Search

Seed storage proteins are extremely stable allergens in nuts, seeds, and legumes and are responsible for the most severe allergic reactions to these foods. The cross-reactivity between seed storage proteins from different sources has not been studied at a molecular level so far. This study aimed to ascertain the cross-reactivity between walnut and hazelnut seed storage proteins using recombinant allergens. Sera from 13 consecutive patients with severe primary walnut and/or hazelnut allergy and hypersensitive to both nuts were studied. IgE specific for rCor a 9, rCor a 14, and rJug r 1 was measured, and inhibition experiments were carried out by measuring IgE reactivity after absorption of patients’ sera with freshly prepared walnut extract. All 13 sera showed strong IgE reactivity against walnut 2S albumin, Jug r 1, 12 reacted to hazelnut 2S albumin, Cor a 14, and 8 to the hazelnut legumin, Cor a 9. In inhibition experiments, absorption of sera with whole walnut extract led to the complete disappearance of IgE reactivity to Jug r 1 in 12/13 cases, as expected, but also to the complete disappearance of specific IgE to Cor a 14 in 9/12 sera, and of IgE reactivity to Cor a 9 in 7/8. In the remaining cases a dramatic drop in IgE reactivity was observed. The study shows that patients primarily allergic to either walnut or hazelnut showing a skin or serological reactivity to the other nut also are potentially at risk of severe allergic reactions caused by cross-reactivity between 2S albumins and legumins.

Mosquito bite is usually followed by a local reaction, but severe or systemic reaction may, in rare cases, occur. Allergic reactions to Aedes communis (Ac) may be underestimated due to the lack of reliable diagnostic tools. In this multicenter study, 205 individuals reporting large local reactions to Ac were enrolled and studied for cutaneous or IgE reactivity to Ac, Blattella germanica, Penaeus monodon, and Dermatophagoides pteronyssinus. Extract and molecular IgE reactivity to bees, wasps, hornets, and yellow jacket venoms were also studied in 119 patients with a clinical history of adverse reaction to Hymenoptera. Immunoblot (IB) analysis and immunoCAP IgE inhibition experiments were carried out in selected sera. Ac sensitization was recorded in 96 (46.8%) patients on SPT. Strict relationship between Ac and D. pteronyssinus, B. germanica, P. monodon, or Apis mellifera reactivity on SPT was observed. Ac IgE recognition was seen in 60/131 (45.8%) patients, 49 (81.6%) of them SPT positive, and 5/14 IB reactors. Ac IgE sensitization was associated with Tabanus spp, A. mellifera, Vespula vulgaris, and Polistes dominula reactivity. A strict relationship between Ac IgE reactivity and Api m 1, Api m 2, Api m 3, Api m 5, and Api m 10 was recorded. IgE reactivity to AC was inhibited in 9/15 cases after serum absorption with the A. mellifera extract. Both SPT and IgE Ac reactivity is observed in about half of patients with a history of large local reactions to mosquito bites. The significant relationship between Ac sensitization and either extract or single bee venom components is suggestive of a “bee-mosquito syndrome” occurrence.

Background: Shrimp is a frequent cause of food allergy worldwide. Besides tropomyosin, several allergens have been described recently. Objective: We investigated which allergens are involved in Italian shrimp-allergic adults. Methods: Sera from 116 shrimp-allergic patients selected in 14 Italian allergy centers were studied. Skin prick tests with house dust mite (HDM) as well as measurements of IgE to Pen a 1 (shrimp tropomyosin) and whole shrimp extract were performed. All sera underwent shrimp immunoblot analysis, and inhibition experiments using HDM extract as inhibitor were carried out on some Pen a 1-negative sera. Results: Immunoblots showed much variability. IgE reactivity at about 30 kDa (tropomyosin) was found in 90 kDa was frequent. Further reactivities at 14–18, 25, 43–50, about 60 and about 80 kDa were detected. Most subjects had a history of shrimp-induced systemic symptoms irrespective of the relevant allergen protein. IgE to Pen a 1 were detected in sera from 46 (41%) patients. Skin reactivity to HDM was found in 43/61 (70%) Pen 1-negative subjects and inhibition studies showed that pre-adsorption of sera with HDM extract induced a marked weakening of the signal at >67 kDa. Conclusions: Several allergens other than tropomyosin are involved in shrimp allergy in adult Italian patients. Some hitherto not described high molecular weight allergens seem particularly relevant in this population and their cross-reactivity with HDM allergens makes them novel potential panallergens of invertebrates.

Background: Due to unclear reasons, allergy to lipid transfer protein (LTP) is frequent in Mediterranean countries but rare in Northern Europe. Objective: We report a paradigmatic case of primarily airborne sensitization to LTP that might explain the geographical distribution of this type of food allergy. Methods: A 21-year-old woman began having severe perennial rhinitis 6 months after she started working in a wholesale fruit storehouse in Southern Italy where large amounts of fruits, including peaches, were handled; symptoms subsided when she left the workplace for >5 days and relapsed as soon as she was back at work. Later on, she developed severe food allergies to peach, hazelnut, peanut, apricot, plum and tomato. The patient underwent a nasal challenge with peach peel extract, and IgE reactivity was assessed by immunoblot analysis. Results: In vivo and in vitro analyses showed sensitivity to LTP. The nasal challenge with peach peel extract (6 µg protein) induced acute, severe respiratory symptoms. On immunoblot with peach peel extract patient’s serum reacted uniquely against LTP, as demonstrated by inhibition assays with the recombinant peach protein. Conclusion: LTP may induce sensitization via the respiratory tract due to inhalation of air-dispersed food particles, and this may precede the onset of food allergy. If this way of sensitization were effective in the majority of LTP allergic patients (e.g. by exposure to peaches showing intact fuzz in areas where peaches are grown and directly sold on the market) our findings could explain the strange geographical distribution of this type of food allergy.

Background: Lipid transfer protein (LTP) is a widely cross-reacting plant pan-allergen. Adverse reactions to Rosaceae, tree nuts, peanut, beer, maize, mustard, asparagus, grapes, mulberry, cabbage, dates, orange, fig, kiwi, lupine, fennel, celery, tomato, eggplant, lettuce, chestnut and pineapple have been recorded. Objective: To detect vegetable foods to be regarded as safe for LTP-allergic patients. Methods: Tolerance/intolerance to a large spectrum of vegetable foods other than Rosaceae, tree nuts and peanut was assessed by interview in 49 subjects monosensitized to LTP and in three distinct groups of controls monosensitized to Bet v 1 (n = 24) or Bet v 2 (n = 18), or sensitized to both LTP and birch pollen (n = 16), all with a history of vegetable food allergy. Patients and controls underwent skin prick test (SPT) with a large spectrum of vegetable foods. The absence of IgE reactivity to foods that were negative in both clinical history and SPT was confirmed by immunoblot analysis and their clinical tolerance was finally assessed by open oral challenge (50 g per food). Results: All patients reported tolerance and showed negative SPT to carrot, potato, banana and melon; these foods scored positive in SPT and elicited clinical symptoms in a significant proportion of patients from all three control groups. All patients tolerated these four foods on oral challenge. Immunoblot analysis confirmed the lack of IgE reactivity to these foods by LTP-allergic patients. Conclusion: Carrot, potato, banana and melon seem safe for LTP-allergic patients. This finding may be helpful for a better management of allergy to LTP.

Background: In patients showing multiple reactivity to seasonal airborne allergens, a skin prick test (SPT) with Parietaria pollen scores frequently negative, suggesting that profilin from Parietaria might not share IgE-binding epitopes with profilin from botanically unrelated airborne allergens. This study investigated the immunologic cross-reactivity between profilins from Parietaria, grass and birch pollen. Methods: 36 patients hypersensitive to birch profilin, Bet v 2, underwent SPT with Parietaria, and IgE to both whole Parietaria pollen and Phleum profilin were sought in their sera by ELISA. In ELISA inhibition studies, IgE reactivity to Phleum profilin was measured before and after absorption of sera from Parietaria reactors with both whole Parietaria pollen extract, and Par j 1/Par j 2 fraction. Further, their IgE reactivity to whole Parietaria pollen was measured before and after absorption with the Par j 1/Par j 2 fraction. Results: All sera showed IgE reactivity to Phleum profilin. Only 14/36 (39%) patients had a positive SPT to Parietaria and 17/36 (47%) showed IgE to Parietaria. Absorption of sera from Parietaria reactors with whole Parietaria extract caused a marked reduction in IgE reactivity to grass profilin; in contrast, absorption of sera with the Par j 1/Par j 2 fraction did not exert any inhibitory effect on IgE reactivity to grass profilin. Absorption of sera with the Par j 1/Par j 2 fraction markedly reduced IgE reactivity to whole Parietaria extract in 8/9 cases. Conclusion: Less than 50% of patients sensitized to birch and grass profilin cross-react to Parietaria profilin. In most cases, cross-reactors are hypersensitive to major, specific Parietaria allergens as well. This findings may be of practical relevance when the prescription of specific immunotherapy is considered.

Background: Cupressaceae (cypress) pollens can cause pollinosis in winter. However, the lack of specific commercial extracts combined with the early pollination period of cypress trees make a precise diagnosis difficult. The need for a reliable and effective cypress extract for diagnostic and therapeutic purposes is increasingly felt. Methods: Mixed or single Cupressus arizonica, lusitanica and sempervirens pollen extracts precipitated with ammonium sulfate (PPT) were compared by direct RAST, RAST inhibition and SDS-PAGE techniques. The major allergen of C. arizonica (Cup a 1), purified by anion exchange chromatography, was checked by immunoblotting experiments before chemical modification, in parallel with a C. arizonica extract, with potassium cyanate (KCNO) to obtain a monomeric allergoid. The allergoid extract was characterized for its biological, chemico-physical and immunological features by RAST inhibition, SDS-PAGE and ELISA assays. Results: Direct RAST, RAST inhibition, and SDS-PAGE data indicated that the PPT C. arizonica pollen extract showed the most allergenic potential, and it can be considered representative of the Cupressus spp. Immunoblotting data confirmed Cup a 1 as a major allergen. RAST inhibition and ELISA showed that modified PPT C. arizonica extract had less IgE reactivity than the native, non-modified extract, while preserving the immunogenic capacity typical for an allergoid. Finally, the SDS-PAGE profile of Cup a 1 allergoid was similar to native Cup a 1 allergen, suggesting the modified C. arizonica extract shows the characteristics of a monomeric allergoid. Conclusions: The PPT C. arizonica pollen extract shows good in vitro diagnostic potential and its chemically modified form offers the features of a monomeric allergoid. It might therefore lend itself to the development of a product to be administered by the sublingual or oromucosal route for immunotherapy of individuals with cypress pollinosis.

This case report describes a patient with bee moth-induced rhinoconjunctivitis, asthma and contact urticaria. Immunoblot analysis showed IgE reactivity to two distinct bee moth proteins at 23 and 70 kDa, respectively. ELISA inhibition studies excluded cross-reactivity to the other popular live bait, fly larva.