Proteomic profiling of Juniperus oxycedrus and Cupressus arizonica pollen reveals quantitative interspecies differences in the IgE-binding protein repertoire associated with Mediterranean Cupressaceae allergy.

BACKGROUND

Diagnosis and allergen-specific immunotherapy for Mediterranean allergy rely on extracts standardized to group-1 allergens, such as Cup a 1 from Cupressus arizonica, potentially overlooking interspecies variability. The native species Juniperus oxycedrus, widespread in Spain, may contribute to sensitization, but its clinical relevance and allergen repertoire remain poorly characterized.

OBJECTIVE

To characterize and compare the allergen and IgE-binding protein composition of J. oxycedrus and C. arizonica pollen extracts and assess their sensitizing relevance in Spain.

METHODS

Pollen extracts were analyzed using SDS-PAGE, two-dimensional electrophoresis (2-DE), Western blotting (WB), and mass spectrometry (MS). 241 patients with allergic rhinitis and/or conjunctivitis from seven Spanish regions underwent skin prick testing and specific IgE for extracts and Jun o 1/Cup a 1, by ELISA. Cross-reactivity was assessed by competitive ELISA and WB inhibition.

RESULTS

Proteomics and 2-DE showed a more complex protein profile in J. oxycedrus than in C. arizonica pollen extract (423 vs. 251 proteins, 146 shared). Among patients, 35% were sensitized to Cupressaceae, with more frequent monosensitization to J. oxycedrus. 2-DE/WB showed ≥60 IgE-binding spots in J. oxycedrus vs. 5 in C. arizonica, including group-1 allergen isoforms and IgE-reactive components (calreticulin, superoxide dismutase, aconitate hydratase, aldose 1-epimerase, and enolase) with lower abundance in C. arizonica. Inhibition assays indicated high but asymmetric cross-reactivity, consistent with the differences in IgE-binding protein abundance.

CONCLUSION

J. oxycedrus and C. arizonica pollen extracts display broadly similar IgE-reactive repertoires but differ in the relative abundance. Such differences may affect regional sensitization and limit the effectiveness of group 1-based diagnosis and therapy.