000491 - Cross-reactivity Analysis of 24 Pollen Allergens in Tomato Allergy: Identification of β-Expansin as a Novel Causative Allergen in Pollen–Food Allergy Syndrome

Tomato allergy (TA) is associated with sensitization to multiple pollens. However, most previous studies have focused on single pollen allergens, and the mechanisms underlying TA in patients with multiple allergen sensitizations remain unclear. To serologically investigate pollen allergen sensitization profiles associated with tomato allergy.

Among 3,646 patients who visited Fujita Health University Bantane Hospital between 2018 and 2025 and provided informed consent, 23 patients who reported symptoms after tomato ingestion and showed positive skin prick test (SPT) responses to tomato were enrolled. Serum IgE reactivity to 24 pollen allergens derived from eight pollens (Japanese cedar, cypress, orchard grass, timothy grass, alder, birch, mugwort, and ragweed) was evaluated by ELISA. Inhibition ELISA using crude tomato extract was performed, and an inhibition rate ≥50% was considered positive.

Clinical manifestations included oral allergy syndrome alone in 11 of 23 patients, lip swelling in three patients, and eyelid swelling in two patients. Tomato-specific IgE was positive in 11 patients (48%). ELISA showed positive IgE reactivity to cedar polygalacturonase in all patients (100%), grass pollen β-expansin in 11 patients (48%), birch PR-10 in eight patients (35%), and grass pollen profilin in six patients (26%). In inhibition ELISA, inhibition was observed for polygalacturonase in 2 of 23 cases (8%), β-expansin in 8 of 11 cases (72.7%), PR-10 in 2 of 8 cases (25%), and profilin in all 6 cases (100%). No clear association was observed between clinical symptoms and tomato-specific IgE levels or allergen reactivity. Five patients sensitized to grass pollen were negative for profilin but positive for β-expansin.

Although multiple pollen allergens were involved in sensitization, β-expansin (Phl p 1/Dac g 1) was newly identified as a causative pollen allergen of pollen–food allergy syndrome associated with tomato-grass allergy.