Biochemical Characterisation of Major Allergens in Tropical Fruits and Their Clinical Significance

The purpose of this study was to investigate the biochemical properties and clinical significance of immunoreactive proteins from tropical fruits in the Republic of Poland. The methodology included protein extraction from mango, pineapple, papaya, and kiwi, followed by electrophoretic analysis (SDS-PAGE, 2D electrophoresis), MALDI-TOF mass spectrometry, and immunological tests (ELISA and western blotting) using sera from 56 patients with confirmed fruit allergies. The results showed clear differences in protein composition, with kiwi and mango exhibiting the highest number and intensity of protein fractions (36 and 31 spots, respectively) in the mass range of 10–80 kDa and pI 4.5–6.8. A total of 14 unique proteins with high homology (68–95%) to known allergens, including profilins, thaumatin-like proteins, actinidin, papain, and bromelain, were identified. In kiwi and mango, more than 80% of patients demonstrated high IgE reactivity, resistance to heat and enzymatic treatment, and a significant correlation (p = 0.84, p < 0.001) between protein stability and immunoreactivity. Papaya and pineapple showed lower reactivity (less than 50%) and greater sensitivity to processing. Kiwi proteins (especially actinidin and profilin) showed the strongest immunoreactivity, which persisted after treatment. Cross-sensitisation to several fruits was detected in 21.4% of patients, mainly involving structurally stable proteins. Overall, the findings establish the high clinical significance of kiwi and mango allergens and highlight the need for molecular diagnostics and personalised recommendations for sensitised patients.