Anaphylaxis to pine nuts and immunological cross-reactivity with pine pollen proteins.

Despite the wide use of pine nuts, the fruit of Pinus pinea, only a few reports of allergic reactions to them have been published. We present herein a case of food allergy to pine nuts in a patient who showed no clinical symptoms to pine pollen despite the presence in her serum of specific IgE antibodies. In order to verify whether the reaction against pine nuts was IgE mediated, specific IgE against pine nuts and pollen were evaluated by skin-prick test, prick by prick and RAST. Immunoblotting and immunoblotting-inhibition were used to evaluate the allergenic components of both extracts and their cross-reactivity. Prick by prick with fresh pine nuts and RAST with pine nut and pine pollen extracts showed that the patient had high levels of specific IgE against both extracts. Immunoblotting experiments showed the presence in serum of IgE antibodies against several components in pine nuts and pollen. Immunoblotting-inhibition experiments demonstrated the presence of some cross-reacting components. These data confirm the existence of food allergy induced by pine nuts. This sensitization to pine nuts developed with no symptoms of pine pollinosis. Development of pollinosis may require a longer time of exposure to allergens. Based on the cross-reactivity between pine nut and pine pollen extracts, cosensitization to these two allergens could be possible.     

Latex and chickpea (Cicer arietinum) allergy: first description of a new association

In this paper we describe the existence of cross-reactivity between allergens from latex and chickpea, a food from the Leguminosae family, which is common in the Mediterranean diet. We present the case report of a spina bifida boy with a clinical relevant food allergy to chickpea (oral syndrome + dysphonia), developing after the appearance of latex allergy symptoms (lip angioedema + intraoperative anaphylaxis). Specific IgE to latex and chickpea was demonstrated by skin prick tests, measurement of patient's serum specific IgE and IgE-immunoblotting. Cross-reactivity was studied by means of EAST-inhibition and western blotting-inhibition. A strong inhibition was observed in several IgE-binding bands when latex extract was used in solid phase and patient serum was preincubated with chickpea extract (chickpea extract as inhibitor phase). As far as we know, this is the first report of cross-reactivity between latex and chickpea, a food which should therefore be added to the extensive list of latex cross-reactive foods.     

Allergy to Salsola Kali in a Salsola Incanescens-rich Area: Role of Extensive Cross Allergenicity

BackgroundPollens from the Salsola spp. are an important source of respiratory allergy in tropical countries. Our aim was to characterize the IgE binding proteins of S. incanescens pollen extract and study its cross-reactivity with S. kali pollen allergens.MethodsPrick tests with S. kali and S. incanescens pollen extracts were performed on eight respiratory allergy patients from Mashhad, Northeast Iran. The antigenic profiles and IgE-binding patterns of S. kali and S. incanescens pollen extracts were compared by SDS-PAGE and Western blotting, using individual sera from the salsola pollen-sensitive patients. Cross-reactivity of proteins in the two weeds was assessed by IgE- immunoblotting inhibition.ResultsS. kali and S. incanescens pollen extracts showed similar IgE-binding profiles in Western blotting. The IgE binding components of 39, 45, 66 and 85 kDa were detected in both pollen extracts. Furthermore, inhibition of the immunoblots revealed extensive inhibition of IgE binding to proteins and a close relationship between these two weeds allergens.ConclusionsS. incanescens pollen is a potent allergen source with several IgE binding components that shows a close allergenic relationship with S. kali. Our results suggest that in S. incanescens-rich areas, S. kali pollen extracts could be used as a diagnostic reagent for allergic patients to S. incanescens pollen.     

Cross-reactivity between Parietaria species using the major rParj1 and rParj2 allergens.

Parietaria pollen is one of the most important outdoor allergenic sources in all the Mediterranean countries, with a large number of subjects showing a positive skin prick test to both P. judaica and P. officinalis pollen extracts. A cross-reactivity between the two species has been already reported although few data are known at the molecular level. Twenty-five consecutive patients with Parietaria pollen allergy were selected on the basis of their clinical history. Skin prick test to P. judaica and officinalis extracts was performed. In vitro IgE measurement to both allergenic sources was performed by using a quantitative assay. ELISA inhibition experiments were made by using the rParj1 and rParj2 allergens. All the patients showed a positive skin prick test to both Parietaria species. Quantitative IgE measurement showed similar antibody concentration for P. judaica and P. officinalis extracts. ELISA inhibition experiments demonstrated that the cross-reactivity between the two species was due to the presence of the Parj1 and Parj2 allergens in the extracts with a high conserved IgE epitopes content. We conclude that P. judaica and P. officinalis pollens contain highly cross-reactive species-specific major allergens useful for the diagnosis and therapy of both allergenic sources.     

变态反应性疾病变应原的体内外诊断及分析

目的 应用变应原皮肤点刺试验(SPT)分析西安地区不同变态反应性疾病的主要变应原,同时应用UniCAP 100检泓血清特异性免疫球蛋白E(IgE),并对结果进一步评价.方法 我院变态反应门诊就诊的变态反应性疾病患者679例,选用19种常见的变应原进行SPT,比较不同疾病患者主要变应原阳性率的异同;其中116例患者同时抽取静脉血检测血清粉尘螨特异性IgE,并与SPT结果比较.结果 ①在所有变态反应性疾病患者中,粉尘螨、屋尘螨均是最主要的变应原,总的阳性率分别是49.78%和43.00%,其次依次为蒿属花粉、霉菌、悬铃木属花粉和树Ⅰ花粉等,总阳性率均在10%以上,上述变应原是西安地区变态反应性疾病的主要变应原;②羽毛、鸡蛋、牛奶、蒿属、虾和花生6种变应原的阳性率在4种变态反应性疾病组间比较差异有统计学意义(P<0.05),其余变应原的阳性率在各组间差异无统计学意义,哮喘及过敏性鼻炎组患者的主要变应原以吸入性变应原为主,而荨麻疹组及过敏性紫癜组患者的主要变应原除以上吸入变应原外,还包括鸡蛋、牛奶、虾和花生等食人性变应原;③以血清特异性IgE为标准,以"+++及以上"为SPT阳性标准时的诊断价值高于以"++及以上"为SPT阳性标准,且IgE定量与SPT风团直径呈对数关系(r=0.629,P<0.05).结论 粉尘螨、屋尘螨、蒿属花粉、霉菌、悬铃木属花粉和树Ⅰ花粉等变应原是西安地区变态反应性疾病的主要变应原;不同疾病的主要变应原稍有不同;IgE定量与SPT风团直径呈对数关系,两者检测结果可以互补.     

Microarray based IgE detection in poly-sensitized allergic patients with suspected food allergy - an approach in four clinical cases

BackgroundComponent-resolved diagnosis and microarray technology have been recently introduced into clinical allergy practice, and may be particularly useful in poly-sensitized allergic patients.MethodsWe compare the clinical usefulness of a microarray-based IgE detection assay (ISAC^®) with skin tests and specific IgE with standard allergens (sIgE) or their monocomponents in four case reports of patients poly-sensitized to aeroallergens and food.ResultsCase 1: a woman with rhinitis, oral allergy syndrome to several fruits and anaphylaxis to cherry. Diagnostic tests supported non-specific lipid transfer proteins (nsLTPs) primary sensitization.Case 2: a woman with exercise-induced asthma, rhino-conjunctivitis and oral allergy syndrome to fresh fruits of different families. A diagnosis of primary grass and weed pollen allergy with profilin and pathogenesis-related protein family 10 (PR-10) cross-reactive food allergy was proposed.Case 3: a man with atopic eczema, asthma, rhinitis, and multiple anaphylactic episodes with cashew nuts and oral allergy syndrome to fruits. The diagnostic workup supported a primary birch pollen allergy with PR-10 and nsLTPs cross-reactive food allergy.Case 4: a woman with rhino-conjunctivitis, per-operative anaphylaxis due to latex and recent pharyngeal angio-oedema episodes. The diagnosis was a primary grass and weed pollen allergy with equivocal profilin sensitization and no obvious cross-reactivity mediated by nsLTPs sensitization.ConclusionsThe possibility to carry out multiple sIgE measurements with single protein allergens, in particular with the microarray technique, is a useful, simple and non-invasive diagnostic tool in complex poly-sensitized allergic patients.     

Allergy to cassava: a new allergenic food with cross-reactivity to latex.

Patients who are allergic to latex (Hevea brasiliensis) may exhibit cross-hypersensitivity with foods. We present a case of anaphylaxis due to cassava in a patient suffering from pollinosis, latex allergy, and latex-fruit syndrome. We performed sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting with cassava, avocado, chestnut, banana, kiwi, and latex extracts in order to analyze the protein bands and their molecular weights, and identify immunoglobulin (Ig) E-binding bands. Immunoblot inhibition and enzyme-linked immunosorbent assay (ELISA) inhibition were performed with latex in order to assess cross-reactivity. Cassava exhibited numerous protein bands, 5 of which were IgE-binding (89.75, 46.28, 26.68, 21.38, and 19.49 kd). These cassava IgE-binding bands were 100% inhibited by preincubation of the patient's serum with latex extract. The ELISA inhibition between latex and cassava was 23%. Our results confirm cassava as another food with clinical cross-reactivity in patients suffering from latex allergy.     

Profilin sensitisation in a Mediterranean population

BackgroundSensitisation to pan-allergens has become an interesting tool for the study of the allergenic profile of different populations. Profilins are one of the most common pan-allergens to be studied because they are responsible for a large number of sensitisations and are clearly related to cross-reactivity and co-sensitisation.ObjectivesThe objective of this study was to investigate the profile of sensitisation to profilins and to correlate it with sensitisation to foods and pollens.MethodsSix hundred and fifty-four consecutive patients were skin-prick tested with a battery of common allergens including pollens, epithelia, mites and moulds and profilin and divided into three groups depending on their sensitisation profile (non-atopic, atopic with pollinosis and atopic without pollinosis). Patients with symptoms were challenged and diagnosed with the offending food extracts. Profilin sensitisation was identified and analysed in detail.ResultsAccording to the classification of the population, the prevalence of profilin sensitisation was estimated at 2.9% in patients suffering respiratory allergy, 4.2% in atopic patients, and 5.9% in pollen-sensitised individuals. Positive association was observed between pollen (except Cupressus and olive) and profilin but not with moulds, mites or epithelia. With respect to foods, positive association was only observed between profilin and melon sensitisation. Lastly, in terms of symptoms, positive association was only observed between profilin sensitisation and OAS.ConclusionProfilin sensitisation seems to be a marker of pollen-related poly-sensitisation in our area. Pan-allergen diagnosis seems to be an essential tool for developing and improving selection of the correct treatment for allergic patients.     

Identification of peroxidase-1 and beta-glucosidase as cross-reactive wheat allergens in grass pollen-related wheat allergy

BackgroundSome patients with wheat-dependent exercise-induced anaphylaxis (WDEIA) or wheat allergy showed negative ω-5 gliadin-specific IgE test and high level of grass pollen-specific IgE. It was presumed that these patients developed allergic reaction upon cross-reaction of their IgE antibodies raised against grass pollen allergens to wheat allergens. This study aimed to clarify clinical characteristics and wheat allergens of this phenotype of WDEIA/wheat allergy, which were tentatively diagnosed as grass pollen-related wheat allergy (GPWA).MethodsA total of six patients with GPWA were enrolled, and controls were 17 patients with grass pollen allergy but no episode of wheat allergy, and 29 patients with other wheat allergies: 18 with conventional WDEIA and 11 with hydrolyzed wheat protein allergy. Sensitization to wheat proteins was determined by basophil activation test (BAT). IgE-binding proteins in wheat flour were identified by immunoblotting followed by mass spectrometry. Wheat allergen-specific IgE tests were established by CAP-FEIA system.ResultsAll the six patients with GPWA were sensitized to water-soluble wheat proteins in BAT and IgE-immunoblotting, and peroxidase-1 (35 kDa) and beta-glucosidase (60 kDa) were identified as specific IgE-binding wheat proteins. The binding of patient IgE to these proteins was inhibited by pre-incubation of patient sera with grass pollen. The peroxidase-1- and beta-glucosidase-specific IgE tests identified three and four of six patients with GPWA, respectively, but only two of 29 controls, indicating high specificity of these tests.ConclusionsPeroxidase-1 and beta-glucosidase are specific wheat allergens for GPWA among grass pollen allergy and other types of wheat-induced food allergies.     

Cross-reactivity between fruit and vegetables

Vegetable foods are the most frequent cause of food allergy after the age of 5 years. The most commonly implicated foods are fruit and dried fruits, followed in Spain by legumes and fresh garden produce. In patients allergic to fruit and garden produce, multiple sensitizations to other vegetable products, whether from the same family or taxonomically unrelated, are frequent, although they do not always share the same clinical expression. Furthermore, more than 75 % of these patients are allergic to pollen, the type of pollen varying in relation to the aerobiology of the area. The basis of these associations among vegetable foods and with pollens lies in the existence of IgE antibodies against "panallergens", which determines cross-reactivity. Panallergens are proteins that are spread throughout the vegetable kingdom and are implicated in important biological functions (generally defense) and consequently their sequences and structures are highly conserved. The three best-known groups are allergens homologous to Bet v 1, profilins, and lipid transfer proteins (LTP). Allergens homologous to Bet v 1 (major birch pollen allergen) constitute a group of defense proteins (PR-10), with a molecular weight of 17 kDa, which behave as major allergens in patients from northern and central Europe with allergy to vegetables associated with birch pollen allergy. In these patients, the primary sensitization seems to be produced through the inhalation route on exposure to birch pollen. The symptomatology characteristically associated with sensitization to this family of allergens is oral allergy syndrome (OAS). Profilins are highly conserved proteins in all eukaryotic organisms and are present in pollen and a wide variety of vegetable foods. They have a molecular weight of 14 kDa and present a high degree of structural homology as well as marked cross-reactivity among one another. The presence of anti-profilin IgE broadens the spectrum of sensitizations to vegetable foods detected through skin tests and/or in vitro tests but whether it correlates with the clinical expression of food allergy is unclear.LTPs are the most commonly implicated allergens in allergy to Rosaceae fruits in patients from the Mediterranean area without birch pollen sensitization. LTPs are a family of 9kDA polypeptides, widely found in the vegetable kingdom and implicated in cuticle formation and defense against pathogens (PR-14). They are thermostable and resistant to pepsin digestion, which makes them potent food allergens and explains the frequent development of systemic symptoms (urticaria, anaphylaxis) in patients allergic to Rosaceae fruits in Spain. LTPs have also been identified in other vegetable foods and in pollens and a marked degree of cross-reactivity among them has been demonstrated, which may explain (together with profilin) the frequency of individuals sensitized to vegetable foods in the Mediterranean area.     

Anaphylaxis to pine nut: cross-reactivity to Artemisia vulgaris?

The use of pine nuts, the seeds of Pinus pinea, is on the increasing in the modern Mediterranean diet. Little more than 20 cases of allergy to this tree nut have been published, and cross-reactivity with pine pollen, peanut and almond has already been reported. We describe the case of a young boy with several episodes of anaphylaxis after pine nut ingestion. Specific IgE to pine nut and Artemisia vulgaris was demonstrated by skin prick tests and in vitro determination of specific IgE, although no IgE to pine pollen or other nuts was detected. Immunoblotting of Artemisia vulgaris and pine nut revealed two matching diffuse bands, just below 14 kDa and 30 kDa. The ImmunoCAP inhibition assays showed complete inhibition of pine nut specific IgE after serum incubation with Artemisia vulgaris extract. As far as we know, this is the first reported case of documented cross-reactivity between pine nut and Artemisia vulgaris.     

Further characterization of IgE-binding antigens in kiwi, with particular emphasis on glycoprotein allergens.

Fruit allergy is frequently associated with birch pollinosis. The aim of this study was to investigate which kiwi allergens were involved in subjects allergic to fruit alone and in patients allergic to both fruit and birch pollen. Sera of nine patients (five with both kiwi and birch pollen allergy and four with isolated kiwi allergy) were studied by immunoblot of kiwi extract. Eight of the nine sera reacted with the 30 kDa protein. Furthermore, IgE-binding proteins were seen at approximately 23 kDa (detected by five sera), 43 kDa and 80 kDa (four sera), and > 80 kDa (two sera). One serum showed no IgE binding to any kiwi allergen. The 30 kDa is the major allergen in kiwi and was purified by anion-exchange chromatography and characterized by isoelectrofocusing and amino acid sequencing. The comparison of its partial amino acid sequence with data from the Swiss Protein Bank revealed that this protein is actinidine. The carbohydrate structures in kiwi and birch pollen extracts were investigated with seven lectins. On kiwi blot, Aleuria aurantia agglutinin showed strong reactivity (indicating fucose residues) to the components of 35 to 92 kDa, while concanavalin A (indicating mannose, glucose or N-acetylglucosamine residues) showed weak binding at 67 kDa. In contrast, strong binding of Galanthus nivalis agglutinin (indicating mannose residues) and concanavalin A was found on birch pollen blots. The presence of IgE against carbohydrate structures was determined by means of enzyme-linked immunosorbent assay (ELISA) after periodate treatment of kiwi extract. The IgE binding was reduced by periodate treatment of kiwi coated microtiter plates, but not by sera reacting exclusively with the 30 kDa protein. Furthermore, selected sera were treated with proteinase K-digested kiwi and birch pollen extracts as the sources of crossreactive carbohydrate determinants. In accordance with the results of sodium periodate treatment, significant levels of anti-cross-reactive carbohydrate determinant IgE were found in sera from patients allergic to both kiwi and birch pollen. Our results show that the major allergen for kiwi allergy is the 30 kDa protein and additionally that the cross-reaction between kiwi and birch pollen allergy is mainly due to carbohydrate moieties.     

Cross-Reactivity of Peanut Allergens

Peanut seeds are currently widely used as source of human food ingredients in the United States of America and in European countries due to their high quality protein and oil content. This article describes the classification and molecular biology of peanut seed allergens with particular reference to their cross-reactivities. Currently, the IUIS allergen nomenclature subcommittee accepts 12 peanut allergens. Two allergens belong to the cupin and four to the prolamin superfamily, and six are distributed among profilins, Bet v 1-like proteins, oleosins, and defensins. Clinical observations frequently report an association of peanut allergy with allergies to legumes, tree nuts, seeds, fruits and pollen. Molecular cross-reactivity has been described between members of the Bet v 1-like proteins, the non-specific lipid transfer proteins, and the profilins. This review also addresses the less well-studied cross-reactivity between cupin and prolamin allergens of peanuts and of other plant food sources and the recently discovered cross-reactivity between peanut allergens of unrelated protein families.     

Allergy to laxative compound (Plantago ovata seed) among health care professionals.

BACKGROUND: The seeds of Plantago ovata (psyllium, ispaghula) used in the manufacture of bulk laxatives are known to be the cause of occupational allergy (rhinitis, asthma) in health care and pharmaceutical workers. OBJECTIVE: We studied the prevalence of P ovata seed allergy among health care workers in geriatric care homes and compared it with a group of health care professionals not exposed to P ovata seed. Cross reactivity with Plantago lanceolata pollen was also studied. METHODS: Two groups of health professionals were recruited: 58 health care workers from geriatric care homes who were exposed daily to laxatives containing P ovata and 63 nonexposed health care professionals. The prevalence of allergy and sensitization to P ovata seed was determined based on clinical history, skin prick test, and analysis of specific immunoglobulin (Ig) E. IgE immunoblotting was performed to calculate the molecular weights of the P ovata seed allergens. Cross reactivity to P lanceolata pollen was studied by enzyme allergosorbent test (EAST) and immunoblot inhibition techniques. RESULTS: The prevalence of sensitization and clinical allergy to P ovata seed in the exposed group was 13.8% and 8.6%, respectively. No sensitization was observed in the nonexposed group. IgE-binding proteins of 17, 20, 25, 32-34, 54, 73-77, and > 97 kDa were identified. EAST inhibition and immunoblot inhibition demonstrated the existence of cross reactivity between P ovata seed and P lanceolata pollen extracts. CONCLUSIONS: The rate of sensitization to P ovata seed is high among health care workers in geriatric care homes (13.8%). A mild cross reactivity between P ovata seed and P lanceolata pollen was observed.     

Components of plant-derived food allergens: Structure,diagnostics, and immunotherapy

A large number of plant-derived food allergen components have been identified to date. Although these allergens are diverse, they often share common structural features such as numerous disulfide bonds or oligomeric structures. Furthermore, some plant-derived food allergen components cross-react with pollen allergens. Since the relationship between allergen components and clinical symptoms has been well characterized, measurements of specific IgE to these components have become useful for the accurate clinical diagnosis and selection of optimal treatment methods for various allergy-related conditions including allergy caused by plant-derived foods. Herein, I have described the types and structures of different plant allergen components and outlined the diagnosis as well as treatment strategies, including those reported recently, for such substances. Furthermore, I have also highlighted the contribution of allergen components to this field.     

Prevalence of IgE antibodies to an extract from rubber tree (Hevea brasiliensis) latex and recombinant pollen allergens (Phl P 1, Phl P 2, Phl P 5, Bet v 1 and Bet v 2) in the sera of Italian atopic patients

BackgroundPrevious studies have reported cross-reactivity between latex and grass allergens. Inhibition studies have indicated cross-reactivity of IgE with latex and grass pollen proteins. A panel consisting of a few recombinant allergens, namely rPhI p 1, rPhl p 2, rPhl p 5 and profilin, was sufficient to diagnose grass pollen allergy in patients allergic to grass pollen.MethodsSerum samples from 528 consecutive outpatients with IgE antibodies towards at least one allergen (IgE level > 0.35 kAU/L) were selected for this retrospective study. Total and specific serum IgE to rPhl p 1, rPhl p 2, rPhl p 5, rBet v 1, rBet v 2, latex, birch, hazel, mugwort, wall pellitory, Dermatophagoides pteronissinus, Alternaria tenuis, cat and apple were measured by the immunoenzymatic capsulated hydrophilic carrier polymer (CAP) FEIA system (Pharmacia & Upjohn).ResultsOf 123 polysensitized patients with antilatex Ig1E, 12 (9.76%) had symptoms after latex exposure. Ten of 12 subjects monosensitized to latex had symptoms after latex exposure. Symptomatic patients had higher IgE levels to latex than symptomless patients (P = 0.046). A higher prevalence of antilatex IgE was seen in sera containing specific IgE to rPhl p 1, rPhl p 5 and rBet v 2. A good correlation (Spearman's r = 0.52; P = 0.001) between high levels of antilatex IgE and total serum IgE was found.ConclusionsThe findings of the present study may support the concept that a high proportion of sera containing IgE to rBet v 2, rPhl p 1 and rPhl p 5 simultaneously contain antilatex IgE. Therefore, patients with specific IgE to these recombinant allergens with no history of current latex exposure may need additional evaluation.     

Immunoglobulin-E Reactivity to a Glycosylated Food Allergen (Peanuts) Due to Interference With Cross-Reactive Carbohydrate Determinants in Heavy Drinkers

Background: N‐glycans in plant and invertebrate glycoproteins can induce extensive IgE cross‐reactivity therefore limiting the specificity of in vitro allergy tests. IgE sensitization to N‐glycans (cross‐reactive carbohydrate determinants, CCDs) may be increased in heavy drinkers, who therefore show IgE reactivity to aeroallergens, latex, and Hymenoptera venoms. The peanut, a CCD‐bearing allergen, is the leading cause of severe food allergic reactions in many populations. Aim of the study: To investigate the potential interference of CCDs with determinations of IgE to peanuts in heavy drinkers. Methods: We determined IgE to peanuts and IgE to a CCD marker (MUXF³, the N‐glycan from bromelain) in 41 heavy drinkers admitted to the hospital and 54 healthy controls. None of the participants reported symptoms of peanut allergy. In cases with positive (≥0.35 kU/l) IgE to peanuts, we performed inhibition assays with a neoglycoprotein consisting of MUXF³ molecules coupled to bovine serum albumin (MUXF³‐BSA) and a similar neoglycoprotein lacking xylose and fucose (MM‐BSA). In the same cases, we screened for IgE to a panel of recombinant nonglycosylated peanut allergens. SDS‐PAGE immunoblotting and inhibition assays were performed in selected cases. Results: The prevalence of positive IgE to peanuts was 22 and 3.7% in heavy drinkers and healthy controls, respectively (p < 0.001). Peanut‐IgE positivity was closely related to the presence of IgE to CCDs. In most (8/9) heavy drinkers with positive IgE to peanuts, reactivity was inhibited by preincubation with MUXF³‐BSA, but not with MM‐BSA. IgE binding to multiple bands on immunoblotting studies was also inhibited by MUXF³‐BSA preincubation. IgE to nonglycosylated recombinant peanut allergens was uniformly negative. Conclusion: Heavy drinking is associated with clinically asymptomatic IgE reactivity to peanuts, a relevant food allergen, in relation to CCD interference.     

Allergènes alimentaires croisant avec les allergènes des pollens

The range of pollen-food cross-reactions has increased over the past decade, the clinical pictures are more clear with respect to the allergens concerned, and the molecular basis for some of them have been determined. Diagnostic methods include skin tests, assays for specific IgE, and open and double blind oral provocation tests. Investigation of allergic cross-reactions, first based solely on immunological inhibition techniques using natural allergen extracts, have benefited from molecular biology. Many allergens homologous with pollen allergens have been sequenced and the three dimensional structure of Pru av 1 has been determined, allowing studies on a sub-molecular scale. Allergen cross-reactions between pollen and food, for which the clinical relevance is well established, involve allergens of the Bet v 1 and Bet v 2 families. These allergens are present in numerous edible fruits and vegetables. Identity with the Bet v 1 sequence varies from 38 to 67%, being closest for the profilins (70-80%). Cross sensitization with Bet v 1 and profilins, although particularly frequent, may be silent clinically. Other candidate molecules involved in cross-reactions between pollen and food allergens are Bet v 6, a minor birch allergen, the lipotransferases found in some of the compositae, and the 1,3-β-glucanases corresponding to a major olive allergen. The significance of the detection of specific IgE directed against carbohydrate determinants remains to be investigated. A major problem for the clinician is the absence of clinical significance of cross-reactivity that has been demonstrated in vitro and in vivo.     

The Role of Lipid Transfer Proteins in Allergic Diseases

Nonspecific lipid transfer proteins (LTPs) are important allergens in fruits, vegetables, nuts, pollen, and latex. Despite their wide distribution throughout the plant kingdom, their clinical relevance is largely confined to the Mediterranean area. As they can sensitize via the gastrointestinal tract, LPTs are considered true food allergens, and IgE reactivity to LTPs is often associated with severe systemic symptoms. Although Pru p 3 represents the predominant LTP in terms of patients’ IgE recognition, the contribution of pollen LTPs in primary sensitization cannot be ruled out. Due to structural homology, LTPs from different allergen sources are generally IgE cross-reactive. However, sensitization profiles among allergic patients are extremely heterogeneous, and individual cross-reactivity patterns can be restricted to a single LTP or encompass many different LTPs. Molecule-based approaches in allergy research and diagnosis are important for better understanding of LTP allergy and could assist clinicians with providing adequate patient-tailored advice.     

Identification of a New Allergen from Amaranthus retroflexus Pollen,Ama r 2

BackgroundPollinosis from Amaranthus retroflexus pollen is a common cause of respiratory allergy in Iran with a high positive rate (68.8%) among Iranian allergic patients. The aim of the present study was to evaluate the allergenicity of the A. retroflexus pollen profilin.MethodsUsing sera from twelve patients allergic to A. retroflexus pollen, IgE-binding proteins from the A. retroflexus pollen extract was identified by immunoblotting. The cDNA of A. retroflexus pollen profilin was amplified, then cloned into the pET-21b (+) vector, expressed in Escherichia coli, and finally purified by metal affinity chromatography. The IgE-binding capacity of the recombinant protein was then analyzed by the ELISA, immunoblotting, and inhibition assays, as well as by the skin prick test (SPT).ResultsImmunoblotting results indicated a 14.6 kDa protein with IgE-reactivity to 33% (4/12) among A. retroflexus pollen-allergic patients. Nucleotide sequencing of the cDNA revealed an open reading frame of 399 bp encoding for 133 amino acid residues which was belonged to the profilin family and designated as Ama r 2. A recombinant Ama r 2 (rAma r 2) was then produced in E. coli as a soluble protein which showed a strong IgEreactivity via ELISA confirmed by the SPT. Inhibition experiments revealed high IgE cross-reactivities with the profilins from other plants.ConclusionsThe profilin from the A. retroflexus pollen, Ama r 2, was firstly identified as an allergen. Moreover, rAma r 2 was produced in E. coli as a soluble immunoreactive protein with an IgE-reactivity similar to that of its natural counterpart.