Background: Polcalcins are highly cross-reactive pollen panallergens. Less than 10% of allergic patients are sensitized to polcalcins. All pollen species are considered able to sensitize patients to this panallergen.

Objective: We aimed to assess the presence of polcalcins in various pollen extracts used in allergen immunotherapy.

Methods: ELISA inhibition experiments were performed with sera from patients sensitized to polcalcin and rPhl p 7 and rBet v 4. Recombinant polcalcin was used as the substrate and freshly prepared pollen extracts as inhibitors.

Results: All pollen extracts induced significant inhibition of IgE reactivity to rBet v 4, whereas only grass pollen extract induced marked inhibition of IgE reactivity to rPhl p 7.

Conclusion: Grass polcalcin probably contains more epitopes than polcalcins from other pollen sources. Grass pollen could be responsible for sensitization to polcalcins, and grass pollen immunotherapy is likely to be an option for polcalcin-hypersensitive patients.

Key words: Polcalcin, Pollen allergy, Panallergens, Sensitization, Cross-reactivity.