Allergy to eggplant (Solanum melongena) caused by a putative secondary metabolite.

We describe a case of allergy caused by ingestion of eggplant in an atopic subject. Symptoms included urticaria, itching of the throat, and hoarseness. Skin prick test (SPT) was positive with 4 varieties of eggplant; however, allergen-specific immunoglobulin E was not detected. SPT with fractions of green long eggplant extract obtained by dialysis and ultrafiltration suggested the allergen to be less than 10 kd. SPT following acetone precipitation of eggplant extract revealed that the allergen was present in the supernatant portion. Further analysis by size-exclusion chromatography of the 10 kd filtrate of eggplant extract on Sephadex G-25 followed by SPT of fractions revealed that the causative allergen was a low molecular weight nonprotein secondary metabolite of less than 1 kd. To our knowledge, this is the first report of allergy to the ingestion of eggplant in which a nonprotein secondary metabolite has been detected as an allergen.