Litchi is a food which may result in allergy symptoms in sensitised individuals.

Litchi Allergy Test: Allergen Exposure

Litchi originates in southern China where it thrives along riverbanks and in coastal areas, and China remains the world’s largest producer of the fruit, although it has since spread to other parts of Asia and the Americas. It is technically a nut, most closely related to walnut, cashew and pistachio.

Litchi fruit is covered by a leathery rind, which is pink to strawberry-red in colour and rough in texture. The fruit is oval, heart-shaped or nearly round, growing to 2.5 to 5 cm in length and from 7 to 12 cm in diameter. The rind is easily separated from the flesh. The edible portion is white to translucent, firm and juicy. The flavour is sweet and fragrant. Inside the fruit is a single seed that can vary considerably in size.

Litchis can be eaten fresh, or added to fruit cups and fruit salads. They can also serve as garnishes, hors d’oeuvres, and ingredients in a variety of desserts, including sherbet

Being low in phenols and non-astringent in all stages of maturity, litchis are canned with the addition of tartaric or citric acid to prevent browning. They are also occasionally spiced, pickled, or made into sauces, syrups, jams, jellies or wine. The flesh of dried litchis is eaten like raisins. Litchis can also be frozen, but after thawing they spoil quickly. In China, honey from hives near litchi groves is prized.

Litchis and their seeds, peel, root, bark and flowers, are used in traditional medicine to treat coughing and other throat ailments, intestinal complaints, neuralgia, and tumours. However, traditional Chinese medicine advises that excessive consumption of raw litchis causes fever and nosebleed.

Litchi Allergy Test: Allergen Description

Several allergens present in litchi have been characterised including a profilin, an isoflavone reductase and a triose-phosphate isomerase (a major allergen).

Among 7 litchi varieties, no significant differences in allergenicity have been demonstrated. Significant differences in allergens were detected between the peel and flesh of the litchi.

The pericarp showed a higher allergenic activity. The allergens were shown to be very heat-stable and unaltered by freezing or canning for 12 months.

Litchi Allergy Test: Potential Cross-Reactivity

An extensive cross-reactivity among the different individual species of the family (litchi, ackee fruit, longan and rambutan) could be expected but has not been documented.

Broad cross-reactivity between litchi fruit and other plants has been reported, and profilin has been identified as the protein responsible. In addition, a high degree of cross-reactivity between litchi profilin and birch profilin was found.

The presence of an isoflavone reductase panallergen may result in cross-reactivity between this fruit and other plants containing this allergen, e.g. birch pollen, mango, apple, pear, orange, banana and carrot.

Litchi Allergy Test: Clinical Experience

Litchi may induce symptoms of food allergy, including anaphylaxis, in sensitised individuals.

Other reported symptoms include swelling of the lips, swelling of the oral mucosa, pruritus, generalised urticaria and dyspnoea. Food-dependent exercise-induced anaphylaxis associated with litchi has been reported. Cross-reactivity between litchi, Artemisia pollen and sunflower seed has been suggested. Also, cross-reactivity of litchi with latex has been demonstrated through inhibition experiments.