Tomato Allergy: Detection of IgE-Binding Lipid Transfer Proteins in Tomato Derivatives and in Fresh Tomato Peel, Pulp, and Seeds

Abstract

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.

Expression and characterization of a new isoform of the 9 kDa allergenic lipid transfer protein from tomato (variety San Marzano)

“…The analysis was carried out on single-strand cDNA synthesized on RNA extracted from San Marzano tomato fruits, starting with the oligo-dT primer. RNA was purified from complete fruit since the presence of allergenic LTPs in tomato pulp has also been reported (Pravettoni et al, 2009). Double-stranded cDNA molecules were obtained by PCR using oligonucleotides TomSM-22_F (or TomSM-21_F) and the anchor primer (AP).…”

“…Indeed, the Sola I 3 allergen is reported as corresponding to an LTP protein (P93224) for which allergenicity has not been investigated (Plant et al, 1991). Allergenicity of other tomato 9 kDa LTP isoforms from different tomato varieties, has been verified (Bencivenni et al, 2014;Le et al, 2006;Pravettoni et al, 2009), but sequence and structural data are still missing.…”

A survey of plants responsible for causing allergic contact dermatitis in the Amathole District, Eastern Cape, South Africa

“…The common observation that some people exhibit allergic symptoms to raw tomato is important to the food industry considering the increasing consumption of raw tomatoes in salads worldwide. Ten out of 17 patients (25%) reported allergic reactions to cooked tomatoes; in immunoblotting tests, their sera reacted only to lipid transfer protein (LTP) (Pravettoni et al, 2009). In fresh tomato, different LTP isoforms are present and allergenic.…”

The Role of Lipid Transfer Proteins in Allergic Diseases

“…In fact, it was shown that LTPs retain their allergenic activity during processing; thus, even cooked food, fruit juices, jams, and fermented drinks still display IgE-binding activity [22••]. It is noteworthy that LTPs were the only detectable allergens in different commercial tomato products [45]. In addition, several studies have demonstrated the resistance of LTPs to proteolysis by pepsin [22••], while gastric and duodenal digestion was assessed in detail for Vit v 1 [46].…”