Jun o 1, a Cross-reactive Juniperus oxycedrus Allergen With Unique Structural and Immunogenic Properties

Juniperus oxycedrus, from the Cupressaceae family, is widespread in the Mediterranean. However, the allergenic relevance of its pollen remains underexplored. Objective: This study aimed to characterize Jun o 1, an allergen of J oxycedrus that is homologous to major allergens in related species.

Native Jun o 1, its nonglycosylated Escherichia coli-expressed form (rJun o 1), and Cup a 1 were purified by affinity chromatography. Jun o 1 was characterized by SDS-PAGE, 2D-electrophoresis, Western blot (WB), and mass spectrometry and compared with the homologous cypress allergen, Cup a 1. Enzymatically and chemically deglycosylated Jun o 1 was also analyzed. Specific IgE binding and cross-reactivity were evaluated using ELISA, WB, and mast cell activation assays with sera from 57 Spanish cypress-allergic patients. IgG binding was tested using sera from rJun o 1-immunized mice.

Jun o 1 exists as multiple isoforms and assembles into oligomers, whereas Cup a 1 comprises multiple isoforms without oligomerization. IgE binding to Jun o 1, including mast cell activation, is critically influenced by the combined presence of protein and carbohydrate determinants. Compared to Cup a 1, Jun o 1 exhibited greater IgE-binding inhibition for J oxycedrus extract in sera from Cupressaceae-sensitized allergic patients from this tree's autochthonous regions. The highest rate of monosensitization in this group was to J oxycedrus.

Jun o 1 is a relevant and potential major allergen in cypress allergy. Structural and immunogenic similarities with Cup a 1 lead to cross-reactivity, although it also exhibits unique properties, resulting from combined IgE-reactive protein and glycan determinants.