Optimization of the diagnosis and characterization of gibberellin-regulated protein sensitization: An Italian cohort study.

Background: Pru p 7 was the first gibberellin-regulated protein (GRP) to be identified as a food allergen as the basis of a pollen food allergy syndrome.

Objective: To clinically and biologically characterize a group of patients with suspected allergy to Pru p 7 to optimize the diagnostic workup of GRP sensitization.

Methods: Allergy to Pru p 7 was suspected in the presence of a systemic allergic reaction to plant food, positive skin prick test results for cypress pollen and lipid-transfer protein-enriched peach extract, and absence of Pru p 3-specific immunoglobulin E. Controls were patients with food allergies, patients sensitized to Pru p 3, and patients with cypress allergy without food allergy. Diagnostic workup included skin tests, basophil activation test, Western blot, and single and multiplex assays.

Results: In total, 23 patients and 14 controls were enrolled. The most implicated food was peach (91.3%). Approximately 70% of patients reacted to multiple foods. Mueller 4 reactions were 8.7%. In 26.1% of cases, a cofactor triggered the reaction. The basophil activation test results were positive for rPru p 7 in 87% of the patients. Specific immunoglobulin E to Pru p 7 was detected in 95.7% by singleplex and in 73.9% by multiplex assays in patients with suspected allergies; 73.9% of them also reacted to cypress pollen GRP (Cup s 7) in Western blot analysis.

Conclusion: Patients with Pru p 7-Cup s 7 allergy in our cohort confirm a mild-to-severe clinical syndrome characterized by pollen and food allergy. The diagnosis may benefit from the proposed selection criteria that can be used as preliminary steps to further characterize the cross-reactive GRP sensitization.