House dust mite allergy and shrimp allergy: a complex interaction.

Summary: Background and Objective. Sensitization and allergy to shrimp among Italian house dust mite allergic patients are not well defined and were investigated in a large multicenter study. Methods. Shrimp sensitization and allergy were assessed in 526 house dust mite (HDM)-allergic patients submitted to the detection of IgE to Der p 10 and 100 atopic control not sensitized to HDM. Results. Shrimp allergy occurred in 9% of patients (vs 0% of 100 atopic controls not sensitized to HDM; p minor 0.001). Shrimp-allergic patients were less frequently hypersensitive to airborne allergens other than HDM than crustacean-tolerant subjects (35% vs 58.8%; p minor 0.005). Only 51% of tropomyosin-sensitized patients had shrimp allergy, and these showed significantly higher Der p 10 IgE levels than shrimp-tolerant ones (mean 22.2 KU/l vs 6.2 KU/l; p minor 0.05). Altogether 53% of shrimp-allergic patients did not react against tropomyosin. Conclusions. Shrimp allergy seems to occur uniquely in association with hypersensitivity to HDM allergens and tropomyosin is the main shrimp allergen but not a major one, at least in Italy. Along with tropomyosin-specific IgE levels, monosensitization to HDM seems to represent a risk factor for the development of shrimp allergy among HDM allergic patients.

Favorable Prognosis of Wheat Allergy in Adults.

BACKGROUND AND OBJECTIVE: Wheat ingestion can lead to disorders such as IgE-mediated food allergy and wheat-dependent exercise-induced anaphylaxis (WDEIA), both of which are associated with impaired quality of life and significant morbidity. Allergy to wheat is relatively benign in children, although its natural history in adults is still unknown. Objective: We used placebo-controlled challenge to evaluate the natural history of wheat hypersensitivity in atopic patients with adultonset wheat allergy. METHODS: We enrolled 13 patients from an initial cohort of adult patients with IgE-mediated wheat allergy (mean age, 40 years). After diagnosis, the patients observed a wheat-free diet and were followed as outpatients for 5 years to evaluate wheat exposure. Wheat-IgEtiters were determined at the end of follow-up, and a second wheat-challenge was performed. RESULTS: Ten out of 13 patients took part in the study. The mean period of wheat avoidance was 4.2 years. Three patients had spontaneously reintroduced wheat before the second evaluation, after a mean (IQR) of 28 (18-36) months, with only mild gastrointestinal discomfort at reintroduction. At the end of follow-up, 9 of the 10 patients were wheat-tolerant. Two patients had a history of WDEIA. We observed a reduction in IgE levels, with median (IQR) IgE falling from 2.77 (0.35-100) kU/L at diagnosis to 0.88 (0.1-20.8) kU/L. The association between IgE and a negative challenge result was not statistically significant. CONCLUSION: IgE-mediated wheat allergy in adults is benign and represents a temporary break in gastrointestinal tolerance. Future studies may improve our knowledge of wheat allergens, routes of and factors leading to sensitization, and prognostic biomarkers.

Characterization of maize chitinase-A, a tough allergenic molecule.

Food allergies are recognized as an increasing health concern. Proteins commonly identified as food allergens tend to have one of about 30 different biochemical activities. This leads to the assumption that food allergens must have specific structural features which causes their allergenicity. But these structural features are not completely understood. Uncovering the structural basis of allergenicity would allow improved diagnosis and therapy of allergies and would provide insights for safer food production. The availability of recombinant food allergens can accelerate their structural analysis and benefit specific studies in allergology. Plant chitinases are an example of food allergenic proteins for which structural analysis of allergenicity has only partially been reported. The recombinant maize chitinase, rChiA, was purified from Pichia pastoris extracellular medium by differential precipitation and cation exchange chromatography. Enzyme activity was evaluated by halo-assays and microcalorimetric procedures. rChiA modeling was performed by a two-step procedure, using the Swiss-Model server and Modeller software. Allergenicity of rChiA was verified by immunoblot assays with sera from allergic subjects. rChiA is active in the hydrolysis of glycol chitin and tetra-N-acetylchitotetraose and maintains its activity at high temperatures (70°C) and low pH (pH 3). The molecule is also reactive with IgE from sera of maize-allergic subjects. rChiA is a valuable molecule for further studies on structure-allergenicity relationships and as a tool for diagnosing allergies.

Shrimp Allergy: Analysis of Commercially Available Extracts for In Vivo Diagnosis.

BACKGROUND AND OBJECTIVE: Skin prick testing (SPT) with commercial extracts is the first step in the diagnosis of shrimp allergy, although its clinical efficiency is unknown. Objective: To analyze the clinical usefulness of all commercial crustacean extracts available for SPT in Italy. METHODS: We performed a multicenter study of 157 shrimp-allergic patients who underwent SPT with 5 commercial crustacean extracts and with house dust mite (HDM) extract. Commercial extracts were analyzed using SDS-PAGE and compared with a freshly prepared in-house shrimp extract. IgE to Pen a 1/Pen m 1, Pen m 2, and Pen m 4 was determined, and immunoblot analysis was performed on a large number of sera. RESULTS: The skin reactions caused by commercial crustacean extracts were extremely heterogeneous, resulting in 32 clinical profiles, with marked differences in protein content and missing proteins at molecular weights corresponding to those of major shrimp allergens. Only strong Pen a 1/Pen m 1 reactors reacted to both HDM and all 5 commercial extracts in SPT. Most patients, including those who were tropomyosin-negative, reacted to HDM. Patients reacted to a large and variable array of proteins, and IgE reactivity was common at high molecular weights (>50 kDa). CONCLUSIONS: The in vivo diagnosis of shrimp allergy must continue to be based on SPT with fresh material. Shrimp-allergic patients frequently react to a number of ill-defined high-molecular-weight allergens, thus leaving currently available materials for component-resolved diagnosis largely insufficient. Mites and crustaceans probably share several allergens other than tropomyosin.

Hypersensitivity to Tomato (Lycopersicon esculentum) in Peach-Allergic Patients: rPrup 3 and rPrup 1 Are Predictive of Symptom Severity.

UNLABELLED: Background: The role of allergens in the severity of tomato allergy symptoms has not yet been studied. OBJECTIVES: To evaluate the relationship between severe allergic reactions to peach and tomato and between tomato allergy symptoms and the pattern of IgE positivity for rPru p 1, rPru p 3, rPru p 4, rBetv 1, rBetv 2, rBetv4, rPhl p 1, and rPhl p 12 in order to identify the role of recombinant allergens in the severity of reactions to tomato. METHODS: We studied peach-allergic patients with clinical reactions to tomato by performing an open food challenge, skin prick test, and determination of serum specific IgE to tomato and to recombinant peach, birch, and grass allergens. Statistical analysis was carried out to evaluate the relationship between the severity of tomato symptoms and IgE positivity to the different allergens and to peach-induced symptoms. RESULTS: We found a significant association between severe reactions to tomato and severe reactions to peach (P = .01 7) and levels of IgE to rPru p3 (P = .029) and between mild tomato allergy symptoms and levels of IgE to rPru p1 (P = .047), anti-rBetv 1 (P = .0414), anti-rBetv 2 (P = .0457), and Phleum pratense (P = .0022). CONCLUSION: We observed a significant relationship between peach and symptoms of tomato allergy. IgE positivity for rPru p3 seems to be a surrogate biochemical marker for severe tomato allergy, whereas the presence of anti-rPru p 1 IgE may be an indicator of mild tomato allergy.

Two cases of elevated tryptase in abdominal aortic aneurysm.

INTRODUCTION: From the literature, patients with a history of anaphylaxis to hymenoptera venom and positive specific IgE have shown a correlation between elevated tryptase levels and two clinical situations: systemic mastocytosis and an increased risk of reactions to venom immunotherapy or hymenoptera sting. Other clinical scenarios could explain elevated tryptase levels. MATERIAL AND METHODS: A 67 year old male (P1) and a 77 year old male (P2) were evaluated for previous severe anaphylaxis to hymenoptera sting. They underwent standard diagnostic work-up for hymenoptera venom allergy. Having found elevated tryptase levels, these were followed by a bone marrow biopsy to rule out systemic mastocytosis. RESULTS: P1: specific IgE and skin tests were positive for Vespula species; tryptase 52.8 ng/ml; P2: specific IgE and skin tests were positive for Vespa cabro and tryptase 153 ng/ml. Bone marrow biopsy results were negative for mastocytosis. We carried out magnetic resonance imaging, in P1 to better characterize the severe osteoporosis and in P2 because during physical examination a pulsating mass had been identified in the mesogastrium, and an aneurysm of the abdominal aorta which required surgical intervention in both patients was detected. Eight months after surgery, tryptase levels had diminished significantly (P1: 11.6 ng/ml and P2: 14.5 ng/ml). DISCUSSION: The elevated tryptase levels were correlated to abdominal aneurysm in both patients. In fact, post-surgery tryptase levels dramatically decreased. These two cases demonstrate that high tryptase levels in subjects with a history of hymenoptera venom anaphylaxis can be associated to undiagnosed aneurysmatic disease.

Baseline serum tryptase levels and adverse reactions to injection specific immunotherapy with airborne allergens: is there a relationship?

BACKGROUND: Elevated baseline serum tryptase levels are associated with severe systemic reactions following hymenoptera stings or venom immunotherapy. Little is known about baseline tryptase levels in patients with respiratory allergy and whether a relationship exists with systemic reactions induced by injection specific immunotherapy (SIT) with airborne allergens. The objective of this study was to measure tryptase levels in subjects with respiratory allergy and analyze the results in the light of tolerance/intolerance to injection SIT. METHODS: Baseline serum tryptase levels were measured in 106 adults allergic to different airborne allergens and in 40 normal controls. Thirty-one patients underwent injection SIT, and 15 of these 31 experienced at least one SIT-induced systemic reaction. RESULTS: Patients and normal controls showed similar median tryptase levels (2.98 vs. 3.13 ng/ml, respectively), although these were elevated in 6 patients (6%) versus 0 of 40 controls (0%). Tryptase levels did not differ between those patients with or without a history of systemic reactions (median 3.7 vs. 5.91 ng/ml, not significant). Three of 4 patients showing elevated tryptase levels belonged to the SIT-tolerant group. Elevated tryptase levels were not associated with specific allergens nor with distance from the specific pollen season. A bone marrow aspirate performed in the only patient with a history of systemic reactions following injection SIT and tryptase >11.4 ng/ml showed a normal morphology and phenotype. CONCLUSIONS: Unlike patients with hymenoptera venom allergy, in patients with respiratory allergy, elevated serum tryptase levels do not represent a risk factor for adverse reactions to SIT.

Influence of cultivar and processing on cherry (Prunus avium) allergenicity.

Oral allergy syndrome is an immediate food allergic event that affects lips, mouth, and pharynx, is often triggered by fruits and vegetables, and may be associated with pollinosis. Here, we report on the allergenic pattern of different varieties of cherry (Prunus avium) and results obtained by applying several technological processes to the selected varieties. Whole cherries were submitted to chemical peeling, thermal treatment, and syruping processes, and the relative protein extracts were analyzed by in vitro (sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting analysis) and in vivo tests (skin prick test). Electrophoretic analyses demonstrated that there was no marked difference among cherry cultivars. Chemical peeling successfully removed Pru av 3, a lipid transfer protein (LTP) responsible for oral allergy syndrome in patients without pollinosis, leading to the industrial production of cherry hypoallergenic derivatives. Furthermore, the syruping process removed almost all allergenic proteins to whom patients with pollinosis are responsive. In vivo tests confirmed electrophoretic results.

[Indoor allergens in office. Evaluation of the work station]. / Il rischio da allergeni indoor negli uffici. Valutazione delle postazioni di lavoro.

House dust mite and other indoor allergens play a prominent role in the pathogenesis of asthma and other allergic diseases. Several studies have shown a close relationship between sensitisation and/or onset of asthmatic symptoms and levels of indoor allergen exposure. Aim of the study was to investigate the concentration of specific markers of the indoor allergenic pollution, such as Der p 1, Der f 1, Mite Group 2, Fel d 1 and Bla g 2. Dust samples were taken using a standard method by means of a 1200 W vacuum cleaner connected with a dust-sampling device (MITEST). A standard A4 size area has been vacuumed four times during 2 min. The concentrations of Der p 1, Der f 1, Mite Group 2, Fel d 1 and Bla g 2 were determined in dust samples from 53 different sources (office chair and carpet) using a commercial kit (DUSTSCREEN). House dust mite allergens were not always detectable in the offices. Indoor allergen concentrations (Der p 1, Der f 1, Mite Group 2, Fel d 1) were significant higher in the work station (chair) than in the carpet (p < 0.0001). Der 1 exceeded the current threshold for sensitization in about 1/4 of the samples. Der f 1 was predominant over Der p 1 according to other studies. A good correlation between the results of Der p 1 and Der f 1 was observed both in carpet and work station. Cat allergen was ubiquitous and predominantly detected in the chairs because of the employees' clothes. No appreciable levels for Mite Gr 2 and Bla g 2 were detected. Such an exposure for 8 hours in every working day may be an important occupational risk for the development of sensitization/elicitation symptoms to house dust mite. To reduce mite allergen levels are necessary preventive measure by means of specific techniques and products as barriers for preventing the direct contact with allergens.

[Sampling of airborne allergens: practical experience]. / Il campionamento degli allergeni aerodispersi: esperienze pratiche.

The availability of specific monoclonal and policlonal antibodies and the standardization of allergen extracts enables to quantify the exposure to airborne allergens in the domestic environment and at the workplace. In this article we report our experience coming from three studies based upon the measurement of airborne allergens in different environments. In a pharmaceutical factory we measured levels of laboratory animals allergens and evaluated the prevalence of sensitization to the same allergens among the workers. Airborne latex allergens and latex allergens content in latex gloves were measured in hospitals. In bakeries we evaluated the prevalence of sensitization to flour and measured flour allergens levels. The results of our studies give information useful to improve methods of prevention, diagnosis, and therapy of occupational allergic diseases.

Determination of the primary structure of two lipid transfer proteins from apricot (Prunus armeniaca).

It has been recently demonstrated that the major allergen of apricot is a protein of molecular mass (Mr) 9000 belonging to the family of Lipid Transfer Protein. The aim of this study was the determination of the primary structure of apricot LTP by micro-sequencing and mass spectrometric analyses. Apricot LTP is a 91 amino acids protein like peach and almond LTPs with a sequence identity of 91% and 94%, respectively. Like for the peach LTP, out of the 25 amino acids forming the inner surface of the tunnel-like hydrophobic cavity in maize ns-LTP, 16 are identical and 7 similar in the apricot LTP, supporting the hypothesis of a similar function.

The major allergen of sesame seeds (Sesamum indicum) is a 2S albumin.

BACKGROUND: Allergic reactions induced by ingestion of foods containing sesame seeds are a well recognized cause of severe food-induced anaphylaxis. OBJECTIVE: This study aimed to identify and characterize the clinically most important major allergen of sesame seeds. METHODS: Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and IgE immunoblotting were performed on sera of 10 patients selected for severe and documented allergic reaction after eating food containing sesame. The major allergen was purified by gel filtration and characterized by isoelectric point (pI), glycosylation and amino acid sequencing. RESULTS: All the patients had positive IgE antibodies and skin prick tests (SPTs) to sesame. The major, clinically most important allergen was a protein with molecular mass of about 9000. It was not glycosylated, the amino acid sequence showed it was a 2S albumin with a pI of 7.3; the small and the large subunits, forming the whole protein, showed pI values of 6.5 and 6.0.

Characterization of the major allergen of plum as a lipid transfer protein.

BACKGROUND: Allergy to Prunoideae fruit (plum, peach, cherry and apricot) is one of the most frequent food allergies in southern Europe. All these fruits cross-react in vivo and in vitro, as they share their major allergen, a 9 kD lipid transfer protein (LTP). OBJECTIVE: The aim of the study was the identification and molecular characterization of the major allergen of plum. METHODS: The IgE pattern of reactivity to plums was investigated by SDS-PAGE and immunoblotting with the sera of 23 patients. The identified major allergen was purified by HPLC, using a cationic-exchange column followed by gel-filtration. Further characterization was achieved by periodic-Schiff stain, isoelectrofocusing and N-terminal amino acid sequencing. RESULTS AND CONCLUSIONS: The major allergen of plum is a 9 kD lipid transfer protein, not glycosylated and with a basic character (pI>9), highly homologous to the major allergen of peach.

Lipid transfer proteins and 2S albumins as allergens.

Plant lipid transfer proteins, a widespread family of proteins, have been recently identified as important food allergens. Their common structural features, such as eight conserved cysteines forming disulfide bridges, basic isoelectric point and high similarity in amino acid sequence, are the basis of allergic clinical cross-reactivity. This has been demonstrated for the LTP allergens of the Prunoideae subfamily, whose similarity is about 95% as demonstrated for the purified allergens of peach, apricot, plum and apple. A relevant aspect is the existence of sequence homology of LTPs of botanically unrelated foods, as demonstrated for LTPs of maize and peach. A class of food allergens of well recognized clinical importance is that of seed storage 2S albumins. They have been identified in the most diffused edible seeds and nuts, such as mustard, sesame, Brazil nut, walnut and peanut. In particular, a strong correlation between IgE-binding to these proteins and food-induced anaphylaxis has been demonstrated for Brazil nut and sesame seeds.

The maize major allergen, which is responsible for food-induced allergic reactions, is a lipid transfer protein.

BACKGROUND: Cereals are the most important nutritional component in the human diet. Food-induced allergic reactions to these substances therefore have serious implications, and exhaustive diagnosis is required. Such diagnosis is still difficult because of the incomplete knowledge about major cereal allergens. In particular, few food-induced allergic reactions to maize have been reported, and no information on the allergenic proteins is available. OBJECTIVE: Having observed several anaphylactic reactions to maize, we planned a study to identify maize major allergens and cross-reactivity with other cereals, as well as to peach because the majority of patients also reacted to Prunoideae fruits. METHODS: Twenty-two patients with systemic symptoms after maize ingestion and positive skin prick test responses and serum-specific IgE antibodies to maize were selected. The IgE-reactivity pattern was identified by SDS-PAGE and immunoblotting. The major allergen identified was then purified by HPLC and characterized by mass spectrometry, determination of the isoelectric point value, and N-terminal amino acid sequencing. RESULTS: Sera from 19 (86%) of the 22 patients recognized a 9-kd protein, thus confirming this as the maize major allergen. This protein had an isoelectric point of greater than 9, a molecular mass of 9047.0 d, and no glycosylation. Determination of its N-terminal sequence showed that it was a lipid transfer protein (LTP). By using immunoblotting-inhibition experiments, we demonstrated that the LTP cross-reacts completely with rice and peach LTPs but not with wheat or barley LTPs. N-terminal sequence of the 16-kd allergen (recognized by 36% of patients) showed it to be the maize inhibitor of trypsin. This protein cross-reacts completely with grass, wheat, barley, and rice trypsin inhibitors. CONCLUSION: The major allergen of maize is an LTP with a molecular weight of 9 kd that is highly homologous with the peach LTP, the major allergen of the Prunoideae subfamily.

Evidence for a lipid transfer protein as the major allergen of apricot.

BACKGROUND: Apricots are widely grown in Europe, and allergic reactions are becoming more common, especially oral allergy syndrome. Apricot belongs to the botanical subfamily of Prunoideae, which includes peach, the major allergen of which was identified as a 9-kd protein, a lipid transfer protein (LTP). OBJECTIVE: The aim of the study was to evaluate the IgE reactivity pattern to an apricot extract in subjects with allergic reactions to apricot, as demonstrated by a positive oral challenge response. METHODS: Thirty patients were investigated. All the patients displayed oral allergy syndrome (2 with systemic reactions) to apricot, with positive open food challenge responses, skin prick test responses, and serum-specific IgE antibodies to apricot. The IgE reactivity pattern to apricot extract was identified by using SDS-PAGE and immunoblotting. The major allergen, a 9-kd protein, was then purified by HPLC and characterized by periodic acid-Schiff stain, isoelectric point determination, and N-terminal amino acid sequencing. RESULTS: The sera from all patients allergic to apricot recognized the 9-kd protein, whereas none of the other allergens, with molecular weights from 15 to 80 kd, acted as a major allergen. The 9-kd allergen has an isoelectric point of 8.7 and is not glycosylated. Determination of the N-terminal 34 amino acid sequence showed that it belongs to the LTP family, with a 94% homology with the LTP from peach. IgE blotting of the apricot extract was completely inhibited by the 9-kd purified LTP from peach. CONCLUSIONS: The major allergen of apricot is an LTP, which is highly cross-reactive with the LTP from peach.