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 analyzed 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 amino acid sequences of 63 residues in length, 94-98% 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 & 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.