Rice allergy demonstrated by double-blind placebo-controlled food challenge in peach-allergic patients is related to lipid transfer protein reactivity.

BACKGROUND: The risk factors for sensitisation to rice and the involved allergens are still partially unknown. In this study we evaluated the clinically relevant aspects of rice allergy in DBPCF-positive patients, the major rice allergens, the severity of peach- and rice-induced symptoms in respect to Pru p 3 sensitisation and the role of anti-rPru p 3 IgE levels as a risk factor for rice allergy. METHODS: In 148 peach-allergic subjects, patients with allergic reactions to rice and rice-positive serum IgE were selected. Symptoms were verified by double-blind placebo-controlled food challenges (DBPCFCs), performed at a maximum dosage of 25 g. Rice allergens, identified by IgE immunoblotting, were characterised by N-terminal amino acid sequencing. The relationship between anti-rPru p 3, 1 and 4 IgE levels and rice symptoms were statistically analysed. RESULTS: Eight out of 10 recruited rice-allergic patients had positive DBPCFCs, while 2 patients were not challenged due to their previously documented severe reactions. All patients with rice-induced symptoms were Pru p 3 positive and presented with higher anti-rPru p 3 levels than the rice-sensitised but tolerant patients. A 9-kDa lipid transfer protein, which was highly homologous to Pru p 3, was identified as the major rice allergen and elicited a positive response in all of the patients. Five patients reacted to a putative 15- to 17-kDa rice allergenic protein, and 3 patients reacted to an [alpha]-amylase/subtilisin inhibitor that was approximately 20 kDa. CONCLUSION: Rarely, allergic reactions to rice can arise in patients with peach allergies who are sensitised to Pru p 3, particularly in patients with high anti-rPru p 3 IgE levels.

Tomato allergy: detection of IgE-binding lipid transfer proteins in tomato derivatives and in fresh tomato peel, pulp, and seeds.

There is an increasing consumption of tomatoes worldwide: fresh in salads, cooked in household sauces, or industrially processed. Although many tomato allergens have been identified, there is no information in the literature on the allergenic components found in commercial tomato products. The primary aim of the study was to evaluate the allergenic profile of commercial tomato products by skin prick tests (SPTs) and IgE/immunoblotting in tomato-allergic subjects. The secondary end point was the study of the IgE-binding profile of tomato peel, pulp, and seeds. Forty tomato-allergic patients, reporting oral allergy syndrome (OAS) at different grades of severity for fresh and, in some cases, also for cooked tomato, were selected on the basis of positive tomato allergy history or open food challenge (OFC). They were evaluated by SPTs with different experimental tomato extracts. SDS-PAGE/immunoblotting was performed to detect tomato allergens, which were then identified by Edman degradation. Twenty-three patients (57.5%) presented first-grade OAS at the OFC, whereas 17 (42.5%) reported severe symptoms. Ten of these 17 patients (25%) reported allergic reactions to cooked tomatoes; in immunoblotting tests, their sera reacted only to lipid transfer protein (LTP). In commercial products, LTP was the only detectable allergen. In contrast to other LTP-containing fruits, in tomato, an IgE-binding LTP was identified not only in the peel but also in the pulp and seeds. This study demonstrates that, in fresh tomato, different LTP isoforms are present and allergenic. Industrial tomato derivatives still contain LTP, thus presenting a problem for LTP-allergic patients.