IgE-mediated reactions
Litchi may induce symptoms of food allergy, including anaphylaxis, in sensitised individuals. (4, 16, 17, 18 19, 20) As exotic fruits enter new Western markets, the prevalence of allergy to this fruit is bound to increase, as demonstrated by a study of 38 litchi-allergic patients. (1)
A 12-year-old girl developed swelling of the lips, pruritus, generalised urticaria and dyspnoea 30 minutes after eating a raw litchi. A second event occurred 10 minutes after eating a piece of cake covered with a fruit cocktail, resulting in generalised urticaria and pruritis, rhinoconjunctivitis and dyspnoea. Restlessness, flush, generalised urticaria and inspiratory stridor occurred 50 minutes after eating half a litchi. Skin-specific IgE was detected to raw litchi, and a cellular allergen stimulation test was positive, but specific IgE in serum was – surprisingly – negative to litchi but positive to latex. Cross-reactivity of litchi to latex was shown by inhibition studies. (14)
Anaphylaxis to litchi (2, 4, 18, 19) has been described in a number of reports, including one of a 23-year-old woman with inhalant allergy to pollen from plants of the Compositae family, who experienced an acute episode of severe dyspnoea after eating 2 to 3 fresh litchis. She felt an itching in her mouth and throat a few minutes after eating the fruit. Five minutes later her lips and throat swelled, and she experienced severe dyspnoea. Skin-specific IgE to fresh and tinned litchi (pasteurised at 90 degrees C for 10 to 15 minutes) was found. Serum-specific IgE to litchi was detected. (4) Anaphylaxis was reported in a 21-year-old woman, who developed urticaria, angioedema, swelling of the oral mucosa, and dyspnoea within 10 minutes of eating Litchi on an empty stomach, although she had eaten this fruit many times previously without adverse effects. Skin-specific IgE testing with the fresh fruit and rind was positive. A double-blind oral challenge resulted in urticaria. (18)
A 26-year-old man developed pruritus, generalised urticaria, and severe angioedema of his lips and tongue, followed by dyspnoea, within 15 minutes of ingesting a litchi. Litchi -specific IgE antibodies were not detected, but a basophil activation test (BAT) and a cellular antigen stimulation test (CAST) to litchi were both positive, as was a prick-to-prick test with fresh litchi. The individual also experienced oral allergy syndrome to parsley and was sensitised to mugwort but not to latex or profilin. The authors suggested that mugwort was the allergen responsible for the cross-reactivity, as no sensitisation to latex or profilin could be demonstrated. (19)
A report described 2 patients who developed anaphylaxis after ingesting litchi for the first time. Both had been previously diagnosed with respiratory allergy to Compositae pollen and food allergy to sunflower seed. Both were prick-to-prick test-positive for litchi fruit, Artemisia pollen, sunflower seed, pistachio nut and other pollens. Serum IgE was detected for litchi in 1 individual (0.45 kU/1). Cellular stimulation tests for litchi were positive in both, as well as for Artemisia pollen and sunflower seed. Protein bands in the 24-70 kDa range were isolated in the 3 extracts, with a common 70 kDa recognised in both patients’ serum. (2)
A 33-year-old non-atopic woman was described with multiple episodes of anaphylaxis after ingestion of apple, banana and litchi, fruits belonging to botanically disparate plant families. Five years previously, minutes after eating an apple, she had become breathless and developed widespread wheals, followed by respiratory arrest. Two years later, a similar but milder reaction occurred after she ate a banana, which resulted in extensive whealing, dyspnoea and tongue oedema, but no respiratory arrest. She avoided all fruits for the next 3 years, during which time she was symptom-free. A few months before being investigated, she ate litchi, which resulted in severe urticaria, angioedema of the eyelids and mild wheezing. Prick testing was positive for apple and banana. No obvious cross-reactive mechanisms appeared to be playing a role. (20)
Food-dependent exercise-induced anaphylaxis associated with litchi has been reported. (21)
Contact urticaria was described in a 34-year-old woman, who developed generalised urticaria and angioedema, associated with bronchospasm, shortly after eating litchi. Skin-specific IgE was detected using a scratch test with litchi extract. (22)