Combination of patch test and IgE for dust mite antigens differentiates 130 patients with atopic dermatitis into four groups

Classifying atopic dermatitis: a systematic review of phenotypes and associated characteristics

Atopic dermatitis is a heterogeneous disease, accompanied by a wide variation in disease presentation and the potential to identify many phenotypes that may be relevant for prognosis and treatment. We aimed to systematically review previously reported phenotypes of atopic dermatitis and any characteristics associated with them. Ovid EMBASE, Ovid MEDLINE and Web of Science were searched from inception till the 12th of February 2021 for studies attempting to classify atopic dermatitis. Primary outcomes are atopic dermatitis phenotypes and characteristics associated with them in subsequent analyses. A secondary outcome is the methodological approach used to derive them. In total, 8,511 records were found. By focusing only on certain clinical phenotypes, 186 studies were eligible for inclusion. The majority of studies were hospital-based (59%, 109/186) and cross-sectional (76%, 141/186). The number of included patients ranged from seven to 526,808. Data-driven approaches to identify phenotypes were only used in a minority of studies (7%, 13/186). Ninety-one studies (49%) investigated a phenotype based on disease severity. A phenotype based on disease trajectory, morphology and eczema herpeticum was investigated in 56 (30%), 22 (12%) and 11 (6%) studies, respectively. Thirty-six studies (19%) investigated morphological characteristics in other phenotypes. Investigated associated characteristics differed between studies. In conclusion, we present an overview of phenotype definitions used in literature for severity, trajectory, morphology and eczema herpeticum, including associated characteristics. There is a lack of uniform and consistent use of atopic dermatitis phenotypes across studies.

Comparison of atopy patch testing to skin prick testing for diagnosing mite-induced atopic dermatitis: a systematic review and meta-analysis

BACKGROUND

Atopic dermatitis (AD) can occur after contact with aeroallergens like house dust mites, pollen, and animal dander. Despite its controversial diagnostic value, the atopy patch test (APT) has been used as an important tool in the diagnosis of AD caused by house dust mites. Here, we present a meta-analysis comparing APT to the common skin prick test (SPT) in the diagnosis of mite-induced AD.

METHODS

A structured search was performed using online databases and bibliographies published as of April 30, 2017. All studies evaluating the accuracy of APT and SPT in the diagnosis of mite-induced atopic eczema/dermatitis syndrome were selected, appraised, and data was extracted.

RESULTS

Ten studies were identified for inclusion in our analysis. Meta-analysis revealed that the pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratios for APT were 0.54 (95% CI 0.42-0.66), 0.72 (95% CI 0.56-0.85), 1.97 (95% CI 1.20-3.23), 0.63 (95% CI 0.48-0.83), and 3.12 (95% CI 1.53-6.39). The area under the summary receiver operating characteristic curve was 0.65 (95% CI 0.61-0.69).

CONCLUSIONS

Our analysis indicates that APT is a useful tool in the screening of mite-induced AD, although this conclusion must be interpreted cautiously due to high heterogeneity among the included studies.

Patch testing for noncontact dermatitis: the atopy patch test for food and inhalants

The atopy patch test (APT) is defined as a patch test procedure to assess delayed type hypersensitivity reactions against those protein allergens known to elicit IgE-mediated type I reactions in atopic patients. This patch test procedure uses intact protein allergens instead of haptens in an optimized test setting and with a special reading key. It may be clinically useful especially for atopic dermatitis, as the currently available test procedures either target the wrong reaction type (type I and not type IV) or use the wrong allergens (haptens and not protein allergen). A positive APT reaction correlates with a positive lymphocyte transformation test and allergen-specific Th2 cells in the peripheral blood. As even small changes in the test procedure influence the sensitivity, specificity, and reproducibility of the APT, the European Task Force on Atopic Dermatitis (ETFAD) has developed a standardized APT technique: Intact protein allergens, purified in petrolatum, are applied in 12-mm-diameter Finn chambers mounted on Scanpor tape for 48 h to non-irritated, non-abraded, or tape-stripped skin of the upper back for 48 h; the evaluation of the test reaction is done after 48 and 72 h using the ETFAD reading key, assessing erythema as well as number and distribution pattern of the papules. The APT may reveal type IV sensitization in patients who are negative for the respective type I tests. Limited availability of the expensive test substances and limited reimbursement is among the factors restricting the routine use of the APT.

Immunoglobulin e-mediated allergy plays a role in atopic eczema as shown in the atopy patch test

Although the pathophysiology of immunoglobulin E (IgE)-mediated allergic rhinoconjunctivitis and bronchial asthma is rather well established, the role of allergy in atopic eczema (AE) is still controversial. By a technique called atopy patch test, aeroallergens like house dust mite, animal dander, or pollen were proven as relevant trigger factors in a subgroup of patients with AE. The atopy patch test is an epicutaneous patch test with such allergens known to elicit IgE-mediated reactions, and used for the evaluation of eczematous skin reactions. In a series of single-center and multicenter studies, a method was developed, standardized, and compared with other diagnostic techniques (radioallergosorbent test, skin prick test) in AE patients. With regard to clinical history, the most specific results were obtained with the atopy patch test (allergen-dependent, 69%-92%), whereas sensitivity was higher for skin prick test (range, 69%-82%) and specific IgE (range, 65%-94%). The characterization of a patient subgroup with relevant IgE-mediated allergy may lead to more efficient avoidance and eventually even specific immunotherapy strategies in the management of AE.

Patch testing with dermatophagoides and its correlation with chronic eczema and atopic dermatitis

Background:

Chronic eczema is commonly encountered in the Indian set up. So also is atopic dermatitis. House dust mites (Dermatophagoides) are implicated in various diseases like atopic dermatitis, asthma, and perennial rhinitis. It has also been proven that patch testing with Dermatophagoides pteronyssinus (DP) is important for detection of contact sensitization in chronic dermatitis.

Aims:

To study clinical characteristics of DP mix positive patients with regards to chronic dermatitis and atopic dermatitis.

Methods:

Dermatology outpatients presenting to the department of Skin and STD of Kasturba Medical College (KMC), with clinically diagnosed atopic dermatitis and chronic eczema were chosen for the study. Inclusion and exclusion criteria were well demarked. Eighty six randomly selected patients of dermatitis were subjected to patch testing with standard series and DP mix.

Results:

Of the 86, 50 (58%) showed positive reaction to DP mix. Among these positive patients, chronic dermatitis was seen in 42 (84%) with involvement of exposed parts in 37 (74%). Atopic dermatitis was seen in 19 patients (38%) from DP positive group whereas it was observed in 4 patients (17%) from the other group.

Conclusion:

Dermatophagoides mix positivity was statistically significant in chronic eczema as well as atopic dermatitis. Patch testing is an important tool to detect delayed type allergy to house dust mite.

The role of atopy patch tests in the diagnosis of allergy in atopic dermatitis

PURPOSE OF REVIEW

Recent literature on the atopy patch test, published since 2004, is reviewed to evaluate whether the pathomechanism of the test has become more evident and whether previous studies require standardization.

RECENT FINDINGS

There is evidence accumulating that a smaller subset of patients with atopic dermatitis show only atopy patch test positivity while specific IgE to the same allergen remains negative. It is possible that local IgE-mediated reactions occur in the skin. New data bring us a step forward in understanding the role of the atopy patch test in diagnosis of allergy in atopic dermatitis but no comprehensive studies were published during the period reviewed.

SUMMARY

Despite recent advances in determining the value and indication for use of the atopy patch test in atopic dermatitis, more objective studies are needed. The atopy patch test may be useful in understanding the mechanisms of atopic allergy, and in defining the clinical relevance of the airborne allergens in eliciting dermatitis. Regarding food allergy, the atopy patch test still requires standardization. To date, methodology differs in all published papers; even the gold standard, the challenge test itself, is not appropriately standardized, which makes the interpretation of results less reliable.

Lessons from atopy patch testing in atopic dermatitis

The exposure of atopic eczema (AE) patients to their relevant protein allergens (eg, from house dust mite, cat dander, grass pollen, or food allergens) can trigger an exacerbation or maintain the disease. Diagnostic procedures are needed to specify allergen avoidance recommendations for the individual patient. Skin prick tests and specific serum IgE tests might be helpful in pointing out potential trigger factors, but relevance needs to be confirmed (eg, with food provocation tests). The atopy patch test (APT) involves the epicutaneous application of intact protein allergens in a diagnostic patch test setting with an evaluation of the induced eczematous skin lesions after 24 to 72 hours. The APT targets the cellular component of AE and helps round out the AE test spectrum. As a number of apparently minor test modifications greatly influence the sensitivity, specificity, and reproducibility of the APT, the European Task Force on Atopic Dermatitis (ETFAD) has developed a standardized APT technique. It consists of purified allergen preparations in petrolatum, applied in 12-mm diameter Finn chambers mounted on Scanpor tape to non-irritated, non-abraded, or tape-stripped skin of the upper back. The APT is read at 48 and 72 hours according to the test criteria and reading key of the ETFAD for appearance of erythema, and number and distribution pattern of the papules. In contrast with skin prick tests, the APT might even detect a relevant sensitization in the absence of specific IgE. Many studies have been undertaken to objectify the sensitivity and specificity of the APT to show its diagnostic use in clinical practice.

Atopy patch test in patients with atopic eczema/dermatitis syndrome: comparison of petrolatum and aqueous solution as a vehicle

BACKGROUND

The atopy patch test (APT) is an in vivo model to study the induction of eczema by inhalant allergens. This study was designed to compare two commonly used APT methods.

METHODS

In the first method, the allergen is dissolved in aqueous solution, which is applied on tape-stripped skin. In the second method, the allergen is dissolved in petrolatum and applied without tape stripping. Thirteen patients with atopic dermatitis sensitized to inhalant allergens were patch tested using both methods. Reactions were evaluated macroscopically and microscopically after 48 h.

RESULTS

Nine out of 13 patients displayed a positive reaction for both methods. One patient had a positive APT for the aqueous method alone and three for the petrolatum method alone. Reactions were significantly stronger when using the petrolatum method. Histological evaluation of the nine patients positive for both methods showed no significant differences in number of eosinophils, T-cells and neutrophils.

CONCLUSION

The APT using the petrolatum vehicle induces a higher number of positive reactions and is significantly stronger relative to the APT using allergen in aqueous vehicle. The cellular influx in both test methods is comparable. Both methods can be used to study the mechanisms in the induction of eczema by inhalant allergens.

[Atopic patch test. Atopic eczema and allergy]

The role of IgE-mediated allergic reactions in atopic eczema remains controversial. Using the atopy patch test, aeroallergens such as house dust mites, animal dander or pollen can be identified as relevant trigger factors in a subgroup of patients with atopic eczema. The atopy patch test is an epicutaneous patch test employing allergens known to elicit IgE-mediated reactions and used to evaluate eczematous skin reactions. In a series of single- and multicenter studies, a method was developed, standardized and compared to other diagnostic techniques (specific serum-IgE, skin prick test) in atopic eczema patients. With regard to clinical history, the most specific results were obtained with the atopy patch test (allergen-dependent 69-92%), while sensitivity was higher for skin prick test (69-82%) and specific IgE (65-94%). The characterization of a patient subgroup with relevant IgE-mediated allergy may lead to more efficient avoidance and perhaps even specific immunotherapy strategies in the management of atopic eczema.

Frequency and intensity of responses to mite patch tests are lower in nonatopic subjects with respect to patients with atopic dermatitis

BACKGROUND

So far the issue of patch tests with mite allergens in subjects not affected by atopic dermatitis (AD) has been poorly investigated. The aim of this study was to assess the frequency and intensity of responses to atopy patch tests with Dermatophagoides in non-AD subjects, and to compare them to the ones observed in AD patients.

METHODS

Patch tests were performed, employing a mixture of Dermatophagoides pteronyssinus and farinae at two different concentrations (20 and 40% pet.), on 75 non-AD subjects, including 33 patients with allergic rhinitis and 42 healthy volunteers, and on 210 AD patients, as controls.

RESULTS

Positive responses to 20% mite patch tests were observed in 17 non-AD subjects (23%) and in 102 AD ones (49%). The former showed a lower intensity of the responses, with a mean score of 1.4 compared with 2.1 in atopics.

CONCLUSIONS

Although positive responses to mite patch tests are also observable in subjects without AD, their frequency and intensity are significantly lower compared with AD patients.

Application of human Fc epsilon RI alpha-chain-transfected RBL-2H3 cells for estimation of active serum IgE

We transfected the alpha-chain of human FcepsilonRI into rat basophilic leukemia cell line RBL-2H3, established several stable transfected cells, and screened them by beta-hexosaminidase release induced by sensitization with human IgE and stimulation with anti-human IgE antibody. A cloned cell line RBL-hEIa-2B12 was the strongest responder among the transfected cell clones. The concentrations of cytosolic free Ca2+ concentration in the human IgE-sensitized cells increased after stimulation with anti-human IgE antibody. Thus, it is suggested that the alpha-chain of human FcepsilonRI is associated with the beta-chain and/or gamma-chain of rat FcepsilonRI, and that they form functional high affinity IgE receptor complexes. The total IgE concentrations of the sera from allergic patients were determined by using the beta-hexosaminidase release assay, where the transfected cells were sensitized with diluted and heat-inactivated (at 56 degrees C for 30 min) serum and stimulated with anti-human IgE antibody. The IgE concentration obtained correlated with those measured by an enzyme immunoassay method. beta-Hexosaminidase release induced by stimulation with 5 times diluted serum was sometimes less than the release induced by the same serum; diluted 25 times or 125 times, suggesting that these serum contained factors that blocked IgE binding to FcepsilonRI or cross-linking by anti-human IgE antibody. The results suggested that our system will be useful for detecting FcepsilonRIalpha-bindable IgE in human serum.

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.

Cutaneous late phase reaction in adult atopic dermatitis patients with high serum IgE antibody to Dermatophagoides farinae: correlation with IL-5 production by allergen-stimulated peripheral blood mononuclear cells

It is known that, in patients of allergic asthma and rhinitis, the late-phase reaction (LPR) occurs 6-12 h after allergen challenge, but there are few reports concerning cytokine production in the cutaneous LPR in atopic dermatitis (AD). We report here the results of our study on the relationship between the cutaneous LPR and the production of cytokines such as IL-4, IL-5, IL-2 and IFN-gamma by peripheral blood mononuclear cells (PBMC) of AD patients. We selected 29 pure AD patients with no history of atopic airway diseases who showed high serum IgE antibody against Dermatophagoides farinae and performed skin prick testing with three different antigens and observed the resultant cutaneous reactions in 23 of the AD patients. Furthermore, we measured the cytokine production by the cultured PBMC under the stimulation of the antigens and compared it with the results of the skin tests. 13 (57%) of these 23 AD patients demonstrated positive LPR in response to D. farinae, and the mean concentration of IL-5 produced by PBMC was higher in these LPR-positive AD patients compared to the LPR-negative ones. Additionally, we noticed that there was a positive correlation between the mean diameter of the erythema of LPR and the level of IL-5 production by PBMC in the LPR-positive patients. We suggest that there are at least two groups in AD patients, i.e. LPR-positive and LPR-negative ones. The observation of LPR can be an important and practical way to classify AD patients into subgroups, which may enable us to regard IL-5 or eosinophils as a target for treatment.

[Role of aeroallergens in the etiopathogenesis of atopic dermatitis]

Atopic dermatitis is a chronic relapsing inflammatory skin disease. It is most frequent in childhood and its clinical manifestations vary with age. The etiopathogenic mechanisms that explain this process are still poorly understood; several studies performed in adults speculate on the possible role of aeroallergens through direct contact with the skin but, because the etiology of this disease varies with age, studies in children of different ages are required.

AIMS

(i) To determine whether children with atopic dermatitis are sensitized to inhalant allergens. (ii) To determine whether these inhalant allergens cause dermatitis or whether they provoke allergic respiratory disease (asthma, rhinitis) concomitant with atopic dermatitis. (iii) To evaluate whether sensitization to a particular allergen takes place at any age or whether there are differences according to age.

MATERIAL AND METHODS

This study was performed in the following groups: (i) 64 children with atopic dermatitis, divided into two subgroups, one consisting of 37 children who also presented allergic respiratory disease (asthma, rhinitis) (AR) and another subgroup of 27 patients who presented atopic dermatitis only. (ii)

CONTROL GROUP

eight children who presented AR only, to determine whether this group reacted to patch testing with inhalant allergens. (iii)

CONTROL GROUP

seven healthy children to rule out non-specific positive tests in the non-atopic population. All groups were divided by age according to the phases of atopic dermatitis: early childhood phase (< 2 years): 21, childhood phase (2-10 years): 37, adolescent phase (> 10 years): 21. In all children total serum IgE determination (RIA), allergen-specific IgE determination (RAST), prick- and patch test were performed. In the three tests the same allergens were used, consisting of the usual components of standardized inhalant and food allergens. When the results of patch testing were positive, biopsy and histopathological analysis were performed and monoclonal antibodies were used to determine reproducibility of the eczematous lesion.

RESULTS

Sensitization was found to differ among patients with atopic dermatitis according to whether they presented respiratory symptoms and according to age with a clear predominance of food sensitization in the group aged less than 2 years. In the group aged 2-10 years, mixed sensitization predominated, mainly because of simultaneous respiratory involvement, but it is highly probably that inhalant allergens participate in the etiopathogenesis of atopic dermatitis. In children aged more than 10 years sensitization to inhalant allergens predominated as most presented respiratory symptoms. Patch testing was positive in 34.3 % of patients with atopic dermatitis and approximately half were positive to dust mites. The patch test is of great diagnostic value in atopic dermatitis and none of the tests were positive in the control group. All the biopsies of patch tests with inhalant allergens reproduced the lesions typical of eczema, demonstrating their involvement in the etiopathogenesis of dermatitis.

TGF-beta-producing CD4+ mediastinal lymph node cells obtained from mice tracheally tolerized to ovalbumin (OVA) suppress both Th1- and Th2-induced cutaneous inflammatory responses to OVA by different mechanisms

Advances in the treatment of allergic disorders require elucidation of the autoregulatory immune systems induced in averting detrimental inflammatory responses against invading foreign Ags. We previously reported that excessive Ags intruding through the airway mucosa induce a subset of regulatory CD4+ T cells secreting TGF-beta in the regional mediastinal lymph nodes (MLNs), which inhibits Th2 cells and subsequent eosinophilic inflammation in the trachea. In the present experiments we examined whether and in what mechanisms TGF-beta-secreting CD4+ T cells in the MLNs regulate Th cell-mediated skin inflammation using a previously established murine model. Th1 or Th2 cells injected s.c. into ear lobes of naive mice induced swelling, whereas the concomitant local injection of MLN cells suppressed the inflammation. The suppressor activities of MLN cells were markedly neutralized by anti-TGF-beta mAb and were mimicked by rTGF-beta. The MLN cell- and rTGF-beta-induced inhibition was reversed by anti-IL-10 mAb significantly in Th1-induced inflammation and only partially in Th2-induced inflammation. rIL-10 reduced Th-induced ear swelling, although higher doses of rIL-10 were required in Th2-induced one. Thus, allergen-specific TGF-beta-producing CD4+ T cells induced in the respiratory tract controlled cutaneous inflammatory responses by Th1 or Th2 cells either directly by TGF-beta or indirectly through IL-10 induction. From a clinical standpoint, these observations might explain the mechanism of spontaneous regression in some patients with atopic dermatitis, which exhibits both Th1- and Th2-mediated skin inflammation in response to airborne protein Ags.

Clinical characteristics of mite allergen specific-lymphocytes stimulation test-positive Japanese cases with adult type atopic dermatitis

To identify the correlation between the house dust mite-specific lymphocytes proliferation and other clinical parameters and clinical features, we conducted a lymphocytes stimulation test in 37 patients with atopic dermatitis. A total of 12 patients showed positive reactions (positive patients) and 25 showed no reaction (negative patients). Both the number and percentage of peripheral blood eosinophils were significantly lower in positive patients than in negative patients. Stimulation index measured by lymphocytes stimulation test showed no correlation with the total IgE level, nor the number and percentage of eosinophils. Stimulation index weakly correlated with mite-specific IgE-RAST scores both in positive patients and in negative patients. Only in positive patients, stimulation index weakly correlated with the severity measured by the clinician score method. Three out of four positive patients showed an increased stimulation index in accordance with increased clinician scores during their clinical course. These results could suggest that, in positive patients, a house dust mite allergy might be an active cause that exacerbates clinical symptoms at the time of their clinical course. Therefore, the stimulation index of the lymphocytes stimulation test might become one of the effective parameters that reflect the involvement of a house dust mite allergy in adult atopic patients.

Atopic eczema and allergy

Although the pathomechanisms of respiratory atopy are well established, the role of IgE-mediated hypersensitivity in the elicitation and maintenance of eczematous skin lesions in atopic eczema (AE) is still controversial. There is, however, evidence for exogenous elicitation of AE by contact with aero- or food allergens (house dust mite, cat, and so forth). Recent investigations show that epidermal Langerhans' cells bind IgE via different receptors, especially the high-affinity receptor (Fc epsilon RI), which is significantly more strongly expressed in lesional skin of AE compared with other inflammatory skin diseases including allergic contact dermatitis. The clinical relevance of IgE-mediated sensitization in AE has been evaluated by the so-called atopy patch test (APT). The APT shows a much higher specificity compared with the skin prick test and radioallergosorbent test. However, allergic reactions do not play a decisive role in every case of AE. Other factors, such as nonspecific skin irritability or psychosomatic interactions, have to be considered. The concept of "extrinsic" versus "intrinsic" types of AE seems attractive. The concept of AE starting with TH2 inflammation, becoming TH1 inflammation in chronicity, and finally progressing to an autoimmune disease with IgE antibodies against autologous epidermal proteins is very attractive. Based on new knowledge, new methods in diagnosis, treatment, and prevention will develop, including more effective avoidance strategies, more potent anti-inflammatory treatment (e.g., immunomodulation or topical immunophyllins), and new ultraviolet modalities. The new findings have given rise to a possible new classification of eczema/dermatitis. The concept of "patient management," including all aspects from avoidance to therapy, has gained acceptance.

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.

Immediate and delayed hypersensitivity to mite antigens in atopic dermatitis

Atopic dermatitis (AD) is a common disorder and appears to be on the increase, especially among children. It was thought at first to be a manifestation of immediate hypersensitivity, but it is now known that delayed hypersensitivity also plays an important role. Sensitivity to mite antigens is found in 20% to 60% of patients when immediate hypersensitivity is evaluated by the detection of specific IgE antibodies and prick tests, and in 30% to 50% of patients when delayed hypersensitivity is studied by patch testing. A prospective randomized study was carried out in the pediatric dermatology clinic on a sample of 51 children under 15 years of age. A prevalence of immediate and delayed hypersensitivity to mites, like that described for other populations, was found. It was further found that there was a positive association, not described in the literature, between the younger age groups and delayed hypersensitivity to mite antigens, while the opposite was true for immediate hypersensitivity. We believe that patch tests with airborne allergens, specifically mites, should be part of the protocol for assessing children with AD, particularly in the younger age groups.

Ceramidase activity in bacterial skin flora as a possible cause of ceramide deficiency in atopic dermatitis

A marked decrease in the content of ceramide has been reported in the horny layer of the epidermis in atopic dermatitis (AD). This decrease impairs the permeability barrier of the epidermis, resulting in the characteristic dry and easily antigen-permeable skin of AD, since ceramide serves as the major water-holding molecule in the extracellular space of the horny layer. On the other hand, the skin of such patients is frequently colonized by bacteria, most typically by Staphylococcus aureus, possessing genes such as those for sphingomyelinase, which are related to sphingolipid metabolism. We therefore tried to identify a possible correlation between the ceramide content and the bacterial flora obtained from the skin of 25 patients with AD versus that of 24 healthy subjects, using a thin-layer chromatographic assay of the sphingomyelin-associated enzyme activities secreted from the bacteria. The findings of the assay demonstrated that ceramidase, which breaks ceramide down into sphingosine and fatty acid, was secreted significantly more from the bacterial flora obtained from both the lesional and the nonlesional skin of patients with AD than from the skin of healthy subjects; sphingomyelinase, which breaks sphingomyelin down into ceramide and phosphorylcholine, was secreted from the bacterial flora obtained from all types of skin at similar levels for the patients with AD and the healthy controls. The finding that the skin of patients with AD is colonized by ceramidase-secreting bacteria thus suggests that microorganisms are related to the deficiency of ceramide in the horny layer of the epidermis, which increases the hypersensitivity of skin in AD patients by impairing the permeability barrier.

Clinical, immunological and MRI features of myelitis with atopic dermatitis (atopic myelitis)

In order to clarify the characteristic features of myelitis with atopic dermatitis (AD), we compared the clinical, immunological and MRI findings between 14 myelitic patients with AD and 12 myelitic patients without AD. The myelitic patients with AD showed the following distinct features, compared with those without AD. (1) A preferential involvement of the cervical cord, as shown by neurologic as well as MRI examinations (14/14 vs. 5/12; P=0.0012), (2) paresthesia/dysesthesia as the predominant symptoms and a rare occurrence of definite muscle weakness (0/14 vs. 5/12; P=0.0120) and dysuria (1/14 vs. 8/12; P=0.0029), (3) a lower Expanded Disability Status Scale score (mean, 1.5 vs. 3.5; P=0.0018), (4) normal cerebrospinal fluid (CSF) findings including those for the IgG index and oligoclonal IgG bands and (5) a persistence of neurologic symptoms and MRI lesions during the follow-up periods (mean, 17 months). In addition, both the serum total IgE level and the frequency of specific IgE to Dermatophagoides farinae were significantly higher in the myelitic patients with AD (median IgE=1266 U/ml, specific IgE 14/14) than in those without AD (145 U/ml, P=0.0034 and 8/12, P=0.0331, respectively) and in 40 healthy controls (86 U/ml, P<0.0001 and 12/40, P<0.0001, respectively). Since myelitis with AD has distinct features and atopy to mite antigens appears to be the underlying cause of this condition, it may therefore be a distinct subtype of myelitis.

Purification and characterization of a novel ceramidase from Pseudomonas aeruginosa

We report here a novel type of ceramidase of Pseudomonas aeruginosa AN17 isolated from the skin of a patient with atopic dermatitis. The enzyme was purified 83,400-fold with an overall yield of 21.1% from a culture supernatant of strain AN17. After being stained with a silver staining solution, the purified enzyme showed a single protein band, and its molecular mass was estimated to be 70 kDa on SDS-polyacrylamide gel electrophoresis. The enzyme showed quite wide specificity for various ceramides, i.e. it hydrolyzed ceramides containing C12:0-C18:0 fatty acids and 7-nitrobenz-2-oxa-1, 3-diazole-labeled dodecanoic acid, and not only ceramide containing sphingosine (d18:1) or sphinganine (d18:0) but also phytosphingosine (t18:0) as the long-chain base. However, the enzyme did not hydrolyze galactosylceramide, sulfatide, GM1, or sphingomyelin, and thus was clearly distinguished from a Pseudomonas sphingolipid ceramide N-deacylase (Ito, M., Kurita, T., and Kita, K. (1995) J. Biol. Chem. 270, 24370-24374). This bacterial ceramidase had a pH optimum of 8.0-9.0, an apparent Km of 139 microM, and a Vmax of 5.3 micromol/min/mg using N-palmitoylsphingosine as the substrate. The enzyme appears to require Ca2+ for expression of the activity. Interestingly, the 70-kDa protein catalyzed a reversible reaction in which the N-acyl linkage of ceramide was either cleaved or synthesized. Our study demonstrated that ceramidase is widely distributed from bacteria to mammals.

Disaggregation of corneocytes from surfactant-treated sheets of stratum corneum in hyperkeratosis on psoriasis, ichthyosis vulgaris and atopic dermatitis

To elucidate the pathogenesis of impaired barrier function and the influence of surfactant on the stratum corneum in hyperkeratosis, we investigated morphological alterations of the corneocytes with soap solution. Groups of five patients each with psoriasis vulgaris (PV), ichthyosis vulgaris (IV), atopic dermatitis (AD), and normal controls were examined. Four samples of the horny layer were obtained from the same site by cyanoacrylate adhesive biopsy. The first sample was used for the superficial layer, and the fourth, for the basal horny layers. Each sample was agitated in 1% stirred soap solution at 60 degrees C. The number and size of isolated corneocytes and the morphologic changes were investigated. The release of corneocytes was greater and the swelling and morphological changes of corneocytes exposed to soap solutions were less in PV and AD than in IV or in healthy subjects. In IV, the release was markedly less than in controls. The release and swelling were greater in the superficial than in the basal horny layers. It was concluded that the cohesiveness of corneocytes was probably less in PV and AD and greater in IV than in normals. It was also suggested that the cohesion of corneocytes from the superficial horny layer was less than that from the deep layer. The permeability of the cornified envelope in PV and AD patients was less than in IV or healthy subjects. It was confirmed that highly potent soaps induce loss of many corneocytes and reduce the barrier function of the stratum corneum.

Increased number of IgE positive Langerhans cells in the conjunctiva of patients with atopic dermatitis

AIM

To determine the role of Langerhans cells (LCs) found to bear IgE in patients with atopic dermatitis (AD) by evaluating the surface distribution of these cells in the conjunctival epithelium and epidermis of skin lesions in patients with AD.

METHODS

The double labelling method was used to evaluate IgE positive cells that were positive for anti-CD1a or anti-CD23 antibody in an epithelial sheet of the conjunctival limbus. Specimens of conjunctiva were obtained from 12 men, six of whom had AD and ocular complications. Five patients without atopic disease served as controls, plus one additional patient with asthma but no AD. A similar study was conducted using epidermal sheets obtained from two patients with AD and from one without AD.

RESULTS

The number of CD1a+ cells present in the conjunctival epithelium of the patients with AD significantly exceeded that of the patients without AD. Most CD1a+ cells in the conjunctival epithelium and epidermis from the patients with AD bore IgE on their surfaces. Few such cells from patients without AD bore IgE. No CD23+ cells were found in the patients with or without AD.

CONCLUSIONS

The presence of an increased number of LCs bearing IgE on their surfaces in the conjunctival epithelium of patients with AD suggests that these cells may be involved in eliciting the hypersensitivity reaction and participate in ocular inflammation.

Contact dermatitis

LEARNING OBJECTIVES

Reading this article will reinforce the reader's knowledge of the definition, pathophysiology, differential diagnosis, evaluation, and management of the most common of all the "eczemas," contact dermatitis, which can have an allergic and/or an irritant pathogenesis.

DATA SOURCES

Relevant articles and current texts on contact dermatitis were referenced and reviewed. The personal experiences of the authors in an Environmental Medicine Clinic, their private practices, and their teaching of residents and other physicians were evaluated. A MEDLINE database using subject keywords was searched from 1986 to date.

STUDY SELECTION

Book chapters, pertinent articles, data source abstracts, guidelines for the management of contact dermatitis set by the American Academy of Dermatology, and the American Contact Dermatitis Society were critiqued.

RESULTS

The recent elucidation of the pathoimmunology of contact dermatitis is concisely reviewed, highlighting its clinical implications. The protean clinical presentations of contact dermatitis, both "allergic" and "irritant" type are cited. The signs and symptoms warranting the search for a contactant are outlined. The most likely regional contactants are listed, but the need to reference a more complete textbook is often required. That patch testing is the gold standard to identify an allergenic agent causing allergic contact dermatitis is stressed. While the "who" and "when" to patch test is amply described, a cookbook "how" to patch test has been omitted in order to emphasize the importance of "hands on" experience for such testing. The advantages and limitations of the commercially available standard patch tests (Hermal, and T.R.U.E.) are described, plus the sources for "nonstandard" patch tests is made available. Therapeutic modalities, topical and systemic, for management of the uncomfortable patient are outlined.

CONCLUSION

The physician who manages a patient with an "eczematous" rash must be aware of the complete differential diagnosis of that clinical presentation. Suspicion that a "contactant" is the cause must have high priority, especially when the rash is persistent, and fails to respond to "appropriate" therapy. The value of a skin biopsy is limited to confirming its eczematous (spongiotic) nature and ruling out other diseases. Appreciating the paradox of patch testing, namely the deceptive simplicity of application versus the required expertise for interpretation and recognition of clinical significance, is the key to the proper management of the patient with contact dermatitis.

Presence of elevated carcinoembryonic antigen on absorbent disks applied to nipple area of breast carcinoma patients

BACKGROUND

Carcinoembryonic antigen (CEA) is used as a serum marker to detect and monitor the status of various kinds of malignant tumors. To determine whether CEA might be detected in secretions collected topically from around the nipple area, and whether its secretion might differ in a cancerous versus a noncancerous breast, we developed a simple method for collecting and measuring CEA, using a small cellulose membrane disk and an enzyme immunoassay.

METHODS

We measured the amount of CEA excreted from the nipple area of 22 healthy control women and 32 women with unilateral breast carcinoma confirmed histologically. Secretions were collected from the nipple area by affixing a small (20 mm diameter) absorbent disk made of nitrocellulose membrane backed with filter paper to that area for 24 hours. Substances absorbed by the membrane were then subjected to an immunoassay for CEA using anti-CEA antibodies.

RESULTS

In the 22 healthy subjects, a small amount of CEA (0.6 +/- 0.9 units) was secreted from each nipple, which was equally low regardless of the phase of the menstrual cycle. In contrast, 30 of the 32 women with breast carcinoma secreted significantly greater amounts of CEA from the cancerous (16.1 +/- 8.2) than the noncancerous (2.0 +/- 2.2) breast. Such a difference (14.1 +/- 8.0) in CEA excretion was not observed in the healthy controls (0 +/- 0).

CONCLUSIONS

These findings suggest that such disks may provide a simple and noninvasive method of collecting trace molecules, including CEA, in skin secretions around the nipple to evaluate functional disorders of the mammary glands, particularly breast carcinoma. Additional studies are indicated in larger groups of women with various stages of breast carcinoma as well as with benign breast diseases.

Contact allergy to aeroallergens in children with atopic dermatitis: comparison with allergic contact dermatitis

Immediate and delayed cutaneous hypersensitivity are believed to be implicated in the physiopathology atopic dermatitis (AD). The purpose of this study was to evaluate Type I and Type IV allergy to aeroallergens in children with AD. 59 children (mean age 5.2 years), presenting with AD according to Hanifin and Rajka's criteria, were skin tested (patch and corresponding prick tests) with common environmental aeroallergens and a restricted panel of the European standard series over a 1-year period. History and clinical data were carefully recorded using a standardized evaluation sheet; total and specific IgE serum levels were evaluated. 17 of 59 patients (28.8%) had at least 1 positive patch test, 32 of 59 patients (54.2%) had at least 1 positive prick test. Corresponding patch and prick tests were observed in 8 out of 17 patients. 5 children with positive patch tests had negative prick tests. Irritant pustular reactions (2/59, i.e. 3%), "angry back" reactions (6/59, i.e. 10%) and doubtful reactions (3/59, i.e. 5%) were excluded from the positive group. Positive patch tests observed included, in decreasing order: D. pteronyssinus and D. farinae (26.8%), garden trees (12.2%), plantain (9.8%), timothy grass, mugwort and damp area trees (4.9% each), and orchard grass (2.44%). 6 children with positive aeroallergen patch tests and 11 children with negative aeroallergen patch tests had at least 1 positive patch test to standard allergens. All children with an irritant reaction to aeroallergens had no reaction to standard patch tests. The relevance of aeroallergens in upgrading the severity of AD lesions has still to be explored by challenge studies and by long-term follow-up.

Atopic dermatitis: an update

This review focuses on recent literature regarding the following clinical features of atopic dermatitis (AD); diagnostic criteria, epidemiology and genetics, provocative factors, predictors of disease development and markers of disease severity, therapy, and prognosis. For example, the frequency of AD appears to be increasing, perhaps in response to provocative factors such as food allergens and house dust mites. Determination of reliable markers for disease development may identify susceptible newborns and facilitate avoidance of relevant triggers. Immunomodulating therapy holds promise in the treatment of refractory AD, and new investigation has led to refinements in conventional modalities such as antihistamines and phototherapy.

The spectrum of cutaneous patch-test reactions in patients with atopic dermatitis

We have outlined rationale and problems associated with three types of patch tests that may provide diagnostic help in patients with difficult-to-manage AD. Each of these methods is imperfect and in need of greater study using a critical approach, better techniques, more attention to irritant controls, and better definition of atopic populations. Proof of validity for aeroallergen patch testing will necessarily require large quantities of purified antigens. In spite of all these problems, patch testing can be useful and sometimes essential for the diagnosis and management of difficult AD.

Combined skin prick and patch testing enhances identification of food allergy in infants with atopic dermatitis

BACKGROUND

Early recognition of dietary allergies in infants with atopic dermatitis is essential for avoidance of unnecessary elimination diets, amelioration of the skin disease, and secondary prevention of the development of multiple food allergies. Simple and accurate methods of identifying provocative foods are urgently needed.

METHODS

The usefulness of skin prick and patch tests as indicators of cow milk allergy was evaluated in 183 patients ranging in age from 2 to 36 months with double-blind, placebo-controlled (n = 118) or open (n = 65) cow milk challenges.

RESULTS

The oral cow milk challenges were interpreted as positive in 54% of both challenge types. Positive challenge rapidly elicited pruritus, urticaria, and/or exanthema in 49% of cases and delayed-onset eczematous lesions in 51%. The skin prick and patch tests gave markedly discrepant results; prick tests were positive in 67% of the cases with acute-onset reactions to milk challenge, whereas patch tests tended to be negative. Patch tests were positive in 89% of those with delayed-onset reactions, although prick tests were frequently negative.

CONCLUSIONS

The observations indicate that IgE and T cell-mediated responses to cow milk can be distinguished in atopic dermatitis. Parallel skin testing with combined prick and patch tests can significantly enhance the accuracy in diagnosis of specific dietary allergies in patients with atopic dermatitis.

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 to Dermatophagoides with patch test results, 313 atopic dermatitis (AD) patients and 100 healthy volunteers (HV) underwent patch tests with: Dermatophagoides pteronyssinus (DPT) lyophilized purified alpha fraction in buffered saline/glycerol 50% and/or in petrolatum (Bayropharm); 50% 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. 38% of AD patch-test-positive patients and 4 of 13 HV, respectively, showed a positive prick test and/or RAST to Dermatophagoides. Similar sensitization rates were observed with the allergenic material from Bayropharm (54% positives) and Allergopharma-Bracco (51% positives), whereas the preparations from Lofarma gave a 20% response rate.