Hypersensitivity to aeroallergens in adult patients with atopic dermatitis develops due to the different immunological mechanisms

Atopic dermatitis (AD) is a disease with a complex pathomechanism, it is very difficult to establish the exact factors which can either trigger or exacerbate the disease. Knowledge of the mechanisms involved in AD development can be increased by, among others, applying new diagnostic tests and careful assessment of the results obtained. The aim of this study was to determine the allergic mechanisms of hypersensitivity to selected aeroallergens in patients with AD. The study comprised 109 AD patients. In all the patients the total IgE level was measured and atopy patch tests and skin prick tests were performed. We also assessed the presence of specific IgE against house dust mite, birch-tree, mixed grass pollen and cat dander. The highest incidence of positive results was found for house dust mite allergens, irrespective of the test employed. Analysing hypersensitivity to all the examined allergens we revealed the presence of allergic mechanisms in 85.3% of the patients. In 30.2% of the examined individuals we proved a type I immunological response, in 45.9% -- both types I and IV in 9.2% -- only type IV in one patient. In 14.7% of the patients the results of all the tests performed were negative. Analysing hypersensitivity to particular aeroallergens, negative test results to house dust mite were observed in 25.8% of the patients. The percentage of positive results for birch pollen, grass pollen and cat dander were 45.0, 44.1 and 53.2, respectively. Analysis of the results showed that allergic reactions to the same aeroallergens may develop via different mechanisms. We also revealed that the coexistence of various mechanisms involved in the development of hypersensitivity to a particular aeroallergen may occur in individual patients.     

Allergic contact dermatitis from natural rubber latex in atopic dermatitis and the risk of later Type I allergy

The aims of the study were to assess whether contact dermatitis in children could be due to a delayed hypersensitivity reaction to natural rubber latex (NRL) and to define risk factors for later occurrence of Type I hypersensitivity to this allergen. Among 1800 children investigated for contact dermatitis, 55 were referred on suspicion of rubber allergy and had patch tests to NRL, as well as prick tests and blood tests for specific immunoglobulin E (IgE). A 2-year follow-up was then carried out. Delayed hypersensitivity to NRL was confirmed in 32 children. Patch testing with NRL proved to be positive, and clinical improvement confirmed the diagnosis and relevance of patch tests. 30 of these 32 patients had associated atopic dermatitis (AD). Prick tests and blood tests for specific IgE to latex were negative at the time of diagnosis. A 2-year follow-up showed that 10 of 27 patients presenting initially with a positive patch test without associated Type I sensitization later developed immediate hypersensitivity. Children with AD are at high risk for allergy to NRL protein. Exclusion of this allergen should be strongly advised in atopics because of the dual risk of dermatitis and later evolution into severe Type I hypersensitivity.     

The frequency of contact allergy in atopic patients with dermatitis

A prospective study was performed to establish the frequency of contact allergy in atopic patients presenting with dermatitis, compared with non-atopics suffering from dermatitis. During 1987-1988, all new patients aged 15 years or older, who consulted us for dermatitis, were investigated. They were patch tested with the European standard series, methyl(chloro)isothiazolinone and other relevant allergens. In addition, they were prick tested with 24 inhalant and 11 food allergens. Patients having at least 2 positive prick tests, and patients with 1 positive prick test and a (family) history of atopic diseases were defined as atopics, as were those who presented with classic atopic dermatitis but with negative prick tests. 499 patients were evaluated: 159 men and 340 women. 214 patients (43%) were atopic, the other 285 (57%) were non-atopic. In the atopic group, 79 persons (37%) had at least 1 positive patch test reaction. In the group of non-atopics, 149 patients (52%) had contact allergies. The difference is statistically significant (chi 2; p less than 0.05). It is concluded that adult atopics seen in dermatological practice who present with dermatitis are less frequently contact sensitized than such patients who are non-atopic. Nevertheless, a yield of nearly 40% positive patch test reactions in this group still makes routine patch testing necessary.     

Results of atopy patch tests with house dust mites in adults with ''intrinsic'' and ''extrinsic'' atopic dermatitis

BACKGROUND: The most frequently employed diagnostic criteria of atopic dermatitis (AD) can be fulfilled in the absence of elevated total circulating IgE or specific IgE to food allergens or environmental aeroallergens and/or in the absence of personal or familial history of atopy as well. Therefore a distinction between 'extrinsic' or 'allergic' and 'intrinsic' or 'non-allergic' AD has been suggested. Recently, a patch test with environmental aeroallergens, named atopy patch test (APT), has been proposed for use in the study of AD. OBJECTIVE The aim of this study was to investigate the reactivity to APT in patients with 'extrinsic' and 'intrinsic' AD. PATIENTS, MATERIALS AND METHODS: Two groups of adult male subjects with AD were examined consecutively in our department (Department of Dermatology, Italian Navy Main Hospital, Taranto, Italy) andpatch tested with whole bodies of house dust mites (HDM) at a concentration of 20% in petrolatum (Dermatophagoides pteronyssinus 50%, D. farinae 50%). The groups included: (i) 95 patients affected by the adult clinical form of 'extrinsic' AD; (ii) 12 patients affected by the adult clinical form of 'intrinsic' AD; and (iii) a control group of 49 adult healthy male subjects with a negative anamnesis for eczema and atopy and negative skin prick test to aeroallergens/food allergens and/or normal level of total circulating IgE, also patch tested with the same allergen. The statistical differences were calculated by chi2 test and 95% confidence intervals (CI) were provided. RESULTS: The APT was positive in 47.4% (CI: 37-57%) of'extrinsic'AD, in 66.6% (CI: 41-93%) of'intrinsic' AD and in 12.2% (CI: 3-21%) of healthy subjects. The differences between the two AD subgroups and the control group were statistically significant (P < 0.001). CONCLUSIONS: APT positivity is more frequent in both 'extrinsic' and 'intrinsic' AD than in unaffected subjects. Other studies are needed to confirm our data and to explain why the APT is positive in the 'intrinsic' form.     

The role of contact allergy to aeroallergens in atopic dermatitis

In some patients with atopic dermatitis (AD), delayed-type allergy to aeroallergens, such as house dust mite, can be demonstrated by patch testing. Positive patch tests can be expected only in patients with AD and, in them, only to aeroallergens to which type 1 reactions have also been demonstrated. In an as yet unknown number of such cases, aeroallergens appear to play a role in AD. Studies to date have varied too widely in experimental method and design to allow more definite conclusions to be drawn. It is essential that future studies are standardised with regard to patch test system and designed to include adequate controls and assessment of relevance.     

The diagnostic value of atopy patch testing and prick testing in atopic dermatitis: facts and controversies

We conducted a systematic Medline search of the literature (1998-2008) on the criteria for performing the skin prick test and atopy patch testing (APT) to determine their utility in atopic dermatitis (AD). The skin prick, scratch, and skin patch tests are performed to identify which allergen is causing eczematous skin symptoms in patients with AD, or sneezing, nasal congestion, itchy eyes, wheezing, skin rash, and swelling. Many allergens in foods, drugs, and environmental substances (eg, ragweed and fungus), as well as contact allergens, can elicit eczematous skin reactions after epicutaneous application. Because no gold standard exists for aeroallergen provocation in AD, the APT is currently used to evaluate allergen without comparison with another accurate and reliable method. The APT is presumed to reflect delayed-phase clinical reactions. Even with delayed onset of symptoms (more than 2 hours after food ingestion), APT findings were not consistent among AD children. The APT could be used in children with gastrointestinal reactions to foods as well as AD. After standardization, the APT may provide further diagnostic information in addition to the skin prick test and serum immunoglobulin E values and may be able to evaluate the actual clinical relevance of immunoglobulin E-mediated sensitizations for eczematous lesions. The European APT model used with standardization of allergen concentration and vehicle may provide an important diagnostic tool to select patients for avoidance and for procedures of allergen-specific immunotherapy, but the clinical relevance of positive APT reactions awaits standardized provocation and avoidance testing.     

Immediate- and Delayed-Type Contact Hypersensitivity in Children Older than 5 Years With Atopic Dermatitis: A Pilot Study Comparing Different Tests

Abstract: We conducted a prospective open study of immediate- and delayed-type contact hypersensitivity to food and other allergens in 33 children with atoplc dermatitis (AD). The design of the study was exploratory and not randomized. Various methods for detecting immediate-type hypersensitivity were compared. Thirty-three children age 5 to 15 years with persistent AD were initially enrolled, but 3 dropped out. Nine patients had positive reactions to foods in the patch-scratch tests, four had positive reactions in the skin application food test, and five had positive reactions to foods in the prick tests. Positive reactions to foods were observed in only three patients on the delayed-type patch tests. In all tests, but especially the patch-scratch and prick tests, positive reactions to food allergens were observed without clinically related symptoms. None of these tests gave ideal results. Twenty (67%) of the 30 children had positive reactions to inhalants in prick testing. Fourteen showed positive patch-test reactions with the European standard series (True Test). The most positive reactions were to nickel (9 patients), cobalt, and balsam of Peru. Restrictive measures led to evident improvement of AD only in some children. The results of this study illustrate that food allergy plays only a limited rote in patients with AD age 5 to 15 years. We could not conclude which of the tests would predict which children might benefit from dietary manipulation.     

Atopy patch testing with aeroallergens in patients with atopic dermatitis and controls in Singapore

The role of allergy in atopic dermatitis is controversial. The atopy patch test (APT) has been used to investigate the association between atopic dermatitis and aeroallergen allergy. To determine the proportion of patients with atopic dermatitis with positive patch tests to common local aeroallergens and to compare this to controls with and without respiratory atopy, we performed APT, skin-prick tests (SPT) and IgE radioallergosorbent tests (RAST) on 73 patients with atopic dermatitis and on 38 nonatopic controls (13 with and 25 without respiratory atopy). The allergens used were house dust mite, cat dander, Bermuda grass and German cockroach. Only the APT for house dust mite showed a significant difference between the two groups. APT for house dust mite correlated with the RAST test, while APT for cat fur correlated with the SPT. The APT may be useful to evaluate aeroallergens in atopic dermatitis, but further work is needed to make it more reliable.     

儿童特应性皮炎153例变应原皮试分析

目的探讨儿童特应性皮炎(AD)的病因。方法对153例AD患儿进行了变应原皮试。结果阳性率83.01%,其中吸入组阳性率80.1%,食物组74.6%,二组阳性率差异无显著性。常见的阳性变应原为室内尘土(73.5%)、粉尘螨(70.9%)、多价昆虫(56.9%)、虾(46.4%)、芝麻(40.0%)。年龄3岁以内组、3～7岁组和7岁以上组的吸入组皮试阳性率分别为46.7%,82.9%和85.0%,其差异有显著性(P<0.005)。结论吸入性和食物变应原是儿童特应性皮炎的主要病因之一,吸入性变应原过敏多发生在3岁以上。     

Contact allergy to Dermatophagoides in atopic dermatitis patients and healthy subjects

To compare different house-dust-mite-derived allergenic materials and to correlate the presence of IgE LO Dermatophagoides with patch test results, 313 atopic dermatitis (AD) patients and 100 healthy volunteers (HV) underwent patch tests with: Dermatophagoides Pteronyssimus (DPT) lyophilized purified alpha fraction in buffered saline/glycerol 50% and or in petrolatum (Bayropharm); 540% DPT and 50% Dermatophagoides farinae (DF) whole bodies in petrolatum and petrolatum oil (Allergopharma-Bracco); DPT and DF whole bodies in petrolatum and petrolatum oil (Lofarma). We found 39% positive reactions among AD subjects and 13% in HV The presence of serum-specific IgE did not influence the patch test results. with of AD patch-lest-positive patients and 5 of 13 HV respectively, showed a positive prick less and or RAST lo Dermatophagoides. Similar sensitization rates were observed with the allergenic material from Bayropharm (54% positivities) and Allergopharma-Bracco (51% positivities), whereas the preparations from Lofarma gave a 20% response rate.     

Patch testing and aeroallergen intradermal testing in suspected allergic contact dermatitis, unclassified endogenous eczema and non-atopic chronic urticaria

The purpose of this study was to investigate the significance of contact allergen and aeroallergen sensitization in suspected allergic contact dermatitis (ACD), unclassified endogenous eczema (UEE) and non‐atopic chronic urticaria (NACU). 63 cases of suspected ACD, 140 cases of suspected UEE and 21 cases of suspected NACU were patch tested with the standard series of Beijing Medical University and, if available, suspected materials as is. 22 such cases of ACD, 104 such cases of UEE and 42 such cases of NACU were intradermally tested with common aeroallergens. Patients with non‐allergic skin disease served as controls. 85.7% of the suspected ACD patients, 57.9% of the suspected UEE patients and 52.4% of the suspected NACU patients were positive on patch testing, and the results in 81.0% of the suspected ACD patients and 23.6% of the suspected UEE patients were considered relevant. No patch test reactions in the NACU patients were considered relevant. 27.1% of the suspected UEE patients, 41.3% of the suspected ACD patients and 14.3% of the suspected NACU patients reacted to 2 or more contact allergens. High positive rates on aeroallergen intradermal testing were also found in suspected NACU (69.0%), UEE (49.0%) and ACD (59.1%) patients. These results support the conclusions that patients with allergic skin diseases will develop multiple sensitization, and that early detection and avoidance of sensitizing allergens is necessary. The exact rôle of aeroallergen sensitization in these diseases needs further study.     

Atopy patch test reactions to Malassezia allergens differentiate subgroups of atopic dermatitis patients

BACKGROUND: The yeast Malassezia is considered to be one of the factors that can contribute to atopic dermatitis (AD). OBJECTIVES: To investigate the reactivity to Malassezia allergens, measured as specific serum IgE, positive skin prick test and positive atopy patch test (APT), in adult patients with AD. METHODS: In total, 132 adult patients with AD, 14 with seborrhoeic dermatitis (SD) and 33 healthy controls were investigated for their reactions to M. sympodialis extract and three recombinant Malassezia allergens (rMal s 1, rMal s 5 and rMal s 6). RESULTS: Sixty-seven per cent of the AD patients, but only one of the SD patients and none of the healthy controls, showed a positive reaction to at least one of the Malassezia allergens (extract and/or recombinant allergens) in at least one of the tests. The levels of M. sympodialis-specific IgE in serum correlated with the total serum IgE levels. Elevated serum levels of M. sympodialis-specific IgE were found in 55% and positive APT reactions in 41% of the AD patients with head and neck dermatitis. A relatively high proportion of patients without head and neck dermatitis and patients with low total serum IgE levels had a positive APT for M. sympodialis, despite lower proportions of individuals with M. sympodialis-specific IgE among these groups of patients. CONCLUSIONS: These results support that Malassezia can play a role in eliciting and maintaining eczema in patients with AD. The addition of an APT to the test battery used in this study reveals a previously overlooked impact of Malassezia hypersensitivity in certain subgroups of AD patients.     

Platinum in the environment: frequency of reactions to platinum-group elements in patients with dermatitis and urticaria

The aim of the present paper is to evaluate whether increasing environmental exposure increases the frequency of the positive prick and patch test reactions to certain chlorinated platinum salts in patients with dermatitis and urticaria. 800 consecutive subjects with contact dermatitis (n=749) and urticaria (n=51) were variously patch and prick tested with 30 haptens of a standard series, with aqueous solutions of, respectively, hexachloroplatinic acid (H2[PtCl6]), potassium tetrachloroplatinate (K2[PtCl4]), sodium hexachloroplatinate (Na2[PtCl6]), iridium chloride (IrCl3), rhodium chloride (RhCl3) and palladium chloride (PdCl2), and with 16 common inhalants. 153 workers, variably exposed in a platinum refinery, were patch and prick tested only with solutions containing platinum-group elements at various concentrations and with 16 common inhalants. Platinum-group elements did not elicit positive patch or prick test reactions in non-occupationally exposed subjects. In contrast, in exposed workers, positive patch test reactions at day 2 and at 25 min, respectively, were found in 2 subjects with hand dermatitis and in 2 with urticaria and asthma. 22 out of the 153 workers, 18 of whom had rhinitis, asthma, and urticaria, gave positive prick test reactions to 1 or more salts. Furthermore, on patch and prick testing, 4 cross-reactions between platinum, palladium, iridium and rhodium were demonstrated. In conclusion, the test results demonstrate that the present concentration in the environment does not increase the incidence of reactions to platinum salts in patients with dermatitis and/or urticaria. However, if the average level of environmental platinum exposure approaches those existing in industrial settings in the future, we are going to observe more frequent health effects.     

Patch testing with egg represents a useful integration to diagnosis of egg allergy in children with atopic dermatitis

Our aim was to investigate atopy patch and skin prick test reactions to egg in 85 children with atopic dermatitis, and to evaluate their relevance by performing repeated open challenges with egg. Thirty-one percent of our patients showed an eczematous response to the challenge. Positive reactions to atopy patch and skin prick tests were recorded in 37% and 19%, respectively. Atopy patch test sensitivity proved significantly higher than that of skin prick test (79.6% vs. 46.2%), whereas specificity was lower (81.4% vs. 93.2%). Our data suggest that combined skin prick and patch testing improves screening for egg allergy in affected children, identifying 92% of those who were challenge positive among our patients.     

Can atopy patch tests with aeroallergens be an additional diagnostic criterion for atopic dermatitis?

The complex pathomechanisms underlying skin lesions in atopic dermatitis (AD) result in variations of the clinical picture and frequent diagnostic difficulties. The purpose of this study was to evaluate the usefulness of atopy patch tests (APT) for aeroallergens in the diagnosis of AD. The study involved 115 adult patients with AD and 98 healthy volunteers (the control group). APTs for cat dander allergens, birch pollen, a mixture of house dust mite species and a mixture of 5 grass pollen allergens were applied for both groups. Positive reaction to at least one test allergen was found in 53.9% patients compared to 6.2% in the control group (p<0.001). The most frequent hypersensitivity (45.2%) observed was to house dust mite allergens. Polyvalent allergy to 2-4 allergens was found in 56.5% patients. The specificity of tests exceeded 75%, whereas the sensitivity varied from 18 to 66%. CONCLUSIONS: 1. Atopy patch tests, which are characterised by considerable specificity, confirm the role of polyvalent contact hypersensitivity to aeroallergens in the development of atopic dermatitis. 2. Positive aeroallergen ATP results are observed in the majority of patients and can thus be regarded as an additional diagnostic criterion in atopic dermatitis.     

Mite allergen (Der p 1) levels in houses of children with atopic dermatitis: the relationship with allergometric tests

Several studies, in particular in adult groups, have evaluated the involvement of mites in the pathogenesis of atopic dermatitis (AD). This still remains controversial. The objective of this study was to determine the level of house dust mites (HDMs) in the beds of a group of children with AD and correlate these levels with their allergometric assessment. Forty-one children with AD underwent allergometric tests (prick test, patch test and radioallergosorbent test, RAST) and the concentration levels of HDMs in their homes were evaluated. Our data show that about half of the children (51%) with AD presented Dermatophagoides pteronyssinus positivity (prick test and/or RAST and/or patch test). Dust was collected in the period October-November from the children's beds, by the same two operators, using a dust-collection device. The dust mite level was tested by an enzyme-linked immunosorbent assay with antibody against Der p 1 allergen. Ten children (24%) presented a Der p 1 concentration > 2 microgram/g of dust (the value assumed to be a risk level for sensitization), 20 (49%) between 0.1 and 2 microgram/g and 11 (27%) < 0.1 microgram/g of dust. In the group with the highest Der p 1 concentration (> 2 microgram/g dust) nine children (90%) presented an allergometric D. pteronyssinus sensitivity, the difference with the other two groups being statistically significant at P < 0.018. The results of the present study show that the highest HDM concentrations were observed in the group with an allergometric D. pteronyssinus positivity (prick test and/or RAST and/or patch test). It is hypothesized that a higher HDM concentration may elicit D. pteronyssinus IgE sensitization and delayed hypersensitivity in children with AD.     

Compositae sensitivity among patients with contact dermatitis

Patch tests with 24 Compositae species were performed on 81 patients suspected of having a plant dermatitis, of whom 16 had positive reactions to various species. When Compositae were included in the standard series, 10 of 488 consecutive patients (2%) were found to be sensitive to one or more species. Most of the positive test reactions were relevant. Fourteen of 16 sensitivities could have been detected by testing with two mixtures of Compositae. Alantolactone could not serve as a screening agent, since four of seven Compositae-sensitive patients had negative reactions to it. Concomitant reactions to balsams were found in four of 10 patients with unexpected sensitivy to Compositae. The clinical pattern of Compositae dermatitis may be that of a lichenified photo dermatitis. These cases are invariably missed, unless patch tests with Compositae are performed. Another group of patients have hadn eczema and also require patch tests with Compositae for etiological diagnosis. Because positive, relevant reactions are common, inclusion of a safe and reliable Compositae screening test in the standard series is urgently required. At the present stage, however, our test materials are sometimes irritant and they have occassionally caused active sensitization.     

Which aeroallergens are associated with eczema severity?

We investigated if a correlation exists between aeroallergen sensitization and the severity of eczema. Data on aeroallergen response to skin-prick testing (SPT) and disease severity of children with eczema (n = 119) were evaluated. Atopy, as defined by at least one positive response to aeroallergen skin prick testing, was found in > 90% of eczema patients. House dust mite was the most commonly sensitized aeroallergen, followed by cat fur. Dermatophagoides pteronyssinus and Dermatophagoides farinae sensitization were associated with eczema severity (present in 67% of the mild and 97% of the severe group; P = 0.001). However, there was no association between eczema severity and higher strengths of SPT response (defined as SPT > 1+ to dust mites or dust). Atopy to moulds, Bermuda grass, cockroach, cat and dog was less prevalent and was not associated with eczema severity. It is sensible to advise parents on specific avoidance strategies only in severely affected children who have a definitive history of eczema exacerbation by specific aeroallergens and who are not responsive to conventional treatment.     

Occupational dermatitis in Danish gardeners and greenhouse workers

The aim of the study was to assess the distribution of different types of occupational eczema among employees in floristry and detect the allergens most commonly involved. Based on a postal questionnaire, 253 gardeners and greenhouse workers with occupational skin symptoms and 52 randomly-selected without symptoms were examined and patch tested. Routine tests comprised the standard series, the Compositae mix, feverfew and 3 fungicides, with additional testing based on case records. 184 persons from the symptom group and 1 from the random group had occupational eczema. Irritant occupational contact eczema was suspected in 150 persons (59%). Nevertheless, 48% of the 250 persons patch tested had at least 1 positive reaction, most frequently to nickel, followed by Compositae which were positive in 25 cases (10%), of whom 24 were possibly occupationally sensitized. 13 persons from symptom group had positive reactions to fungicides. Occupational allergic eczema was suspected in 43 persons (17%), most often caused by plants belonging to the Compositae, Geraniaceae and Liliaceae families. New plant sensitizers were Exacum affine and Begonia lorraine. Exposure to specific plant species seemed to be the most important eliciting factors in both allergic and irritant occupational dermatitis in floristry, and preventive measures should include reduction of contact with plants.     

Sensitization to cockroach allergens evaluated by skin tests in children with atopic dermatitis

INTRODUCTION: Cockroach and house dust mites (Dermatophagoides pteronyssinus, Dp and farinae, Df) are the most often implicated aeroallergens in severe asthma, hay fever and conjunctivitis. Cockroach allergy is still unknown in atopic dermatitis.PATIENTS AND METHOD: 146 children with atopic dermatitis-aged 6 months to 15 years- have been patch tested with the European standard series and some aeroallergens. We have studied the sensitisation to cockroach allergens and compared to Dp and Df.RESULTS: 113 children reacted positively at least to one of the 3 aeroallergens (77 p. 100), 61 children had a positive reaction to cockroach (42 p. 100) and 29 simultaneously to the 3 allergens.DISCUSSION: Delayed hypersensitivity to house dust mites in young children with atopic dermatitis suggests early epicutaneous sensitization due to an altered epidermal barrier. For us, cockroach could also be implicated in some flare-ups of atopic dermatitis. Eviction of cockroach and house dust mite should be proposed for children with a positive patch test to cockroach.