Identification of a thaumatin-like protein as a new allergen in persimmon (Diospyros kaki) with cross-reactivity with banana (Musa acuminata) / Identificação de uma proteína semelhante à taumatina como um novo alérgeno no caqui (Diospyros kaki) com reatividade cruzada com a banana (Musa acuminata)

Allergy to persimmon (Diospyros kaki ) has been only rarely reported. The antigenic composition of the fruit is not entirely known. Thaumatin-like proteins (TLPs) have been described as allergens in pollens and various fruits, such as kiwi and banana, but not in persimmon. We report the case of a 22-year-old man, with persistent moderate-to-severe allergic rhinitis, sensitized to house dust mites. The patient describes an episode of oral mucosa and ear canal pruritus, followed by diffuse urticaria, which rapidly evolved to dysphonia, dyspnea, and dizziness, after eating raw persimmon. A few months later he developed similar cutaneous symptoms accompanied by nausea, vomiting, abdominal colic, and hypotension immediately after the intake of banana. The prick-prick test with raw persimmon and banana were positive, as well as the serum specific IgE to the extract of these fruits. The ImmunoCAP ISAC_112i test demonstrated a positive specific IgE against Act d 2 (kiwi thaumatin), which is homologous to banana TLP (Mus a 4). Serum IgE inhibition test with "sponge" of Diospyros kaki ImmunoCAP (f301) showed partial inhibition (40%) of IgE to Act d 2. This raises the suspicion that a TLP is at least partially responsible for the referred sensitization. This patient is sensitized to Diospyros kaki and Musa acuminata. An anaphylactic reaction to consumed persimmon, presumably as a result from cross-allergy with banana thaumatin was diagnosed in our patient. Thaumatin has not been previously described as an allergen of persimmon with cross-reactivity with banana, and in vitro with Act d 2 (kiwi TLP).

A alergia ao caqui (Diospyros kaki ) tem sido raramente documentada, não sendo a composição antigênica da fruta totalmente conhecida. Proteínas semelhantes à taumatina (TLPs) foram descritas como alergênicos em pólens e várias frutas, como no kiwi e banana, mas não no caqui. Apresenta-se o caso de um doente de 22 anos, com rinite alérgica persistente moderadagrave, sensibilizado a ácaros do pó doméstico. O doente refere episódio de prurido na mucosa oral e canal auditivo, seguido de urticária generalizada, que rapidamente evoluiu para disfonia, dispneia e tontura, após ingestão de caqui. Poucos meses depois, desenvolveu sintomas cutâneos semelhantes, acompanhados de náuseas, vómitos, cólica abdominal e hipotensão imediatamente após ingestão de uma banana. O teste cutâneo por picada com caqui e banana em natureza foram positivos, bem como o doseamento de IgE específica. O teste ImmunoCAP ISAC_112i identificou a presença de IgE específica para Act d 2 (taumatina do kiwi), homóloga da TLP da banana (Mus a 4). O estudo de inibição ImmunoCAP ISAC com "esponja" de Diospyros kaki (f301) produziu uma inibição parcial (40%) da ligação de IgE a Act d 2, permitindo presumir que uma proteína semelhante à taumatina é, pelo menos, parcialmente responsável pela referida sensibilização. Este doente encontra-se sensibilizado a Diospyros kaki e Musa acuminata. Uma anafilaxia ao caqui ingerido, presumivelmente resultante de reatividade cruzada com a taumatina da banana foi diagnosticada. Não estão descritas na literatura TLPs como alergênicos do caqui com reatividade cruzada com a banana e com Act d 2 in vitro (TLP do kiwi).

Frozen fruit skin prick test for the diagnosis of fruit allergy.

Background: Diagnosis of fruit sensitisation by skin prick test (SPT) is fast and easy to perform. Nevertheless, some fruit is not available throughout the year. Freezing aliquots of these fresh fruits to be defrosted would be a good solution to perform SPT at any time. Objective: To compare the reproducibility of SPT with Rosaceae and Cucurbitaceae frozen fruit with fresh and commercial fruit extracts. Methods: SPT with the following fruit were performed: apricot, cherry, strawberry, nectarine, Japanese medlar, peach, (peel and pulp), yellow and red plum, melon and watermelon. We compared fresh fruit, commercial extract and fruit which had been frozen at -18°C. Results were read by planimetry (Inmunotek prick-filmTM) after 15 minutes. Results: The study group comprised 48 patients (9 males, 39 females) with a mean age of 31, 6 ± 2,0 years. Concordance of positive and negative results was extremely high and significant in all cases. Correlation between frozen fruit and commercial extract, frozen fruit and fresh and commercial extract and fresh fruit was statistically significant in all cases except for strawberry. Conclusions: The use of frozen fruit is a valid method, as the performance of the SPT is similar to that of fresh fruit. This enables diagnostic procedures with seasonal fruit at any time of the year.