Identification of potential allergens involved in systemic reactions to melon and watermelon

Fruit allergy and anaphylaxis in children: Culprit fruits and clinical findings

Background: Fruit allergy usually presents with mild-to-moderate symptoms but serious systemic reactions, e.g., anaphylaxis, may also occur. Objective: This study aimed to examine the clinical and laboratory characteristics of patients with fruit allergy and fruit-induced anaphylaxis. Methods: Patients diagnosed with fruit allergy at Dışkapı Hematology and Oncology Hospital and Bilkent City Hospital between January 2017 and January 2023 were included in the study. The diagnosis of anaphylaxis was made according to the European Allergy and Clinical Immunology Anaphylaxis Guideline. Results: During the study period, skin-prick tests with food allergens were performed on 9432 patients in our clinic, and fruit allergy was detected in 78 patients (0.82%). Five patients with inaccessible medical records were excluded from the study. 40 (54.8%) were boys. The median (interquartile range) age at the onset of symptoms was 72 months (12.5-144 months). Sixty-eight of the patients (93.2%) had a concomitant allergic disease, the most common of which was allergic rhinitis (n = 48 [65.8%]). The 73 patients had a history of reaction to 126 fruits. Twenty-five patients (19.8%) were allergic to multiple fruits. The most common fruit allergen was banana (22/126 [17.4%]), followed by peach (18/126 [14.2%]) and kiwi (17/126 [13.5%]). Mucocutaneous findings were observed most frequently after fruit consumption (120/126 [95.2%]). Anaphylaxis occurred in 17 patients (23.2%) with 21 fruits.The fruits most commonly associated with anaphylaxis were banana (6/21 [28.6%]) and kiwi (6/21 [28.6%]). Conclusion: Fruit allergy generally presents with mild symptoms, e.g., oral allergy syndrome, but severe systemic symptoms, e.g., anaphylaxis, can also be observed. Kiwi and banana are the fruits that most commonly cause anaphylaxis. Although more comprehensive studies are needed to comment on the development of tolerance, especially in patients with anaphylaxis, responsible fruit avoidance is still the most important strategy.

Recurrent Anaphylaxis with Watermelon and Pumpkin Seeds in a Boy Tolerant to Their Pulps

Background: Seeds are widely consumed as a traditional snack and have rich contents beneficial to health. With an increase in consumption rates, allergic reactions occur more frequently. We focus on multiple seed consumption related to recurrent anaphylaxis in this case. Case Presentation: We evaluated an 11-year-old boy with recurrent anaphylaxis. According to his medical records, he had been hospitalized several times, diagnosed with anaphylaxis, and treated. The family noticed direct (eating) or indirect contact with pumpkin seeds. In addition, the family mentioned another anaphylactic episode after watermelon seed and poppy seed bread consumption. We conducted skin prick-to-prick tests, examined total immunoglobulin E levels, and prescribed the treatment with an adrenalin autoinjector and preventive dietary recommendations. Conclusion: Anaphylaxis, particularly recurrent ones, should be evaluated with detailed anamnesis and supported with laboratory tests. Although seeds are beneficial and highly nutritious, it is necessary to consider them a source of allergens.

Are Dietary Lectins Relevant Allergens in Plant Food Allergy?

Lectins or carbohydrate-binding proteins are widely distributed in seeds and vegetative parts of edible plant species. A few lectins from different fruits and vegetables have been identified as potential food allergens, including wheat agglutinin, hevein (Hev b 6.02) from the rubber tree and chitinases containing a hevein domain from different fruits and vegetables. However, other well-known lectins from legumes have been demonstrated to behave as potential food allergens taking into account their ability to specifically bind IgE from allergic patients, trigger the degranulation of sensitized basophils, and to elicit interleukin secretion in sensitized people. These allergens include members from the different families of higher plant lectins, including legume lectins, type II ribosome-inactivating proteins (RIP-II), wheat germ agglutinin (WGA), jacalin-related lectins, GNA (Galanthus nivalis agglutinin)-like lectins, and Nictaba-related lectins. Most of these potentially active lectin allergens belong to the group of seed storage proteins (legume lectins), pathogenesis-related protein family PR-3 comprising hevein and class I, II, IV, V, VI, and VII chitinases containing a hevein domain, and type II ribosome-inactivating proteins containing a ricin B-chain domain (RIP-II). In the present review, we present an exhaustive survey of both the structural organization and structural features responsible for the allergenic potency of lectins, with special reference to lectins from dietary plant species/tissues consumed in Western countries.