Profilin as a severe food allergen in allergic patients overexposed to grass pollen.

BACKGROUND: Profilins are ubiquitous proteins that act as panallergens in sensitized patients, considered to be mild or incomplete food allergens. The aim of the study was to evaluate the role of profilins as severe food allergens in allergic patients overexposed to grass who were referred for severe food reactions and were sensitized to profilins. METHODS: After a careful in vitro screening, 26 patients were included, classified into two groups, mild (17) and severe reactors (9), based on clinical history and subsequently provoked orally with purified profilin in a double-blind placebo-controlled food challenge setup. RESULTS: A significant number of patients presented severe positive food challenge test reactions at low doses of the allergen profilin. Patients prone to suffer from severe reactions had lower IgG4/IgE ratio to major grass allergens than those who did not. CONCLUSION: Profilins are complete food allergens in food-allergic patient populations that are exposed to high levels of grass pollen. This type of patient constitutes an optimal model to understand the link between respiratory and food allergies. The nature of the observed reactions and the low level of allergen eliciting the reactions suggest that intake through the oral mucosa might constitute a relevant route of exposure to food allergens.

Molecular characterization of contact urticaria in patients with melon allergy.

BACKGROUND: The relevance of contact allergy to plant-related food has recently emerged. Oral allergy syndrome is one of the most characteristic symptoms of fruit allergy, although it also causes systemic reactions. Plant-food allergy is increasing at the same time as pollen allergy, and fruit-induced allergic contact urticaria could be rising as well. OBJECTIVES: The present study was carried out in order to investigate whether one particular primary melon-peel allergen is responsible for contact urticaria. METHODS: Fourteen patients presenting with contact urticaria after touching melon peel were evaluated. A melon-peel extract was prepared and analysed by immunoblotting using the patients' sera. Molecular characterization of IgE-binding bands was performed using mass spectrometry. Melon-peel lipid transfer protein (LTP) was purified. Inhibition studies and contact challenge with the protein were performed to confirm IgE reactivity to the purified allergen. RESULTS: An IgE-binding band of ~8-9 kDa was observed in an immunoblotting assay with all the patients' sera and was identified as an LTP. The melon-peel LTP was purified in two chromatography steps. Inhibition studies confirmed LTP as a major allergen in patients with melon-peel contact urticaria. Contact challenge with melon-peel LTP was performed in five patients, all of whom had positive results, exhibiting itchy erythema and hives in the area of contact. CONCLUSIONS: This study confirmed our previous findings that melon-peel LTP is a major allergen and is responsible for contact allergy. This knowledge may be used to improve both diagnosis and treatment of patients allergic to melon.

Assessment of effects on health due to consumption of bitter bottle gourd (Lagenaria siceraria) juice.

BACKGROUND & OBJECTIVES: The bottle gourd (Lagenaria siceraria) is popularly known as lauki, ghia or dudhi in India. Its consumption is advocated by traditional healers for controlling diabetes mellitus, hypertension, liver diseases, weight loss and other associated benefits. However, in last few years there have been reports of suspected toxicity due to consumption of its juice. This led to the constitution of an Expert Committee by Department of Health Research at Indian Council of Medical Research (ICMR), Ministry of Health & Family Welfare, Government of India in October 2010. The committee looked into the issues related to safety of consumption of bottle gourd juice, and this paper presents the findings. METHODS: Information on cases of suspected toxicity due to consumption of bottle gourd juice was collected by internet search, advertising on website of ICMR and by writing to State and district health authorities as well as to medical colleges, hospitals and private nursing homes across the country. RESULTS: Three deaths were reported, one from Delhi and two from Uttar Pradesh after consumption of extremely bitter bottle gourd juice. Three persons who died after consumption of freshly prepared bottle gourd juice or juice mixed with bitter gourd (karela) juice were over 59 years of age and had diabetes since last 20 years. This juice was reported to be extremely bitter by all three. Twenty six persons were admitted to various hospitals of the country on complaint of abdominal pain and vomiting following consumption of freshly prepared bottle gourd juice. Diarrhoea and vomiting of blood (haematemesis) was reported in 18 (69.2%) and 19 (73.1%) patients, respectively. Biochemical investigations revealed elevated levels of liver enzymes. More than 50 per cent patients had hypotension. Endoscopic findings showed profusely bleeding stomach with excessive ulceration seen in distal oesophagus, stomach and duodenum in most of the cases. All these patients recovered fully and no sequeale was recorded for any of the cases. INTERPRETATION & CONCLUSIONS: Cucurbitaceae family, of which bottle gourd is a member contains the toxic tetracyclic triterpenoid compounds called cucurbitacins which are responsible for the bitter taste. There is no known antidote for this toxicity and clinicians treat such cases symptomatically only. The Committee made the following recommendations: (i) The community needs to be educated that bitter tasting bottle gourd juice should not be consumed and in case there is any discomfort, nausea, vomiting, diarrhoea or any feeling of uneasiness after consumption of juice, the person should immediately be taken to a nearby hospital. (ii) Clinicians are suggested that patients coming with symptoms (discomfort, nausea, vomiting, diarrhoea, gastrointestinal bleeding after consumption of juice) should immediately be attended to and general supportive care should be provided, i.e. IV fluids/crystalloids/blood products/fresh frozen plasma to maintain the haemodynamics and electrolyte balance; Ryle's tube to be put in for gastric lavage and to assess gastrointestinal (GI) bleed- aspirate to be preserved; Proton pump inhibitors should be given for management of GI bleed and appropriate treatment for other complications should be given. (iii) The possible research areas identified are chemical composition studies on bitter and normal bottle gourd and other members of cucurbitaceae family; animal toxicity studies and studies on interaction between bottle gourd juice and other drugs.

Diagnostic evaluation of grass- and birch-allergic patients with oral allergy syndrome.

BACKGROUND: Patients with birch and grass allergy often suffer from oral allergy symptoms when ingesting cross-reacting fresh fruits and vegetables. However, fruit and vegetable allergen extracts are often readily degradable or contain clinically irrelevant cross-reacting epitopes, resulting in diagnostic discrepancies when fruit and vegetable allergic reactions are evaluated. The risk of using nonstandardized fresh food extracts for skin testing may also be of concern. The objective was to compare and evaluate the clinical utility of selected recombinant grass and birch cross-reacting food allergens with fresh and commercial melon, hazelnut, and apple extracts. METHODS: Thirty-six grass- and or birch-allergic patients and 17 control subjects consented to participate in the study. All subjects were skin prick tested and had basophil histamine-release tests done with fresh fruits and various extracts of hazelnut, apple, and melon. The diagnosis of oral allergy syndrome was confirmed by oral challenges. In addition, histamine release to recombinant Bet v 1 and Bet v 2, and recombinant Phl p 1 and Phl p 2, Phl p 5 was performed. RESULTS: The skin prick test with fresh hazelnut, apple, and melon showed sensitivities of 0.97, 0.92, and 0.89, respectively. The corresponding specificities were 0.78, 0.72, and 0.82, respectively. In contrast, the histamine-release test with hazelnut, apple, and melon gave sensitivities of 0.87, 0.71, and 1.00, respectively. The corresponding specificities were 0.65, 0.93, and 0.43. The skin prick test showed excellent negative predictive value (> 90%). No added value of recombinant allergen testing was noted. Oral challenge did not result in severe systemic reactions, and no systemic reactions were observed with skin prick tests with fresh fruits. CONCLUSION: The skin prick test showed an almost optimal diagnostic value with a satisfactory sensitivity (> 89%) and excellent negative predictive value with fresh fruits. When the skin prick test with fresh nut and apple cannot be performed, histamine release is a diagnostic alternative. Histamine release with melon showed lack of specificity. This was probably due to extensive IgE cross-reactivity with pollen, since these patients also responded to recombinant Phl p 1 and Bet v 1. Skin testing and challenges with fresh fruits were safe.

Allergy caused by ingestion of zucchini (Cucurbita pepo): characterization of allergens and cross-reactivity to pollen and other foods.

BACKGROUND: Allergy to zucchini (Cucurbita pepo), a member of the Cucurbitaceae family, has not previously been reported. We examined 4 patients complaining of allergic symptoms, such as oral allergy syndrome, nausea, diarrhea, or pruritus, after the intake of zucchini. OBJECTIVE: After the confirmation of food allergy, we wanted to characterize zucchini allergens and examine possible cross-reactions to pollen and food. METHODS: The patients underwent skin prick and prick-to-prick-testing with different allergens, including zucchini, latex, and birch, ragweed, and grass pollen. Moreover a double-blind, placebo-controlled, food challenge was performed to confirm food allergy. Total and specific serum IgE levels were determined by using CAP-FEIA and the enzyme allergosorbent test method (EAST), respectively. Proteins from zucchini reacting with patient IgE were detected by means of immunoblotting. To characterize cross-reacting IgE antibodies, immunoblot- and EAST-inhibition assays were carried out. RESULTS: All patients in this study had positive reactions to zucchini both in prick-to-prick tests and double-blind, placebo-controlled, food challenges. Specific serum IgE levels to zucchini were found in all cases. In blot- and EAST-inhibition assays IgE from two patients revealed binding to zucchini profilin at about 15 kd. Furthermore, in two cases, including one of the profilin-positive patients, IgE directed against cross-reacting carbohydrate determinants was detected. For one patient, no cross-reacting IgE could be found, but IgE from this patient reacted strongly with a zucchini protein at 17 kd. CONCLUSIONS: We report the first 4 cases of food allergy to zucchini. Zucchini allergens can cause systemic reactions and are at least partially heat stable. We suggest that allergy to zucchini can occur as a result of primary sensitization to zucchini, as well as to cross-reactions to the panallergen profilin and cross-reacting carbohydrate determinants.

Fennel, cucumber, and melon allergy successfully treated with pollen-specific injection immunotherapy.

BACKGROUND: In subjects with both pollinosis and vegetable food allergy, most allergenic epitopes of fruits and vegetables are present in pollen. A recent study showed a marked reduction or a total disappearance of apple-induced oral allergy syndrome in patients receiving injection immunotherapy with birch pollen extracts. OBJECTIVE: To assess whether vegetable food allergy following other kinds of primary pollinosis may be successfully treated with pollen-specific immunotherapy. METHODS: A 34-year-old woman with long-standing pollinosis and typical oral allergy syndrome (OAS) with the ingestion of both fennel and cucumber and whose OAS was associated with immediate laryngeal edema after the ingestion of melon, was treated with two commercial depot aluminum hydroxide-adsorbed extracts of 1 grass pollen and 2 mugwort pollen 50% + ragweed pollen 50%. RESULTS: After 36 months of injection specific immunotherapy, the patient was able to tolerate both fresh fennel and cucumber without consequence on open oral challenge tests. After 43 months of immunotherapy, the patient tolerated fresh melon as well on open oral challenge. She has re-introduced these vegetables in her normal diet. Skin tests showed no reactivity to fresh fennel and there was a reduction of the wheal induced by fresh cucumber. CONCLUSION: Vegetable food allergy following primary sensitization to pollens, other than birch, may also be effectively reduced by pollen-specific injection immunotherapy.