Date Published: April 03, 2017
Publisher: John Wiley and Sons Inc.
Author(s): N. Mothes‐Luksch, M. Raith, G. Stingl, M. Focke‐Tejkl, E. Razzazi‐Fazeli, R. Zieglmayer, S. Wöhrl, I. Swoboda.
In the Mediterranean area, lipid transfer proteins (LTPs) are important causes of plant‐food allergies often associated with severe allergic reactions. There, peach LTP (Pru p 3) seems to be the primary sensitizer, whereas in Central Europe, little is known about the importance of LTP sensitization. In this region, allergen extract‐based diagnosis is often complicated by co‐sensitization to Bet v 1, the major birch pollen allergen, its cross‐reactive food allergens, and profilins. We investigated the role of LTP sensitization in Central European patients displaying strong allergic reactions to plant‐derived food. Analysis of IgE reactivity revealed that ten of thirteen patients were sensitized to Pru p 3, nine to Bet v 1, and two to profilin. Our results showed that LTP sensitization represents a risk factor for severe allergic symptoms in Central Europe. Furthermore, the strong IgE reactivity detected in immunoblots of plant‐food extracts indicated that Pru p 3 can be used as a marker allergen for LTP sensitization also in Central European patients.
Nonspecific lipid transfer proteins (nsLTPs) are extremely stable, structurally highly conserved plant defense proteins, present throughout the whole plant kingdom.1, 2, 3 LTPs have also been identified as important, cross‐reactive plant‐food allergens in fruits, vegetables, nuts, and cereals (reviewed in 4 and 5). Sensitization to LTPs is known to occur frequently in individuals living in the Mediterranean area, where it is often associated with severe, sometimes life‐threatening reactions.5, 6, 7, 8 Peach LTP (Pru p 3) represents the molecule that dominates the immune response to LTPs in these countries and is regarded as a marker for severe systemic reactions to plant‐derived food.5 Awareness of LTP sensitization is also increasing in Northern and Central Europe.9, 10, 11, 12 There, diagnosis of LTP sensitization using plant extracts is difficult due to a frequent co‐sensitization to birch pollen allergens, especially the major birch pollen allergen Bet v 1, Bet v 1 cross‐reactive food allergens, and profilins, all heat labile proteins, known as inducers of mild clinical manifestations.5 We therefore investigated whether LTPs also play a major role in Central European patients with severe reactions to plant‐derived foods and whether Pru p 3 can also serve as a diagnostic cross‐reactive marker allergen in patients in this region.
Thirteen Austrian patients with a clinical history of either severe anaphylactic reactions to plant‐food material or strong SPT reactions of ≥8 mm wheal diameter13 to a broad range of plant material were selected (Table S1). Ethical approval and written consent were obtained from the Austrian ethics committee (EK Nr: 1052/2013). Skin tests and determination of total and allergen‐specific IgE were carried out as described in Methods S1 and S2.
The patients enrolled in this study either experienced severe reactions upon ingestion of plant‐derived food or showed strong reactivity to various plant extracts in skin prick tests (for details, see Table S1). To assess the patients’ reactivity profiles by single component‐resolved diagnosis (CRD), specific IgEs to rPru p 3, rBet v 1, and rPhl p 12 (the profilin from Phleum pratense) were determined by ImmunoCAP, ImmunoCAP ISAC, and/or ELISA. Interestingly, ten of the patients had IgE antibodies to Pru p 3 (76.9%), nine (69.2%) to Bet v 1, and only two (15.4%) to profilin (Table 1). These findings are consistent with the high prevalence of birch pollinosis in Central Europe, but they further indicate that LTPs might also cause severe symptoms in Central European population. The importance of CRD for determination of plant‐derived food allergy is underlined by our finding that the majority of the Pru p 3‐positive patients were also positive for Bet v 1 (60%), and consistent with the recommendations of the EAACI for food allergy and anaphylaxis.18
We have established that nsLTPs play an important role as plant‐food allergens in a Central European population reacting with strong symptoms. Patients from the central and northern parts of Europe, where primary sensitization to Bet v 1 usually occurs via the respiratory tract, often present only with mild symptoms after consumption of plant‐food material. In these subjects, plant‐derived food allergy is mediated by Bet v 1‐related proteins causing allergic cross‐reactions due to the high sequence similarity with Bet v 1. In contrast, allergic reactions to plant‐derived food in Southern Europe are usually associated with systemic reactions, due to a primary sensitization to LTPs, very potent allergens, usually causing severe reactions.
The authors declare no conflict of interests regarding the publication of this article.
N. Mothes‐Luksch, M. Raith, G. Stingl, S. Wöhrl, and I. Swoboda designed the research. N. Mothes‐Luksch, M. Raith, M. Focke‐Tejkl, E. Razzazi‐Fazeli, and R. Zieglmayer performed the experiments. N. Mothes‐Luksch, M. Raith, S. Wöhrl, and I. Swoboda wrote the manuscript. All authors read and approved the final manuscript.