"Atopy patch tests" in the diagnosis of delayed food hypersensitivity

The prevalence of atopic diseases is increasing worldwide. Food allergies are the earliest manifestation of atopy. Atopic eczema affects about 18% of infants in the first 2 years of life and the main cause is allergy to multiple foods. A strong association has been shown between atopic eczema and IgE mediated allergy to milk, egg or peanut, but more than two-thirds of patients intolerant to food proteins have no evidence of IgE sensitization to the relevant food protein. Recently, patch testing with proteins has been found to be helpful in diagnosing food allergy in cases where skin prick tests and estimation of specific antibodies have failed. The methodology of atopy patch test (APT) is unstandardized, and contradictory results have been reported. In contrast to the more standardized APT methodology with aeroallergens, the sensitivities and specificities of food allergens can easily be estimated with food challenge tests. With multiallergic children adding of APTs to the skin prick tests and specific antibody estimation tests give more information for planning a wide enough elimination diet to get the skin and gastrointestinal tract symptomless in order to perform the challenge test which remains the only reliable test for food allergy. Standardization of the APT materials and reading procedure will add to the reliability of this new test method.

[Allergenicity of wheat flour]

Food allergy to wheat flour is a pathology that is found less frequently than coeliac disease or respiratory allergy to flour; it seems however to be a constant argument. Our study used a panel of 28 patients diagnosed with food allergy to wheat flour. Our objective was to characterise the reactivity of type IgE and IgG antibodies of these patients with regard to the different classes of proteins of wheat flour so as to establish an antigenic profile of the allergens of wheat in the framework of food allergy to flour. Our results show the implication of different classes of wheat proteins and notably the major reserve proteins (gliadins and glutens) in food allergy.

IgE binding to soluble and insoluble wheat flour proteins in atopic and non-atopic patients suffering from gastrointestinal symptoms after wheat ingestion

BACKGROUND

The involvement of IgE-mediated hypersensitivity reactions in the genesis of gastrointestinal symptoms after ingestion of foods containing wheat has been rarely reported.

OBJECTIVE

To detect IgE specifically binding to wheat proteins in the sera of atopic and non-atopic patients suffering from gastrointestinal symptoms after ingestion of wheat and to evaluate the reliability of skin prick test and CAP in the diagnosis of food allergy to wheat.

METHODS

The sera of patients (10 atopic and 10 non-atopic) previously diagnosed as suffering from irritable bowel syndrome and complaining of symptoms after wheat ingestion were analysed by immunoblotting for IgE binding to water/salt-soluble and insoluble wheat flour proteins.

RESULTS

All the atopic patients and only one of the non-atopic patients were positive to wheat CAP. For the patients tested, skin prick test was positive for all the atopic patients and for only one of the non-atopic patients. However, immunoblotting experiments showed the presence of specific IgE to wheat proteins in all the patients. Ten out of 11 of the wheat CAP-positive patients had IgE binding to a soluble 16-kDa band, but the same band was recognized, in a slighter way, by only two out of nine of the wheat CAP-negative patients. Moreover, although almost all of the patients were negative in CAP testing with gluten, 19 out of 20 recognized protein bands belonging to the prolamin fraction.

CONCLUSIONS

For the atopic patients the positivity to skin prick test and CAP to wheat was in accordance with the immunoblotting results and a food allergy to wheat could be diagnosed. In these patients a major allergen was a 16-kDa band corresponding to members of the cereal alpha-amylase/trypsin inhibitors protein family, the major allergens involved in baker's asthma. In the non-atopic patients the positive immunoblotting results contrasted with the responses of the allergologic tests, indicating that the allergenic wheat protein preparations currently used are of limited value in detecting specific IgE to wheat and that the fraction of irritable bowel syndrome (IBS) patients with food allergy may be larger than believed.

Wheat omega-5 gliadin is a major allergen in children with immediate allergy to ingested wheat

BACKGROUND

Sensitization to wheat by ingestion can lead to food allergy symptoms and wheat-dependent, exercise-induced anaphylaxis. Sensitization by inhalation causes bakers' asthma and rhinitis. Wheat allergens have been characterized at the molecular level in bakers' asthma and in wheat-dependent, exercise-induced anaphylaxis, in which omega-5 gliadin (Tri a 19) is a major allergen. However, little information is available regarding allergens responsible for hypersensitivity reactions to ingested wheat in children.

OBJECTIVE

The aim of this study was to examine whether children with allergy to ingested wheat have IgE antibodies to omega-5 gliadin.

METHODS

Sera were obtained from 40 children (mean age, 2.5 years; range, 0.7-8.2 years) with suspected wheat allergy who presented with atopic dermatitis and/or gastrointestinal and/or respiratory symptoms. Wheat allergy was diagnosed with open or double-blinded, placebo-controlled oral wheat challenge. Wheat omega-5 gliadin was purified by reversed-phase chromatography, and serum IgE antibodies to omega-5 gliadin were measured by means of ELISA. In vivo reactivity was studied by skin prick testing. Control sera were obtained from 22 children with no evidence of food allergies.

RESULTS

In oral wheat challenge, 19 children (48%) reacted with immediate and 8 children (20%) with delayed hypersensitivity symptoms. Sixteen (84%) of the children with immediate symptoms had IgE antibodies to purified omega-5 gliadin in ELISA. In contrast, IgE antibodies to omega-5 gliadin were not detected in any of the children with delayed or negative challenge test results or in the control children. The diagnostic specificity and positive predictive value of omega-5 gliadin ELISA were each 100% for immediate challenge reactions. Skin prick testing with omega-5 gliadin was positive in 6 of 7 children with immediate challenge symptoms and negative in 2 children with delayed challenge symptoms.

CONCLUSION

The results of this study show that omega-5 gliadin is a significant allergen in young children with immediate allergic reactions to ingested wheat. IgE testing with omega-5 gliadin could be used to reduce the need for oral wheat challenges in children.

Exposure to wheat allergen and fungal alpha-amylase in the homes of bakers

BACKGROUND

Few data are available on exposure to occupational allergens in dwellings occupied by inhabitants with occupational exposure to allergens. In small bakeries working and living often takes place in the same building. It is possible that allergens from the bakery can be transported into the homes of the bakers, via the clothes or shoes of the baker.

OBJECTIVE

The aims of this study were to investigate exposure to occupational allergens, wheat and fungal alpha-amylase in the homes of bakers, and evaluate potential determinants of exposure. Sensitization in family members to occupational allergens was investigated in a small preliminary survey.

METHODS

Floor dust samples were collected in the homes of 34 bakers. Levels of wheat and fungal alpha-amylase allergens were determined in an extract of the dust samples. Blood samples were collected from bakers and their family members to determine the prevalence of sensitization to occupational allergens.

RESULTS

The concentration of wheat and alpha-amylase allergens ranged from 38.9 to 172.4 microgeq/m(2) (GM), to 10.5-76.7 ngeq/m(2) (GM). Higher levels of dust and allergens were measured when the house could be reached directly through the bakery, and in houses with textile floor covers. Higher concentrations were also measured when bakers brought their work clothes and shoes into the house and when textiles from the bakery were laundered at home. Some family members appeared to be sensitized to wheat flour and alpha-amylase, but it cannot be excluded that they became sensitized because of their incidental presence in the bakery.

CONCLUSIONS

Occupational allergens can be found in house dust from the homes of bakers and levels are associated with hygienic behaviour and distance to the bakery.

Aspirin enhances the induction of type I allergic symptoms when combined with food and exercise in patients with food-dependent exercise-induced anaphylaxis

We examined the effect of aspirin as a substitute for exercise in inducing urticaria/anaphylaxis in three patients with food-dependent exercise-induced anaphylaxis (FDEIA). Two of the patients had specific IgE antibodies to wheat and the other had antibodies to shrimp. Administration of aspirin before ingestion of food allergens induced urticaria in one patient and urticaria and hypotension in another, while aspirin alone or food alone elicited no response. The third patient developed urticaria only when he took all three items, i.e. aspirin, food and additional exercise, whereas provocation with any one or or two of these did not induce any symptoms. These findings suggest that aspirin upregulates type I allergic responses to food in patients with FDEIA, and further shows that aspirin synergizes with exercise to provoke symptoms of FDEIA. This is the first report of a synergistic effect of aspirin in inducing urticaria/anaphylaxis, which was confirmed using challenge tests in patients with FDEIA.

The necessity for dual food intake to provoke food-dependent exercise-induced anaphylaxis (FEIAn): a case report of FEIAn with simultaneous intake of wheat and umeboshi

BACKGROUND

Food-dependent exercised-induced anaphylaxis (FEIAn) is classified among the physical allergies. Many different food allergens have been reported, but the pathophysiology of FEIAn remains unknown. Furthermore, provocation tests with a suspected food do not always succeed in patients with FEIAn.

OBJECTIVE

We sought to clarify and investigate causative foods and mechanisms of FEIAn in a 14-year-old boy. In addition, we tested in vivo and in vitro effects of cromolyn sodium in the same patient.

METHODS

We used open challenge tests for the provocation of FEIAn and measured changes in plasma histamine levels and FEV1. In addition, we investigated the mechanism of FEIAn in this case with in vitro histamine release testing.

RESULTS

The patient was diagnosed as having FEIAn by provocation testing with a simultaneous intake of wheat and umeboshi, but not when each food was eaten singly, followed by exercise. In addition, his plasma histamine level increased transiently and forced expiratory volume 1, expressed as a percentage change from baseline, decreased significantly. A synergistic effect on in vitro histamine release testing with 2 kinds of the causative foods was shown. Administration of cromolyn sodium proved to be effective on both the in vitro and in vivo tests.

CONCLUSION

This is the first report of FEIAn provoked by the test with a simultaneous intake of 2 kinds of food. This case might in part explain negative challenge test results in patients with FEIAn.

Dietary factors in relation to the distribution of duodenal ulcer in India as assessed by studies in rats

BACKGROUND

The prevalence of duodenal ulcer is less in the northern wheat-eating regions of India and China than in the southern rice-eating areas.

METHODS AND RESULTS

Experiments were conducted on rat peptic ulcer models in which controls were fed on either known ulcerogenic rice or rice plus tapioca diets or on non-ulcerogenic stock diet. By using an ulcerogenic diet and pyloric ligation, unrefined wheat, wheat bran and their respective oils were protective against ulceration. Refined wheat, wheat germ and its oil were not protective. Freshly milled rice and unmilled rice were protective, but stored rice bran and its oil increased the ulceration. Fresh rice bran oil was not ulcerogenic, but on storage, it became ulcerogenic. By using stock diet and alcohol-induced ulceration, the findings with whole wheat oil, wheat bran and wheat germ oil were confirmed. Rats fed on the stock diet subjected to pyloric ligation developed ulcers following intragastric injection of stored rice bran oil. This ulcerogenicity was counteracted by whole wheat oil.

CONCLUSION

These results suggest that the factor of diet may well explain the regional differences in the prevalence of duodenal ulceration between North and South India and China where other etiologic factors are similar.

Identification of wheat flour allergens by means of 2-dimensional immunoblotting

BACKGROUND

Wheat flour proteins are allergens for 60% to 70% of bakers with workplace-related respiratory symptoms.

OBJECTIVE

The aim of the study was to investigate the variability of IgE antibody patterns of wheat flour-sensitized bakers and to identify the most frequently recognized allergens.

METHODS

Water/salt-soluble wheat flour proteins from the cultivar Bussard were separated by using 2-dimensional gel electrophoresis with immobilized pH gradients. IgE-reactive proteins were identified by means of immunoblotting with sera of 10 subjects with baker's asthma. Mass spectrometric fingerprinting was used to identify the proteins most frequently recognized by IgE.

RESULTS

The IgE immunoblots obtained with 10 different sera exhibited a remarkable heterogeneity. Each patient showed an individual IgE-binding pattern with 4 to 50 different allergen spots. Altogether, more than 100 IgE-binding protein spots were detected. Nine of the predominant IgE-binding protein spots were identified by using mass spectrometric fingerprinting. The obtained masses matched 2 different isoforms of glycerinaldehyde-3-phosphate dehydrogenase from Hordeum vulgare, triosephosphate isomerase from H vulgare, and serpin, a serine proteinase inhibitor from Triticum aestivum.

CONCLUSIONS

The results show a great interindividual variation of IgE-binding patterns of wheat flour proteins in baker's asthma. The clinical relevance of the identified 4 new allergens will be further investigated in the near future.

Respiratory arrest in a male athlete after running through a wheat field

A male athlete suffered complete respiratory arrest after collapsing at the entrance to an Accident and Emergency Department of a hospital. He was resuscitated and recovered fully after several hours. He had multiple wheals on both legs and had complained of severe breathlessness before collapsing. The athlete had run through a wheat field, upon finding his usual pathway overgrown, which had caused wheat pollen to be released. He had been a mild asthmatic for 30 years and had recalled some mild urticaria after exercise but had never experienced exercise-induced asthma, or hay fever. Subsequent allergy tests showed negative for wheat but positive for house dust mite and grass mix. It is possible that the symptoms were triggered either by the running itself, inhalation of allergens other than wheat pollen, skin abrasions caused by contact with wheat stalks, or a combination of these factors.

Utility of food-specific IgE concentrations in predicting symptomatic food allergy

BACKGROUND

The double-blind, placebo-controlled food challenge is considered the gold standard for diagnosing food allergy. However, in a retrospective analysis of children and adolescents with atopic dermatitis and food allergy, discrete food-specific IgE concentrations were established that could predict clinical reactivity to egg, milk, peanut, and fish with greater than 95% certainty.

OBJECTIVE

The purpose of this investigation was to determine the utility of these 95% predictive decision points in a prospective evaluation of food allergy.

METHODS

Sera from 100 consecutive children and adolescents referred for evaluation of food allergy were analyzed for specific IgE antibodies to egg, milk, peanut, soy, wheat, and fish by using the Pharmacia CAP System FEIA. Food-specific IgE values were compared with history and the results of skin prick tests and food challenges to determine the efficacy of previously established 95% predictive decision points in identifying patients with increased probability of reacting during a specific food challenge.

RESULTS

One hundred children (62% male; median age, 3.8 years; range, 0.4-14.3 years) were evaluated for food allergy. The diagnosis of food allergy was established by means of history or oral food challenge. On the basis of the previously established 95% predictive decision points for egg, milk, peanut, and fish allergy, greater than 95% of food allergies diagnosed in this prospective study were correctly identified by quantifying serum food-specific IgE concentrations.

CONCLUSION

In a prospective study of children and adolescents referred for evaluation of food allergy, previously established 95% predictive decision points of food-specific IgE antibody concentrations for 4 major food allergens were effective in predicting clinical reactivity. Quantification of food-specific IgE is a useful test for diagnosing symptomatic allergy to egg, milk, peanut, and fish in the pediatric population and could eliminate the need to perform double-blind, placebo-controlled food challenges in a significant number of children.

An exploratory quantitative risk assessment for high molecular weight sensitizers: wheat flour

OBJECTIVE

Quantitative risk assessments have been made for wheat dust and allergen exposure and wheat sensitization using classical epidemiological approaches based on simple categorizations in exposure groups. Such analyses suggest the existence of an exposure threshold level for wheat specific sensitization and were used as input in recently conducted risk assessments for wheat flour by the American Conference of Governmental Industrial Hygienists and the Dutch Expert Committee on Occupational Standards. More advanced statistical analyses were applied using generalized additive modeling and smoothed plots to evaluate the shape of the exposure response relationship in greater detail and evaluate the presence of exposure thresholds.

METHODS

Data were used from a recently conducted epidemiological study in bakery workers. Information was available on wheat sensitization (IgE antibodies), inhalable dust levels and wheat allergen levels. Initial analyses were based on simple exposure categorizations for inhalable dust and allergen exposure. A more detailed analysis using non-parametric generalized additive models (GAM models) and smoothing plots allowed inspection of the presence of an exposure threshold of evaluation of 'no' or 'lowest observed effect levels' (NOELs, LOELs) using exposure data on the individual level.

RESULTS

All analyses showed an increasing sensitization risk with increasing exposure. The classical epidemiological analyses gave evidence for the existence of an exposure threshold or 'no observed effect level (NOEL)' for specific wheat sensitization between 0.5 and 1 mg/m3 of inhalable dust. The more advanced analyses did not suggest any evidence for the existence of an exposure threshold. However, estimates of a LOEL obtained by considering an arbitrary increase in sensitization risk between 1.5 and 2 as undesirable, were close to the NOEL from the classical analyses and would therefore not lead to an essentially different exposure limit. The criterion of an increase in wheat sensitization risk was based on the risk in non-wheat dust exposed populations.

CONCLUSION

Exposure response modeling using different classical epidemiological approaches and advanced statistical methods resulted in health based LOEL or NOEL estimates within a relatively close range. But when sensitization accompanied by asthma or rhinitis symptoms was considered as critical endpoint, steeper exposure-response relationships were observed which would lead to lower LOEL values.

[The developing risks of the allergic child]

6% of infants are allergic to egg. 50% of them are at risk of becoming sensitive to pneumoallergens and of whom 50% develop asthma. These evolutionary risks which are the allergy "course" of the child may be avoided by a precise interrogation which is orientated towards detection by in vitro tests of F x 5 for foods and Phadiatop for pneumoallergens. The responsible allergens may themselves be shown by skin tests, measurement of specific IgE by CAP-RAST made by UNICAP.

Food-dependent exercise-induced anaphylaxis: a report of two cases and determination of wheat-gamma-gliadin as the presumptive allergen

Water/salt-insoluble wheat proteins have been identified as the most frequent allergenic foodstuffs in patients with food-dependent exercise-induced anaphylaxis (FDEIA) in Japan. However, the specific allergenic proteins in wheat-dependent exercise-induced anaphylaxis have not been well defined. Challenge testing, skin testing and a fluoroenzyme immunoassay were used for diagnosis in two patients suspected by history of having wheat-dependent exercise-induced anaphylaxis. Gel chromatography and IgE immunoblotting followed by N-terminal amino acid sequencing were used to identify the allergenic wheat protein. The challenge test revealed that both patients had FDEIA. The skin tests and the immunoassay results suggested that wheat gluten was the allergen in both patients. Gel chromatography of wheat gluten revealed that the antigens had molecular weights ranging from 40 to 250 kDa. IgE immunoblotting and subsequent N-terminal amino acid sequencing revealed that wheat-gamma-gliadin was the antigen predominantly bound by IgE in the two patients.

[A study of food-dependent exercise-induced anaphylaxis by analyzing the Japanese cases reported in the literature]

We surveyed and analyzed cases of food-dependent exercise-induced anaphylaxis (FDEIA) in the Japanese literature. We found 167 cases which were reported as FDEIA since 1983. Analyzing these case, following characteristic features were revealed: 1) Recent upward trend in the number of reports of FDEIA was noted. 2) Male cases were more frequent than female cases, while about half of the cases were teenager. 3) More than half of the cases were proved to be induced by wheat followed by shrimp. In those under 20, shrimp was the most popular cause rather than wheat. 4) Skin test and/or IgE RAST showed positive results in most cases, suggesting that the response itself is linked to type I allergic reaction. 5) About 40% of the patients had history of atopic disease, indicating that atopic condition may play some role in FDEIA. 6) All cases who performed provocation test with aspirin responded to food challenge and/or exercise in combination with aspirin. This indicates that aspirin plays a key provoking factor in FDEIA. 7) In 17 cases FDEIA attacks were observed during noon recess or physical education class after lunch at school. We stress here the importance of a nation-wide education to school teachers the potential danger of this disorder.

What safety measures need to be taken in oral food challenges in children?

BACKGROUND

Food allergens are often accused of causing numerous ailments. This is particularly true for the pediatric population, where the incidence of food allergy is four times as high as in adults. As food challenges may provoke life-threatening reactions, intensive safety measures need to be taken during provocation, and prompt medical intervention may become necessary.

METHODS

We retrospectively evaluated 349 oral challenges in 204 children with atopic dermatitis, looking for criteria to help the physician decide which patients need medical intervention.

RESULTS

A total of 178 (51%) oral food challenges with the four allergens (cow's milk [CM], hen's egg [HE], wheat, and soy) showed a positive clinical reaction. Of these, 120 (67%) needed medical intervention. In 42 (35%) cases, intervention was parenteral, and oral medication was given in 78 (65%) cases. There was a strong positive correlation (90%) between the level of specific IgE and the need for medical intervention (> or = 17.50 kU/l for CM, wheat, and soy; > or = 3.50 kU/l for HE). Patient history of food allergy was an indicator of the need for medical intervention (P = 0.01). A positive patient history and a high level of specific IgE were significantly (P=0.003) associated with parenteral medication in HE.

CONCLUSIONS

Patient history of food allergy is a reliable indicator of the need for medical intervention in the cases of CM, wheat, and soy regardless of the level of specific IgE. With HE, a positive patient history plus a high level of specific IgE significantly indicates the need for parenteral medication. On the basis of our results, we recommend establishing intravenous access in children with a level of specific IgE of > or = 17.50 kU/l (CAP class 4) to CM and wheat, or with specific IgE of > or =3.50 kU/l (CAP class 3) to HE.