Cypress Pollen-Peach Cross-Reactivity: The Emerging Role of Pru p 7 as a Marker of Severe Allergic Phenotypes

Background: The peach allergen Pru p 7, a member of the Gibberellin-Regulated Protein (GRP) family, has emerged as a key marker of severe fruit-induced allergies. It is hypothesized to mediate cross-reactivity between fruit allergens and cypress pollen. Given the increasing prevalence of food allergies and the complex patterns of cross-sensitization, the role of Pru p 7 in clinical allergy diagnostics warrants further investigation. Objective: This study aims to characterize the sensitization profile to Pru p 7 in a cohort of patients with suspected fruit allergy and to assess its relationship with cypress pollen allergy, particularly to Cup s 7, a homologous GRP from Cupressus sempervirens. Methods: A retrospective analysis was conducted on 20 patients evaluated at the Allergy Unit of the Fondazione IRCCS Policlinico San Matteo. Specific IgE (sIgE) levels to peach extract, Pru p 7, and Cup a 1 (cypress extract) were assessed using the ImmunoCAP® system (Thermo Fisher Scientific Inc., Waltham, MA, USA). Statistical associations between sensitizations were evaluated using chi-square tests and Spearman’s correlation. Results: Sensitization to peach extract, Pru p 7, and cypress pollen was detected in 38%, 30%, and 45% of patients, respectively. Significant associations were observed between peach and cypress (χ2 = 8.80, p = 0.003), peach and Pru p 7 (χ2 = 8.23, p = 0.004), and cypress and Pru p 7 (χ2 = 6.55, p = 0.01). Notably, all patients sensitized to Pru p 7 also tested positive for both peach and cypress allergens, supporting the hypothesis of pollen–food cross-reactivity. Conclusions: Pru p 7 is a clinically relevant allergen that may account for severe allergic responses in patients not sensitized to classical peach allergens. Its cross-reactivity with Cupressaceae-derived GRPs, such as Cup s 7, highlights the importance of molecular diagnostics in evaluating food allergies, particularly in regions with significant exposure to cypress pollen.