Comparison of different immunochemical methods for the detection and quantification of hazelnut proteins in food products.

Hazelnuts are widely used in the food industry owing to their nutritive value and taste. The amount of hazelnut present in a recipe is usually considered as a mark of quality. On the other hand, contamination of foods that normally do not contain hazelnuts is a threat for patients with a hazelnut allergy. For this reason, the availability of a method for the detection and quantification of hazelnuts in foods would be desirable. The objective of this study was to develop a method for the detection and quantification of minor amounts of hazelnut protein in food products that is potentially applicable for the food industry. Several immunochemical methods, e.g., immunoblotting and enzyme-linked immunosorbent assay (ELISA), were developed with antibodies from both hazelnut-sensitized patient sera and the sera of rabbits hyperimmunized with hazelnut protein. Immunoblotting appeared to be non-specific when the sera of patients were used as a source of antibodies. Using immunopurified antibodies from rabbits immunized with hazelnuts, immunoblotting became specific, but the sensitivity of this method was limited. Inhibition of IgE binding is a generally used test in clinical laboratories to establish contamination with hazelnuts. This approach is sensitive and specific, but not readily accessible for the food industry since patient serum is needed. Similar results in terms of sensitivity and specificity were obtained with a sandwich ELISA constructed with an immunopurified antibody from rabbits sensitized to hazelnuts. No substantial cross-reactivity with other nuts, legumes or other food constituents was observed, and concentrations as low as 5 ng/ml, corresponding to 1 ppm in food products, were detected. In a field test, several consumer products regarded to be free of hazelnuts were shown to contain traces of hazelnut. This sandwich ELISA constructed with immunopurified antibodies from rabbits sensitized with hazelnut protein is a sensitive and specific method to detect and quantify hazelnut and is useful in detecting trace contamination with hazelnut in various consumer products. Since this test does not require serum from patients, it is appropriate for use in the food industry.

[Immunology in medical practice. V. Constitutional eczema]. / Immunologie in de medische praktijk. V. Constitutioneel eczeem.

Constitutional eczema (late atopic dermatitis) is a frequent condition: some 30% of the skin diseases seen by the GP involve constitutional eczema. A number of links with (external) factors have meanwhile been established. Patients with constitutional eczema often suffer from food allergy (over 60% of the children with the eczema) and many are allergic to airborne allergens (especially housedust mite allergen). The skin of patients with constitutional eczema has a diminished barrier function against irritants (soaps, acids, bases, water, detergents, biological juices (fruit, meat, fish, vegetables). In 90% of the patients with constitutional eczema the skin contains colonies of Staphylococcus aureus (in 5% of people without eczema). S. aureus can influence the eczema through exoantigens (so-called superantigens) and through conventional antigens that may evoke an IgE-mediated immune response. Emotional stress may influence the eczema. The close anatomical relationship between mast cells and nerve endings and between Langerhans cells and nerve endings suggest that the autonomous nervous system can modulate the immune system of the skin and consequently, the eczema. These factors should be taken into account in the treatment: reduction of exposure to food and airborne allergens and to irritants, treatment and prevention of S. aureus infections and psychological support. New therapies include cyclosporine, autologous IgG antigen complexes and phototherapy.

Clinical improvement after unusual avoidance measures in the home of an atopic dermatitis patient.

A 27-year-old female office clerk with widespread atopic dermatitis (AD) since infancy appeared to be highly sensitized and exposed to molds, storage mites, and chicken feathers and moderately sensitized to house-dust mites and grass and birch pollens. Hardly any textiles were present in her home; that is, only 28 m2, which is less than 25% of the Dutch national average. The causal relationship between eczema and molds plus storage mites in this case of AD was strengthened by the positive effect of an unusual, multidisciplinary home-sanitation program involving cleaning of mineral surfaces and ventilation improvement. This home-sanitation program led to a gradual drop of total IgE and clinical symptom scores to 21% and 13%, respectively, of the original values.

IgE antibodies to Pityrosporum ovale in atopic dermatitis.

An enzyme-linked immunosorbent assay (ELISA) was developed to assess serum IgE antibodies directed against Pityrosporum ovale in patients with atopic dermatitis (AD), atopic patients with allergic respiratory disease (ARD: rhinitis or asthma) but without eczema, and in healthy controls. IgE binding to P. ovale extract was demonstrated in 49% (35/72) of AD patients. In contrast, anti-P. ovale IgE was found in only one of 27 atopic controls without eczema; all healthy control sera (n = 17) were negative. Of 37 AD patients tested intracutaneously with P. ovale, 31 showed immediate-type reactivity, and 20 of these 31 patients had anti-P. ovale IgE detectable by ELISA, while sera from the six non-responders were all negative. Levels of anti-P. ovale IgE were highest in AD patients aged 20-30 years. No correlation was found with the severity of AD, but there was a non-significant tendency (P = 0.06) to higher levels in AD patients with concomittant respiratory allergy. Anti-P. ovale IgE was significantly correlated with total serum IgE, with specific IgE against various aeroallergens as measured by RAST, and with levels of anti-Candida albicans IgE, measured with a similar ELISA. Thus, production of IgE antibodies against P. ovale occurs very frequently in AD, and rarely in patients with atopic disease without skin involvement.

Clinical evaluation of a double-blind dust-mite avoidance trial with mite-allergic rhinitic patients.

Inheritance and allergen exposure are key factors in the development and the course of atopic allergy, expressed as conjunctivitis, rhinitis, asthma or dermatitis. This study concerns the clinical significance of mite and mite-allergen avoidance measures based on intensive cleaning with acaricide (solidified benzylbenzoate) added (10 dwellings), and without biocidal activity (10 other homes) as a control in a double-blind trial with matched pairs. Twenty subjects with persisting rhinitic complaints were selected. They lived in 20 different dwellings and were all sensitized to pyroglyphid mites; 12 of them were also sensitized to stored product mites (Acari). Daily symptoms and medication score, guanine and dust exposure, total and mite-specific IgE in serum, eosinophilia in the blood and in the nasal smear, intracutaneous tests with house dust mite and storage mite extracts were compared in both pairs and groups. Acarological data, physiochemical aspects and exposure assessment are discussed in detail elsewhere. Symptom scores dropped significantly, as did the total IgE and exposure to dust and mite products in the acaricidal cleaner treatment group. After 1 year, the daily symptoms median was 47% (P = 0.025), total IgE was 38% (P = 0.0049), and exposure to dust and mite products (guanine exposure) was 53% (P = 0.0449) better or lower than in the controls. Intensive cleaning, without acaricidal treatment performed twice a year, resulted in clinical improvement in four out of 10 subjects, of whom none became free of complaints. In the Acarosan treatment group (cleaning + benzylbenzoate) eight out of 10 subjects improved, in three cases subjective symptoms disappeared.(ABSTRACT TRUNCATED AT 250 WORDS)

Cross-reactivity among the pollen proteins of birch and apple trees.

In the spring of 1986, the pollen were collected from apple trees in full blossom, and were investigated for their allergenicity. The patients selected for study were subjects with a combined inhalant allergy to birch pollen and an oral allergy to apple fruit. The apple pollen extract yielded about the same percentage of nondialysable substance as obtained from birch pollen. In contrast to the latter, UV-spectroscopy revealed no flavonoids adsorbed to the apple pollen proteins. Patients with a combined allergy to birch pollen and apple fruit showed positive skin reactions to both birch and apple pollen extract. Inhibition of IgE-binding in RAST to birch pollen was observed by apple pollen extract at a 1000-fold lower potency than the homologous birch allergens. Immunoblotting demonstrated IgG-antibodies in birch-allergic sera cross-reactive with apple pollen components. It is concluded that minor allergenic determinants cross-reactive with birch pollen epitopes occur not only in the fruit, but also in the pollen of the apple tree.

Intracutaneous tests with pityrosporon extract in atopic dermatitis.

In patients with atopic dermatitis and in a control group prick and intracutaneous tests were performed with Pityrosporon extracts. Moreover, specific IgE against Pityrosporon was determined in these patients. Significant differences existed between the results obtained with these methods in both groups of patients. Therefore, both skin tests with Pityrosporon extract and IgE determinations may contribute to a diagnosis of AD; moreover, it is likely that Pityrosporon may be of significance in the pathogenesis of AD.

Blood groups ABO and grass-pollen hayfever.

The frequency distribution of the blood group phenotypes ABO was examined in retrospect in a selected group of 241 Patients with grass pollen hayfever. A relative deficiency in blood group O was found, with a shift toward an over-represented B-phenotype as compared to the general population. This shift appeared to be largely due to the contribution from the female patients with pollinosis. Comparison with literature data confirmed a lower frequency of the O-phenotype in atopic patients in general, irrespective of the specific sensitivities.

Cow's milk allergy in an adult patient.

A 22-year-old female patient is described who was repeatedly hospitalised on account of severe asthmatic attacks presumably due to the ingestion of cow's milk or milk-containing products. There were no signs of gastrointestinal disturbance, but some urticaria and angioedema occurred. Strongly positive RASTs were observed in the blood serum against the proteins in cow's milk, bovine serum, egg white, cod fish, and house dust. The symptoms were successfully controlled by rigorous dietary measures.

Animal dander allergy.

In a group of twenty-three atopic patients skin tests were performed with the dander allergens of horse, cat and guinea-pig, and with house dust and Timothy pollen allergens. A good agreement was observed between positive skin reactions and the results of RAST with these various allergens. In a number of cases, positive skin reactions were not related to the clinical histories. Likewise, positive RAST scores in several instances proved clinically meaningless. In patients with history-related skin reactions better correlation with RAST was observed. In such patients, skin reactions with photo-inactivated allergens remained strongly positive.

Specific and non-specific skin test reactions with animal dander extract.

Intradermal skin tests have been performed in atopic patients with allergenic extracts of different animal danders at uniform concentration. A high incidence of positive test was recorded which could not be related to the clinical histories, especially with the allergens of horse, cow and dog dander (NR). Better correlation was observed with guinea pig and cat allergens (R). The incidence of NR reactions was highest in the house dust allergy group of patients; with the exception of horse dander allergen, the frequency of R reactions was more pronounced in the grass pollen group. It is suggested that both allergen-specific and non-allergen-specific mechanisms may contribute to positive wheal and flare reactions.