Clinico-Immunological Analysis of Eggplant (Solanum melongena) Allergy Indicates Preponderance of Allergens in the Peel

BACKGROUND: Eggplant (Solanum melongena L.) is known to cause food allergy in some Asian countries but detailed studies on eggplant allergy are lacking. OBJECTIVE: The objective is to investigate sensitization to different parts of eggplant fruit, and detection of the allergens. METHODS: Six eggplant-allergic subjects were assessed for sensitization to eggplant (peel/pulp, and raw/cooked) by skin prick test, allergen-specific IgE, and immunoblots. Allergens were analyzed for glycoprotein nature by staining/lectinoblots, and in vitro stability in simulated gastric fluid. RESULTS: All the eggplant-sensitized subjects showed positive skin prick test with peel, pulp, raw, and cooked eggplant extracts; allergen-specific IgE to all these was positive. Raw eggplant contains 5 allergens in the range 36-71 kD. Most allergens are localized in the eggplant peel (9 allergens; 26-71 kD range) than the pulp (3 allergens; 52-71 kD); among these, the 26, 28, 36, and 71 kD allergens seem to be heat-stable. The 43, 45, 64, and 71 kD allergens are detected as glycoproteins; the 26, 64, and 71 kD allergens are stable displaying retention of IgE-binding ability in simulated gastric fluid digestion. CONCLUSIONS: Eggplant is a multiallergenic vegetable in the context of presence of allergens in all edible parts of eggplant having preponderance in the peel.