Capsicum Allergy: Involvement of Cap a 7, a New Clinically Relevant Gibberellin-Regulated Protein Cross-Reactive With Cry j 7, the Gibberellin-Regulated Protein From Japanese Cedar Pollen

The Capsicum genus belongs to the Solanaceae family. Bell or chili peppers are consumed worldwide, but allergy to Capsicum is rare. It is involved in the celery-birch-mugwort-spice syndrome and cross-reactivities were reported with latex. Several allergens have been described, but only 2 are referenced in the World Health Organization/International Union of Immunological Societies allergen data bank, a thaumatin-like protein and a profilin. A patient allergic to bell/chili pepper, peach, orange and Japanese cedar pollen was clinically and biologically analyzed including direct and competitive immunoblots and basophil activation tests (BATs) with allergenic source extracts and recombinant gibberellin-regulated proteins (GRPs). The patient was shown to be sensitized to Cap a 7, the GRP of Capsicum annuum newly described herein. Cross-reactivities were demonstrated between various GRPs from bell/chili pepper, peach, orange and Japanese cedar pollen either in native form in the different extracts or as recombinant allergens. A similar immunoglobulin E reactivity was found also in Capsicum chinense and against snakin-1, the GRP from potato. The patient showed a positive BAT with recombinant Cry j 7, Pru p 7 and Cap a 7, but not with recombinant snakin-1. Despite the ubiquitous nature of GRPs in plants and the immunochemical cross-reactivity observed between different GRPs, clinically relevant sensitization to this protein family seems restricted to some allergenic sources, often associated with Cupressaceae pollen allergy, and to some patients, therefore reflecting very specific and peculiar mechanisms of conditional sensitization.