens

BACKGROUND: The specificity of extract‐based pollen allergy diagnosis is decreased due to cross‐reactivity via cross‐reactive carbohydrate determinants (CCDs) or panallergens such as profilins or polcalcins.

This study aimed to explore the prevalence of sensitization to seasonal extracts, CCDs, profilin and polcalcin and investigate the sensitivity and specificity of seasonal molecular allergy diagnosis (MAD) using commercially available test methods.

METHODS: 2948 patients were screened for specific immunoglobulin E to ash, birch, mugwort, ragweed and timothy grass pollen extracts and grouped according to the number of positive tests (1–5).

100 patients from each group and a control group were randomly selected to calculate the prevalence of CCD and panallergen sensitization.

With 742 patients, sensitivity and specificity of MAD (Alt a 1, Fra/Ole e 1, Bet v 1, Phl p 1, Art v 1, and Amb a 1) was determined.

RESULTS: 1627 patients (55.2%) were positive to at least one, and 1002 patients (34.0%) were positive to multiple of the five pollen allergens investigated; 18.5% of the pollen‐sensitized patients had sensitization to CCDs or panallergens.

Specifically, sensitization to CCDs, profilins, and polcalcins was observed in 8.7%, 10.9%, and 2.9% of these patients, respectively.

The sensitivity of MAD was high, with sensitivities between 96.2% and 100% using ImmunoCAP and 91.5% and 100% using ALEX(2).

Specificity was 100% for both assays.

CONCLUSIONS: Due to cross‐reactivity, about one‐fifth of pollen‐sensitized patients is at risk of misdiagnosis.

However, MAD is sensitive, specific and helps to avoid misdiagnosis and select primary allergen sources for immunotherapy.