Laurian Zuidmeer

The prevalence of plant food allergies: A systematic review

BACKGROUND There is uncertainty regarding the prevalence of allergies to plant food. OBJECTIVE To assess the prevalence of allergies to plant food according to the different subjective and objective assessment methods. METHODS Our systematic search of population-based studies (since 1990) in the literature database MEDLINE focused on fruits, vegetables/legumes, tree nuts, wheat, soy, cereals, and seeds. Prevalence estimates were categorized by food item and method used (food challenges, skin prick test, serum IgE, parent/self-reported symptoms), complemented by appropriate meta-analyses. RESULTS We included 36 studies with data from a total of over 250,000 children and adults. Only 6 studies included food challenge tests with prevalences ranging from 0.1% to 4.3% each for fruits and tree nuts, 0.1% to 1.4% for vegetables, and < 1% each for wheat, soy, and sesame. The prevalence of sensitization against any specific plant food item assessed by skin prick test was usually < 1%, whereas sensitization assessed by IgE against wheat ranged as high as 3.6% and against soy as high as 2.9%. For fruit and vegetables, prevalences based on perception were generally higher than those based on sensitization, but for wheat and soy in adults, sensitization was higher. Meta-analyses showed significant heterogeneity between studies regardless of food item or age group. CONCLUSION Population-based prevalence estimates for allergies to plant products determined by the diagnostic gold standard are scarce. There was considerable heterogeneity in the prevalence estimates of sensitization or perceived allergic reactions to plant food.

Efficacy of birch-pollen immunotherapy on cross-reactive food allergy confirmed by skin tests and double-blind food challenges

Background The effect of birch‐pollen immunotherapy (IT) on cross‐reactive food allergies is controversial.

Lipid transfer protein allergy: primary food allergy or pollen/food syndrome in some cases.

Purpose of review To summarize recent findings on non-specific lipid transfer proteins in food allergy, with a specific focus on the localization, stability and route of sensitization. Recent findings Plant non-specific lipid transfer proteins are major food allergens, especially in the Mediterranean area. They have been identified as allergens in a number of foods and the list grows ever longer. As non-specific lipid transfer proteins are considered to be ‘true’ food allergens that sensitize directly via the gastrointestinal tract their stability during food processing and gastric digestion has been studied in more detail. In addition, several groups have tried to determine the sensitization patterns of lipid transfer protein-reactive patients, to determine and possibly clarify the observed geographical differences in sensitization. Different sensitization routes (via the respiratory tract or even transdermally) have been suggested. Summary As the structure and molecular properties of non-specific lipid transfer proteins are resolved and more purified non-specific lipid transfer proteins become available for diagnostic purposes, detailed studies on the sensitization pattern and route are becoming feasible. Continuing studies on the pattern of lipid transfer protein sensitization will give more insight into the development and possible treatment of lipid transfer protein-related food allergy.

The prevalence and distribution of food sensitization in European adults.

Complaints of ‘food allergy’ are increasing. Standardized surveys of IgE sensitization to foods are still uncommon and multicountry surveys are rare. We have assessed IgE sensitization to food‐associated allergens in different regions of Europe using a common protocol.

Evaluation by double-blind placebo-controlled oral challenge of the clinical relevance of IgE antibodies against plant glycans

Background:  The clinical relevance of immunoglobulin E (IgE) to plant glycans is a longstanding debate. We sought to evaluate their clinical reactivity using the human glycoprotein lactoferrin expressed in rice.

Peanut-specific IgE antibodies in asymptomatic Ghanaian children possibly caused by carbohydrate determinant cross-reactivity

Background The prevalence of peanut allergy has increased in developed countries, but little is known about developing countries with high peanut consumption and widespread parasitic infections. Objective We sought to investigate peanut allergy in Ghana. Methods In a cross-sectional survey among Ghanaian schoolchildren (n = 1604), data were collected on reported adverse reactions to peanut, peanut sensitization (serum specific IgE and skin reactivity), consumption patterns, and parasitic infections. In a subset (n = 43) IgE against Ara h 1, 2, 3, and 9 as well as cross-reactive carbohydrate determinants (CCDs) was measured by using ImmunoCAP. Cross-reactivity and biological activity were investigated by means of ImmunoCAP inhibition and basophil histamine release, respectively. Results Adverse reactions to peanut were reported in 1.5%, skin prick test reactivity in 2.0%, and IgE sensitization (≥0.35 kU/L) in 17.5% of participants. Moreover, 92.4% of those IgE sensitized to peanut (≥0.35 kU/L) had negative peanut skin prick test responses. Schistosoma haematobium infection was positively associated with IgE sensitization (adjusted odds ratio, 2.29; 95% CI, 1.37-3.86). In the subset IgE titers to Ara h 1, 2, 3, and 9 were low (<1.3 kU/L), except for 6 moderately strong reactions to Ara h 9. IgE against peanut was strongly correlated with IgE against CCDs (r = 0.89, P < .0001) and could be almost completely inhibited by CCDs, as well as S haematobium soluble egg antigen. Moreover, IgE to peanut showed poor biological activity. Conclusions Parasite-induced IgE against CCDs might account largely for high IgE levels to peanut in our study population of Ghanaian schoolchildren. No evidence of IgE-mediated peanut allergy was found.

The role of profilin and lipid transfer protein in strawberry allergy in the Mediterranean area

Background In contrast to other Rosaceae fruit, only few cases of patients with adverse reactions to strawberry are listed in literature.

Severe immediate allergic reactions to grapes: Part of a lipid transfer protein-associated clinical syndrome

Background: Grape allergy is considered rare; grape lipid transfer protein (LTP; Vit v 1), an endochitinase and a thaumatin-like protein (TLP) have been reported as grape allergens. A considerable number of patients have referred to our department for severe reactions to grapes, and several IgE binding proteins were detected. Objectives: The aim of this study was to identify and characterise the allergens involved in severe allergic reactions to grapes and describe the population in which they occur. Methods: Patients with reported severe allergic reactions to grapes (n = 37) are described. Grape allergens were purified/fractionated by a combination of chromatographic techniques, identified by proteomic analysis and biochemically characterised. Immunoreactivity was assessed by blot (inhibitions) and RAST (inhibitions), and skin prick tests were performed with the isolated allergens. Results: All subjects were polyallergic, sensitised and reactive to several additional foods and pollen. All patients were sensitised to grape LTP. A 28-kDa expansin, a 37.5-kDa polygalacturonase-inhibiting protein, a 39-kDa β-1,3-glucanase and a 60-kDa protein were identified as minor grape allergens. Endochitinase and TLP did not play a role. Inhibition experiments revealed the possible cross-reactive role of LTP for clinical sensitivities to other LTP-containing plant foods, but also the involvement of cross-reactive carbohydrate determinants of minor allergens in IgE cross-reactivity. Conclusions: LTP is the major grape allergen, while additional minor allergens may contribute to clinical reactivity. Severe grape allergy presents in atopic patients who frequently react to other LTP-containing, plant-derived foods. The ‘LTP syndrome’ is the appropriate term to describe this condition.

Lipid Transfer Proteins from Fruit: Cloning, Expression and Quantification

Background: Lipid transfer proteins (LTP) are stable, potentially life-threatening allergens in fruits and many other vegetable foods. The aim of this study was to clone and express recombinant apple LTP (Mal d 3), as has previously been done for peach LTP (Pru p 3) and set up quantitative tests for measuring fruit LTPs. Methods: cDNA for Mal d 3 and Pru p 3 was cloned, expressed in the yeast Pichia pastoris and the resulting proteins were purified via cation exchange chromatography. The immune reactivity of rMal d 3 was compared to nMal d 3 by RAST (inhibition), immunoblotting and basophil histamine release testing. To obtain monoclonal and monospecific polyclonal antibodies, mice and rabbits were immunized with purified nMal d 3. Results: The deduced amino acid sequence of Mal d 3 was identical to the published sequence, Pru p 3 differed at two positions (S9A and S76H). The rMal d 3 had an IgE-binding potency and biological activity close to its natural counterpart. One sandwich ELISA selectively detecting apple LTP and another cross-reactive with cherry, nectarine and hazelnut LTP were developed. In addition, a competitive RIA was developed with polyclonal rabbit antiserum and labeled nMal d 3. Conclusion: rMal d 3 (as shown before for rPru p 3) may be a useful tool for application in component-resolved diagnosis of food allergy. Assays for the measurement of LTP will increase the traceability of this potentially dangerous allergen.

A mutant of the major apple allergen, Mal d 1, demonstrating hypo-allergenicity in the target organ by double-blind placebo-controlled food challenge.

Background Allergen‐specific immunotherapy for food allergy has been hindered by severe side‐effects in the past. Well‐characterized hypo‐allergenic recombinant food allergens potentially offer a safe solution.