Profilin isoallergens, major but not immunodominant, from Korean melon

Abstract

Background: Pollen food allergy syndrome (PFAS) is a common condition caused by cross-reactivity between pollen allergens and homologous proteins in certain fruits, vegetables, and nuts. Korean melon (Cucumis melo var. makuwa) is a frequent trigger of PFAS; however, its allergenic components have not been fully characterized. Objective: This study aimed to identify the allergens responsible for PFAS in Korean melon and investigate potential differences in allergenic profiles among melon cultivars. Methods: Allergen extracts from Korean melon were analyzed using proteomic and transcriptomic approaches. Profilin isoallergens (Cuc m 2.0102 and Cuc m 2.0301) were recombinantly expressed, and IgE reactivity was evaluated by ELISA and immunoblotting. Profilin content in melon extracts was quantified using targeted mass spectrometry. Results: IgE immunoblotting of melon extracts revealed 3 allergenic components at approximately 60, 15, and 12 kDa. Proteomic analysis identified profilin (Cuc m 2) as the only allergen identified, whereas transcriptomic analysis additionally identified cucumisin (Cuc m 1) and pathogenesis-related protein 1 (PR-1; Cuc m 3). Two profilin isoallergens, Cuc m 2.0102 and Cuc m 2.0301, were identified, with Cuc m 2.0102 showing the highest identity to the canonical Cuc m 2.0101. Profilin abundance was lower in Korean melon than in other cultivars, including honeydew melon and Hami melon, and did not account for the majority of IgE reactivity. Inhibition assays further suggested that profilin is not the immunodominant allergen in patients with Korean melon. In contrast, sensitization to the 60 kDa allergen, a potential cucumisin (Cuc m 1), which was identified by transcriptomics, may reflect primary sensitization to Korean melon. Conclusion: Profilin isoallergens Cuc m 2.0102 and 2.0301 were identified as major but not immunodominant allergens associated with PFAS in Korean melon. Variation in profilin content among melon cultivars suggests differences in allergenic potential. These findings contribute to the understanding of PFAS and may support the development of improved diagnostic approaches and allergen avoidance strategies.