Background: Profilin is a highly conserved protein regarded as a pan-allergen in pollen and vegetable food. Homologous proteins from different sources are highly cross-reactive.

Objective: To assess whether detecting immunoglobulin (Ig) E to multiple profilins from different sources is clinically more useful than detecting IgE to a single representative profilin.

Methods: Sera from 43 subjects sensitized to profilin selected in 2 allergy centers in Northern Italy showing a different pollen exposure profile were studied for their IgE reactivity to 5 profilins (Bet v 2, Ole e 2, Hev b 8, Mer a 1, and Phl p 12) using a commercial allergen microarray immunoassay.

Results: All 43 patients (100%) scored positive to at least 1 profilin on ISAC, although reactivity to all 5 profilins was observed in only 37 cases (86%). In approximately half of the reactors, IgE reactivity to Ole e 2 was much weaker than that to other profilins irrespective of the primary sensitizing allergen source, suggesting a low sensitivity of this allergen. Much discrepancy in IgE to Bet v 2 measured by ISAC microarray and ImmunoCAP was observed.

Conclusion: Detecting IgE reactivity to a single marker protein (eg, Bet v 2) is sufficient to diagnose or exclude sensitization to profilin. Detecting IgE to multiple homologous, cross-reacting allergen proteins is not clinically more informative and increases the risk of confusion and misinterpretation.

Key words: Profilin. Pan-allergens. Cross-reactivity. IgE. Microarray.