Lipid transfer proteins: the most frequent sensitizer in Italian subjects with food-dependent exercise-induced anaphylaxis
Prof. Antonino Romano, Unità di Allergologia, Complesso Integrato Columbus, Via G. Moscati 31, 00168 Rome, Italy.
Specific food-dependent exercise-induced anaphylaxis (S-FDEIAn) is a distinct form of food allergy in which symptoms are elicited by exercise performed after ingesting food to which the patient has become sensitised. Non-specific FDEIAn (NS-FDEIAn) is a syndrome provoked by exercise performed after ingesting any food.
We sought to identify the culprit allergenic molecules in patients with FDEIAn, combining ‘classic’ allergy testing with an allergenic molecule-based microarray approach for IgE detection.
All subjects were evaluated who reported at least one episode of anaphylaxis in association with physical exercise performed within 4 h after a meal. We performed skin prick tests (SPT) with commercial food extracts, prick plus prick tests (P + P) with fresh foods (P + P), and serum specific IgE assays by means of both the ImmunoCAP (CAP) and the ISAC 89 microarray system (ISAC).
Among our 82 FDEIAn patients, the most frequent suspected foods were tomato, cereals, and peanut. SPT, P + P, and CAP displayed different degrees of sensitivity. Each test disclosed some positivities not discovered by others. Seventy-nine subjects were positive to at least one food (49 to more than 20), whereas three were negative. All suspected foods were positive to at least one of SPT, P + P, and CAP. When tested using the ISAC, 64 (78%) subjects were positive to Pru p 3 [peach lipid transfer protein (LTP)], 13 were positive to other food allergen molecules, and five displayed negative results to all food allergenic molecules. Overall, 79 patients probably had S-FDEIAn and the other 3 NS-FDEIAn.
Multiple food hypersensitivity represents a clinical hallmark of a large percentage of FDEIAn patients. The very high prevalence of IgE to the LTP suggests a role of this allergen group in causing S-FDEIAn.