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The influence of patch test size and design on the distribution of erythema induced by sodium lauryl sulfate.

Patch testing is an invaluable tool for the experimental induction of acute irritant contact dermatitis (ICD), with a variety of chamber systems available for use. Ideally, the inflammatory reactions produced should be of uniform intensity across the test area, thereby facilitating grading of the response and tissue sampling for histopathological studies. Unfortunately, annular, follicular and/or blotchy erythema frequently occur. In this study, we set out to compare the performance of 5 patch test systems (8 mm, 12 mm and 18 mm Finn Chambers; 19 mm and 25 mm Hilltop chambers) when testing normal healthy volunteers with sodium lauryl sulfate at concentrations selected to produce mild, moderate and moderately severe reactions. Visual assessment of the patch test sites revealed good dose responses with all 5 chamber types. Uniformity of erythema across the test site was more closely linked to the actual intensity of response than the delivery system itself, mild reactions being far less likely to display homogeneous erythema than moderately severe reactions. Extra large chambers did not perform significantly better than smaller chambers. Balancing the need for a uniform reaction pattern and adequate tissue sampling area, against the exposure risk, we conclude that 12 mm Finn Chambers represent the optimum patch test system for acute SLS-induced irritation where histopathological investigations are the ultimate aim.

Adult↗

Patch test reactions to human dander in atopic dermatitis.

Patch tests reactions to human dander were positive in 120 of 181 (66%) patients with atopic dermatitis, in two of 28 (7%) patients with allergic contact dermatitis, and in one of 31 (3%) normal controls. The frequency of positive reactions was significantly higher in patients with atopic dermatitis. The reactions consisted of erythema and papules, which histologically showed an eczematous change at the upper parts of hair follicles. There was significant correlation between patch test reactions to human dander and delayed intradermal reactions to the same substance in atopic patients. It is suggested that certain patients with atopic dermatitis exhibit contact hypersensitivity to human dander. Whether or not the hypersensitivity has any relationship to the pathogenesis of the dermatitis was not determined in this study.

Adolescent↗

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.

Adolescent↗

Positive patch tests to whole mite culture and purified mite extracts in patients with atopic dermatitis, asthma, and rhinitis.

Patch tests with Dermatophagoides were carried out by different authors on patients with atopic dermatitis (AD) employing methods varying both in the type of allergen and in the way of performing the test. In order to examine and compare different methods and various allergenic materials and to define better the indications for this test, we performed patch tests with whole mite culture or purified mite extracts on 72 patients with AD, 40 subjects with mucosal atopy, and 32 healthy volunteers, employing different techniques of application. Positive results were obtained in 51.5% of patients with AD with specific IgE to Dermatophagoides, in 43.6% of patients with AD without this specific IgE and in 40% of subjects affected by mucosal atopy and having specific IgE to Dermatophagoides. From a technical point of view the simple application of the allergenic material on healthy skin gave the best results. Our data show that patch tests with Dermatophagoides extracts could contribute to a better immunoallergologic characterization both of patients with AD and patients with mucosal atopy.

Adolescent↗

Contact dermatitis with negative patch tests: the additive effect of allergens in combination.

We deduced on theoretical grounds that conventional patch testing would be inadequate for the detection of sensitivity to multiple allergens. Fourteen patients with positive patch tests to two unrelated allergens were studied and the response to those two allergens was measured when tested singly or in combination, using 10 different pair combinations from 15 common allergens. With serial dilutions in chloroform (14 patients) and paraffin (four patients), the response was related to the log-dose of the allergen, and change in skin-fold thickness corresponded well with clinical grading. Single allergens diluted below the threshold for a patch-test response gave a response when given in combination, the threshold for a response to one allergen being lowered by the presence of another. On the linear part of the dose-response curves the response to the mixture of allergens was additive, the combined response being the sum of the individual components. Approaching the plateau region the response to the combination was greater than to the individual allergens but less than the sum of the single responses. The same results were obtained with allergens in paraffin. We conclude that conventional single allergen patch testing by itself is inadequate for the diagnosis of contact dermatitis.

Allergens↗

Isoeugenol: a survey of consumer patch-test sensitization.

The potential of isoeugenol, an important fragrance and flavour ingredient, to induce delayed contact hypersensitivity or to elicit pre-existing sensitization reactions in man was evaluated by analysing patch-test data from dermatitic and non-dermatitic subjects. Results from a total of 6512 patch tests (involving approximately 5850 subjects) on isoeugenol alone and on various consumer products and fragrance blends containing isoeugenol, were collected from fragrance and formulator companies. Hypersensitivity induced by isoeugenol was concentration dependent. All but two of the reactions occurring in this survey were at exposure concentrations greater than or equal to 0.8% isoeugenol. No induced reactions occurred in the 1004 patch tests reported at isoeugenol concentrations between 0.03 and 0.5%. One induced reaction in 32 patch tests was attributable to isoeugenol at a concentration of 0.02% while another induced reaction in 23 patch tests conducted at the same concentration was resolved to an isoeugenol-eugenol mixture. One elicited reaction at an isoeugenol concentration of 0.04% occurred in the 6512 patch tests reported in this survey. This single elicitation was resolved to an isoeugenol-eugenol mixture, but the specific causative agent was not identified. The results of this survey indicate that isoeugenol has a very low potential for either eliciting pre-existing sensitization reactions ('elicited' reactions) or inducing hypersensitivity ('induced' reactions) in subjects exposed to consumer products containing this ingredient.

Dermatitis, Contact↗

Contact leukoderma caused by patch testing with dental acrylics.

Several chemicals are capable of inducing contact leukoderma. Here we report on a dental nurse who had been investigated elsewhere at a dermatology clinic 2.8 years earlier because of suspected occupational fingertip dermatitis. She had been patch tested on her upper arm with dental acrylic resins "as is." These strong concentrations of patch test substances caused a severe allergic reaction in the upper arm, and the patch test sites have remained vitiliginous for 2.8 years. Active sensitization did not take place because the patient had been sensitized earlier as shown by the allergic 2-day readings with acrylics during the first patch test session. It is assumed that acrylates induced contact vitiligo, but the dental acrylics may have also contained other chemicals (eg, hydroquinone or phenolic substances) capable of causing vitiligo. The main point to be learned from the present results is that dental acrylics should never be patch tested "as is." We also discourage the practice of use tests, open tests, or repeated open patch tests with undiluted dental acrylics because of the risk of active sensitization from single exposure.

Acrylic Resins↗

Thermographic assessment of patch-test responses.

Infra-red thermography was used to quantify, at patch test sites, the allergic responses to experimental preparations of nickel sulphate and primary irritant responses to sodium lauryl sulphate in small groups of volunteers. The technique was also used to assess the patch-test responses in a much larger group of patients who had undergone routine patch testing for contact allergy with a wide range of test substances and among which there were large numbers of allergic, irritant and equivocal reactions. Thermographically, when compared to the surrounding normal skin surface, the sites of allergic reactions appeared as hot areas, the temperature and area of which were apparently dependent on the severity of the response. For allergic responses, there was a good correlation between the clinical assessment and either of two thermographic parameters, temperature and area of involvement. Compared with an aqueous solution of nickel sulphate, 'poor' formulations of the allergen, such as a suspension in soft paraffin base, elicited smaller and cooler reactions. Irritant reaction sites were not 'hot' and the temperature at such sites was no different from that of the surrounding normal skin. Infra-red thermography is a convenient non-invasive technique which apparently can be used to discriminate between irritant and allergic responses and to quantify the latter type of response.

Adult↗

Positive atopy patch test reactions to Pityrosporum orbiculare in atopic dermatitis patients.

BACKGROUND: Pityrosporum orbiculare, although a part of our normal cutaneous microflora, can cause skin infections and induce specific immunoglobulin (Ig) E antibodies in atopic dermatitis patients. P. orbiculare is therefore considered to be one of the trigger factors for atopic dermatitis. OBJECTIVE: To investigate if P. orbiculare can induce an eczematous reaction in atopic dermatitis patients, seborrhoeic dermatitis patients and healthy controls. METHODS: Fifteen atopic dermatitis patients, eight seborrhoeic dermatitis patients and eight healthy controls were patch tested with extract of P. orbiculare on non-lesional, tape-stripped skin of the back. NaCl was used as a negative control. The patch tests were evaluated after 24, 48 and 72 h. Skin biopsies were taken from P. orbiculare patch test sites at 24 h and 72 h, from NaCl patch test sites at 72 h, from non-lesional skin and, in the atopic dermatitis patients, also from lesional skin. The skin biopsies were investigated with immunohistochemical techniques. P. orbiculare-specific IgE in serum was analysed with RAST. RESULTS: Specific IgE to P. orbiculare was found in serum from 13/15 atopic dermatitis patients and in eight of them a positive patch test reaction to P. orbiculare was observed, with a maximal reaction at 48 h. Significantly higher serum levels of P. orbiculare-specific IgE were detected in patch test-positive compared with patch test-negative atopic dermatitis patients (P < 0. 01). The seborrhoeic dermatitis patients and healthy controls were RAST and patch test-negative for P. orbiculare. In the patch test-positive atopic dermatitis patients an infiltration of CD4+ T cells and eosinophils was observed at the P. orbiculare patch test sites together with an upregulation of ICAM-1 and HLA-DR expression. CONCLUSIONS: P. orbiculare can induce an eczematous reaction in sensitized atopic dermatitis patients and may be an important trigger factor in these patients. The P. orbiculare patch test can be of diagnostic value in this subgroup of atopic dermatitis patients.

Adolescent↗

Patch tests with some spices.

Experience is necessary to use commercially available spices and seasonings for patch testing. This experience is easily obtained by composing your own series of locally important flavorings and by using this series to assess the irritant potency. In our patients, not many strong irritation reactions were elicited. Only 100 per cent garlic powder was obviously too irritant, whereas 25 per cent in petrolatum might be too low to detect allergy. Positive reactions to unknown spices need to be checked in controls; this is important when patch tests are done with spices brought in by the patient. A positive patch-test reaction to a fragrance or perfume indicator in housewives, cooks, and confectioners with hand eczema is an indication to perform patch tests with spices because of the relation between spices and fragrances.

Condiments↗

Isopropyl myristate recommended for aimed rather than routine patch testing.

Isopropyl myristate (IPM) is considered a very weak sensitizer. Patch test results with 20% IPM in petrolatum (pet.) in 8117 patients and 10% IPM in pet. in 4554 patients between January 1992 and December 2001 by the IVDK are presented. While irritant and questionable reactions were frequently observed, especially with 20% test concentration and 2-day patch test exposure, respectively, and a decrescendo pattern was common, morphologically positive reactions at day 3 were seen in only 16 patients, i.e. altogether 0.13%. In line with previous clinical and experimental evidence, our results indicate that IPM is an extremely weak sensitizer or possibly, in our material, not a sensitizer at all. IPM should thus not be tested routinely, but only in the case of suspected exposure as a possible source of allergic contact dermatitis, e.g. to cosmetics and perfumes, to avoid an unacceptable reduction of the positive predictive value of the test.

Adult↗

Usefulness of the European standard series for patch testing in children. A 3-year single-centre study of 337 patients.

Results of patch tests in 337 children aged 1 to 15 performed in our paediatric unit during the past 3 years have been analysed retrospectively in order to optimize the patch test series and to assess their relevance. This study represents the most important single-centre study reported so far over a short period. We found a positive patch test rate of 66%, with a peak incidence among children less than 3 years of age (88% versus 58.9%). The most common allergens were metals, especially nickel, fragrances and, less frequently, rubber chemicals. Concerning nickel, positive reactions rarely correlated with a relevant exposure and were difficult to interpret, especially in patients with atopic dermatitis, who are probably more likely to have irritant or false-positive reactions to metals. Based on the results and their relevance, we propose a shortened standard series of patch tests for paediatric patients.

Adolescent↗

Keratinocyte expression of class II MHC antigens in long-lasting allergic patch test reactions.

The keratinocyte expression of class II MHC antigens HLA-DR, DP and DQ was studied in 20 long-lasting allergic patch test reactions and 17 normal allergic patch tests reactions. No significant difference in the expression of these antigens in the 2 groups was detected. No 1 allergen was responsible for the majority of long-lasting allergic patch test reactions. The immunological mechanisms which may contribute to long-lasting allergic patch test reactions are discussed with reference to HLA-DR keratinocytes.

Adult↗

Cow's milk allergy: diagnostic accuracy of skin prick and patch tests and specific IgE.

BACKGROUND: The objective of the present study was to evaluate the relevance of skin tests and the concentration of cow's milk-specific IgE antibodies in correlation with oral cow's milk challenge in infants with suspected cow's milk allergy. METHODS: The study material comprised 143 infants under the age of 2 years who had undergone a diagnostic elimination challenge because of suspected cow's milk allergy in 1996. Cow's milk-specific IgE was measured, and skin prick and patch tests were performed. RESULTS: Of the 143 oral cow's milk challenges performed, 72 (50%) were positive. Of the positive reactions, 22 involved immediate-type reactions. In 50 patients, delayed-onset reactions of eczematous or gastrointestinal type appeared. Of the infants with challenge-proven cow's milk allergy, 26% showed elevated IgE concentrations to cow's milk, 14% had a positive skin prick test, and 44% had a positive patch test for cow's milk. Interestingly, in most patch test-positive patients, the prick test for cow's milk was negative. CONCLUSIONS: Our study demonstrated that many patients with a negative prick test result had a positive patch test to cow's milk. The patch test was a more sensitive method than the prick test or RAST to detect cow's milk allergy in this study population. Our results indicate that patch testing will significantly increase the probability of early detection of cow's milk allergy. Confirmation of the diagnosis is essential in patients with negative test results but a clinical suspicion of food allergy, and in patch test-positive patients. For this purpose, the most reliable method is the elimination-challenge procedure.

Allergens↗

Epicutaneous patch testing: current trends and controversial topics.

In the 20th century, epicutaneous patch testing has played an integral and central role in the assessment of allergic contact dermatitis and therefore in general dermatologic practice. After recent verification of the safety and accuracy of patch testing by the Food and Drug Administration, domestic distribution of testing materials has resumed for the first time in 5 years. Because of the importance of this procedure, it is timely to review current standards of epicutaneous patch testing with emphasis on proper use and interpretation, clinical applications, trends in allergic contact dermatitis, and selected controversial issues.

Adult↗

The histological and immunohistochemical pattern of positive patch test reactions to gold sodium thiosulfate.

Gold sodium thiosulfate, inserted in the patch test standard series, gives a surprisingly high yield of positive reactions, about 10% of tested eczema patients, but with a low degree of clinical relevance. A histopathological study on patch test reactions was carried out in patients selected because of a combined contact allergy to gold sodium thiosulfate and nickel. Biopsies were taken from macroscopically similar reactions in dilution series of each allergen. The histological picture was clearly eczematous, without irritative features. In a blind comparison, test reactions induced by the two allergens could not be differentiated from each other. Long-lasting patch test reactions to gold sodium thiosulfate were characterized by an intense lymphocytic dermal infiltrate without epidermal involvement. Immunohistochemically, CD4+ and CD8+ T lymphocytes could be detected already 4-8 h post-challenge, and "naive" as well as "memory"-type T cells were demonstrated. Apparently, our findings reflect a true contact allergy to gold sodium thiosulfate.

Adult↗

Reactivity at edges of corticosteroid patch tests may be an indicator of a strong positive test response.

BACKGROUND: The importance of the reactivity at the edges of corticosteroid patch tests is unknown. OBJECTIVE: To study the clinical importance of edge reactivity in budesonide patch tests. METHODS: Ten subjects previously positive for budesonide patch tests were retested with 0.1% budesonide in Finn Chambers((R)) and with budesonide-printed polyester squares in serial doses (150-0.074 microg/cm(2)). Six exposure periods were used for each polyester square dose (3 h to 4 days). Tests were followed up to 11 days. Doubtful or weakly visible reactivity at the test edges was assessed additionally by test perfusion assessments. RESULTS: Nine of 10 subjects reacted with some edge reactivity and later exhibited positive reactions. Perfusion assessments helped to confirm early edge reactivity. Some allergic subjects showed edge reactivity only at high doses, while longer applications were required for weaker doses. CONCLUSION: Edge reactivity may be an indicator of a strong suppressed test response.

Administration, Topical↗

Oral prednisone suppresses allergic but not irritant patch test reactions in individuals hypersensitive to nickel.

A multicentre, randomized, double-blind, crossover study was designed to investigate the effects of prednisone on allergic and irritant patch test reactions. 24 subjects with known allergy to nickel were recruited and patch tested with a nickel sulfate dilution series in aqueous solution, 5% nickel sulfate in petrolatum and 2 dilution series of the irritants nonanoic acid and sodium lauryl sulfate. The subjects were tested x2, both during treatment with prednisone 20 mg oral daily and during placebo treatment. The total number of positive nickel patch test reactions decreased significantly in patients during prednisone treatment. The threshold concentration to elicit a patch test reaction increased and the overall degree of reactivity to nickel sulfate shifted towards weaker reactions. The effect of prednisone treatment on the response to irritants was divergent with both increased and decreased numbers of reactions, although there were no statistically significant differences compared with placebo. It is concluded that oral treatment with prednisone suppresses patch test reactivity to nickel, but not to the irritants tested.

Administration, Oral↗