Background: The clinical features of many patients with oral allergy syndrome (OAS) due to plant-derived foods have rarely been reported in Japan.
Objectives: We aimed to determine the causative foods of OAS due to plant-derived foods based on clinical features and skin prick tests (SPTs). Furthermore, we aimed to elucidate the association between causative foods and sensitized pollens in patients with OAS due to plant-derived foods.
Methods: SPTs and specific IgE measurements (CAP-FEIA: CAP) were performed in relation to foods and pollens in 118 patients with positive histories of OAS due to plant-derived foods. Patients with positive histories and with positive skin test responses were identified as having type I allergy to the causative foods.
Results: The mean age of 63 patients with positive histories and positive skin test responses was 29.2 years (range, 2-61 years), and there were twice as many females as male. The most frequent causative foods were found to be apple, peach, kiwi, and melon in 13, 12, 12, and 11 patients, respectively. CAP frequency was shown to be similar to that of SPT regarding apple, whereas it was less than that of SPT regarding melon, peach, and kiwi. A significant correlation between the frequencies of SPT and CAP was found regarding apple (r=0.39, p<0.05) but not peach, kiwi, and melon. Forty-one of 63 patients with OAS (66.1%) had pollinosis and/or allergic rhinitis. In patients with OAS due to apple, the positive ratio of CAP response against alder pollen was higher than that in patients with OAS due to melon. In patients with OAS due to melon, the positive ratio of CAP responses against ragweed pollen, grass pollen, and mugwort pollen was higher than that in patients with OAS due to apple.
Conclusion: In this study, positive ratios of SPT and CAP tended to differ according to the causative food, showing a smaller potential for reaction than might be suggested by patient history. Therefore, for the time being it would be more accurate to use a skin test for the diagnosis of OAS due to plant-derived foods.