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Background: Allergy to sharon fruit (persimmon) has been only rarely reported. Cross-reactivity with pollen (profilin and Bet v 6) appeared to be involved, but Bet v 1 has not been implicated previously. Objective: It is our aim to identify whether Bet v 1 sensitization is linked to sharon fruit allergy. Methods: Two patients with a reaction upon first exposure to sharon fruit were included in the study, as well as 7 patients with birch-pollen-related apple allergy. Sensitivity was assessed by skin prick testing (SPT), a radio-allergosorbent test (RAST) and immunoblotting. RAST analysis was performed for Bet v 1, Bet v 2 and Bet v 6. Cross-reactivity was evaluated by RAST and immunoblot inhibitions. Biological activity of IgE was measured by basophil histamine release. Sharon fruit allergy was evaluated by double-blind placebo-controlled food challenge (DBPCFC) or open challenge (OC). Results: Both sharon-fruit-allergic patients demonstrated positive reactions in the RAST (8.6 and 6.2 IU/ml, respectively) and SPT (wheal area 37 and 36 mm2). Sharon fruit allergy was confirmed by DBPCFC in 1 patient. The second patient refused a challenge because of the severe initial reaction. Sera from both patients were reactive to Bet v 1 and Bet v 6, which was cross-reactive with sharon fruit by inhibition assays. The patient with the severest reactions was reactive to profilin on immunoblotting. However, profilin did not induce significant histamine release, nor did Bet v 6. Bet v 1 induce approximately 60% histamine release. An OC with sharon fruit in 7 patients allergic to birch pollen and apple, who had not eaten sharon fruit previously, was positive in 6/7 cases. Conclusions: Birch-pollen-related allergy to sharon fruit is mediated by the known cross-reactive pollen allergens including Bet v 1 and may become more of a problem should sharon fruit consumption increase. Copyright © 2005 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Abstract Background Mal d 1 is a major apple allergen causing food allergic symptoms of the oral allergy syndrome (OAS) in birch-pollen sensitised patients. The Mal d 1 gene family is known to have at least 7 intron-containing and 11 intronless members that have been mapped in clusters on three linkage groups. In this study, the allelic diversity of the seven intron-containing Mal d 1 genes was assessed among a set of apple cultivars by sequencing or indirectly through pedigree genotyping. Protein variant constitutions were subsequently compared with Skin Prick Test (SPT) responses to study the association of deduced protein variants with allergenicity in a set of 14 cultivars. Results From the seven intron-containing Mal d 1 genes investigated, Mal d 1.01 and Mal d 1.02 were highly conserved, as nine out of ten cultivars coded for the same protein variant, while only one cultivar coded for a second variant. Mal d 1.04, Mal d 1.05 and Mal d 1.06 A, B and C were more variable, coding for three to six different protein variants. Comparison of Mal d 1 allelic composition between the high-allergenic cultivar Golden Delicious and the low-allergenic cultivars Santana and Priscilla, which are linked in pedigree, showed an association between the protein variants coded by the Mal d 1.04 and -1.06A genes (both located on linkage group 16) with allergenicity. This association was confirmed in 10 other cultivars. In addition, Mal d 1.06A allele dosage effects associated with the degree of allergenicity based on prick to prick testing. Conversely, no associations were observed for the protein variants coded by the Mal d 1.01 (on linkage group 13), -1.02, -1.06B, -1.06C genes (all on linkage group 16), nor by the Mal d 1.05 gene (on linkage group 6). Conclusion Protein variant compositions of Mal d 1.04 and -1.06A and, in case of Mal d 1.06A, allele doses are associated with the differences in allergenicity among fourteen apple cultivars. This information indicates the involvement of qualitative as well as quantitative factors in allergenicity and warrants further research in the relative importance of quantitative and qualitative aspects of Mal d 1 gene expression on allergenicity. Results from this study have implications for medical diagnostics, immunotherapy, clinical research and breeding schemes for new hypo-allergenic cultivars.

Background: Allergy to a plant food can either result from direct sensitization to that food or from primary sensitization to pollen, latex, or another food., Objective: We sought to investigate the primary sensitizers in apple allergy across Europe, the individual allergens involved, and whether these differences determine the clinical presentation., Methods: Patients (n = 389) with positive case histories and skin prick test responses to fresh apple were selected in the Netherlands, Austria, Italy, and Spain. Skin prick tests and RASTs to a panel of pollens and plant foods were performed, as well as RASTs to Bet v 1 and the apple allergens Mal d 1, 2, 3, and 4., Results: In the Netherlands, Austria, and Italy apple allergy is mild (>90% isolated oral symptoms) and related to birch pollinosis and sensitization to Bet v 1 and its apple homologue, Mal d 1, which has an odds ratio of local reactions of 2.85 (95% CI, 1.47-5.55). In Spain apple allergy is severe (>35% systemic reactions) and related to peach allergy and sensitization to Mal d 3 (nonspecific lipid transfer protein), which has an odds ratio of systemic reactions of 7.76 (95% CI, 3.87-15.56)., Conclusion: The analysis of individual apple allergens in a clinical context has provided insight into the sensitization pathway and into the intrinsic risk an allergen bears to induce mild or severe food allergy., Clinical Implications: Information on the sensitization pathway is essential to develop preventive strategies in food allergy. The application of individual food allergens with a known intrinsic risk will improve the prognostic value of diagnostic tests.

Background: Individual amino acid residues of the major birch pollen allergen, Bet v 1, have been identified to be crucial for IgE recognition. The objective of the present study was to evaluate whether this concept was applicable for the Bet v 1-homologous apple allergen, Mal d 1., Methods: A Mal d 1 five-point mutant was produced by PCR techniques, cloned into pMW 172 and expressed in Escherichia coli BL21(DE3) cells. To evaluate the allergenic properties of the engineered protein compared to Mal d 1 wild-type IgE immunoblotting, ELISA, peripheral blood monocytes proliferation assays, and skin prick tests were performed., Results: The Mal d 1 mutant showed reduced capacity to bind specific IgE as compared to wild-ype Mal d 1 in in vitro assays in the majority of the sera tested. In ELISA, 10 out of 14 serum samples displayed an 88-30% decrease in IgE binding to Mal d 1 mutant compared to wild-type Mal d 1. Skin prick tests in apple-allergic patients (n = 2) confirmed the markedly decreased ability of the Mal d 1 mutant to induce allergic reactions in vivo. However, the relevant T cell epitopes were present in the mutated molecule according to peripheral blood mononuclear cell proliferation assays., Conclusions: Our findings suggest that it is possible to modulate the IgE-binding properties of allergens by single amino acid substitutions at crucial positions which might be useful for future immunotherapy of birch-pollen-associated food allergies which are not ameliorated by birch pollen immunotherapy., ((c) 2006 S. Karger AG, Basel)

Background: Pepsin resistance of allergens like lipid transfer protein and 2S albumin has been suggested as explanation for the severity of symptoms often induced by these allergens. Component-resolved diagnosis with purified labile and stable allergens has therefore been proposed to better characterize the risk involved in a positive in vitro IgE test. However, for many foods, purified allergens are not (yet) available., Objective: It was the aim of this study to evaluate the potential of pepsin-digested whole-food extracts to distinguish between IgE responses to stable (potentially severe) and labile (mild) allergens., Methods: Sera (n = 143) from Italian, Spanish and Dutch patients with hazelnut and/or apple ingestion-related symptoms were analyzed for residual IgE binding to pepsin-resistant hazelnut and/or apple allergens. Control and pepsin-digested hazelnut and apple extracts were used for radioallergosorbent test analysis and immunoblot analysis., Results: Pepsin digestion of food extracts, like from hazelnut and apple used for in vitro diagnostic tests, provides a way to distinguish sensitization to pepsin-resistant allergens from that to pepsin-susceptible allergens. In this selected group of patients, IgE reactivity to pepsin-digested extracts correlated with sensitization to the stable allergen lipid transfer protein. The analysis further revealed that the use of soluble pepsin can result in false-positive in vitro tests (2/143)., Conclusion: Pepsin-digested food extracts are a convenient tool to identify patients with IgE antibodies against potentially dangerous stable allergens, in particular for those foods where the relevant stable allergens have not yet been identified. This can increase the clinical prognostic value of food allergy serology., (Copyright (c) 2005 S. Karger AG, Basel.)