Food-dependent exercise-induced allergic reactions in Lipid Transfer Protein (LTP) hypersensitive subjects: new data and a critical reappraisal.

Lipid transfer protein is the main cause of both primary food allergy and food-dependent exercise-induced allergic reactions (FDEIAR) in Italy. What characterizes LTP-hypersensitive patients with FDEIAR is still unclear. We investigated the key characteristics of LTP-hypersensitive patients with or without FDEIAR in a large cohort of individuals sensitized to this allergen. 1,203 food-allergic patients, diagnosed on the basis of unequivocal clinical history and presence of circulating food allergen-specific IgE were studied. Serum IgE reactivity was assessed using the Allergen ExplorerALEX system (Macroarray Diagnostics, Vienna, Austria). Association of specific IgE reactivities with FDEIAR was investigated, and patients with and without FDEIAR sensitized to LTP were compared. 116 subjects (9.6%) had FDEIAR. Among these, 77 (66.3%) were LTP-reactors and 16 (13.8%) were sensitized to Tri a 19 (omega-5-gliadin). Different LTPs and omega-5-gliadin emerged as the sole allergens clearly associated with FDEIAR. Severity of allergic reactions was paralleled the level of specific IgE to LTPs. Patients with FDEIAR showed significantly lower IgE levels than their counterparts with food allergy at rest, and displayed nearly identical IgE levels regardless of the severity of allergic reactions induced by exercise. FDEIAR are associated with specific allergens. Specific IgE levels in LTP-hypersensitive patients with FDEIAR show an intermediate titer between those simply sensitized and those showing classic food allergy.