Characterization of a 7 kDa pollen allergen belonging to the gibberellin-regulated protein family from three Cupressaceae species.

BACKGROUND: Severe allergy to fruits mediated by a 7 kDa allergen belonging to the gibberellin-regulated protein (GRP) family is known to be associated with Cupressaceae pollinosis. OBJECTIVE: To identify and characterize Cupressaceae pollen allergens involved in GRP-related fruit allergy. METHODS: Pru p 7-related proteins from pollen of Cupressus sempervirens, Juniperus ashei and Cryptomeria japonica were identified using a rabbit anti-Pru p 7 antiserum, purified chromatographically and sequenced by mass spectrometry and bioinformatic comparisons. The C sempervirens protein was produced as a recombinant allergen in Pichia pastoris. IgE antibody binding to pollen GRP proteins was analysed in a peach allergic (n = 54) and a cypress pollen allergic (n = 88) patient population from southern France using ImmunoCAP. RESULTS: In each of the three Cupressaceae species studied, a 7 kDa pollen protein related to Pru p 7 was identified and found to comprise an amino acid sequence of 63 residues in length, 92%-98% identical to each other and 67%-68% identical to Pru p 7. The C sempervirens, J ashei and C japonica GRP allergens have been officially recognized by the WHO/IUIS Allergen Nomenclature Sub-Committee and named Cup s 7, Jun a 7 and Cry j 7, respectively. Recombinant Cup s 7 showed IgE antibody binding capacity comparable to that of the purified natural allergen. Among 51 peach allergic subjects sensitized to Pru p 7, substantially higher levels of IgE to Cup s 7 than to Pru p 7 were found. Further, the pollen protein was able to completely outcompete IgE binding to Pru p 7, while the reverse competition effect was modest, consistent with primary sensitization by the pollen allergen. CONCLUSION AND CLINICAL RELEVANCE: Pru p 7-related pollen allergens from three Cupressaceae species have been characterized and may become useful for the identification of pollinosis patients at risk of developing severe fruit allergy.

Pru p 7 sensitization is a predominant cause of severe, cypress pollen-associated peach allergy.

BACKGROUND: Peach is a common elicitor of food allergic reactions. Peach-induced immediate reactions may occur as benign pollen-food syndromes, usually due to birch pollen-related PR-10 cross-reactivity in temperate climates, and as potentially severe primary food allergies, predominantly related to nsLTP Pru p 3 in Mediterranean regions. The newly described peach allergen Pru p 7 has gained recent attention as a potential peach allergy severity marker. Sensitization to Pru p 7 and its allergenic homologues of the gibberellin-regulated protein family occurs in areas with high Cupressaceae tree pollen exposure. OBJECTIVE: We sought to investigate the distribution, clinical characteristics and molecular associations of Pru p 7 sensitization among subjects with suspected peach allergy in different regions of France. METHODS: Subjects with suspected peach allergy (n = 316) were included. Diagnostic work-up was performed according to current guidelines, including open food challenge when required. IgE antibody measurements and competition experiments were performed using the ImmunoCAP assay platform. RESULTS: Sensitization to Pru p 7 was present in 171 (54%) of all subjects in the study and in 123 of 198 (62%) diagnosed as peach allergic, more than half of whom were sensitized to no other peach allergen. Frequency and magnitude of Pru p 7 sensitization were associated with the presence of peach allergy, the clinical severity of peach-induced allergic reactions and the level of cypress pollen exposure. Cypress pollen extract completely outcompeted IgE binding to Pru p 7. Pru p 7 was extremely potent in basophil activation tests. CONCLUSION AND CLINICAL RELEVANCE: A subtype of Cupressaceae pollinosis, characterized by Pru p 7 sensitization, can be an underlying cause of severe peach allergy.