Influence of patch-test application tape on reactions to sodium dodecyl sulfate

There remains much room for improvement in the accuracy of the patch test procedure. There has been a lack of knowledge regarding the possible relationship between the intensity of test reactions and the quality of the tape used to apply patch tests. Using different brands of tape, patches coated with 2 mg/cm² sodium dodecyl sulfate (SLS) were applied for 24 h to the backs of 10 volunteers. The tape specimens varied in terms of manufacture, elasticity, adhesive strength, and water permeability. The intensity of patch test reactions, evaluated visually and objectively with both the high resolution laser Doppler perfusion imaging technique (HR-LDPI) and transepidermal water loss measurements (TEWL), varied significantly with the different brands of tape. Observed variations in the intensity of reactions to the patch tests could not be explained by any of the 4 tape parameters investigated. In order to attain optimal test quality in the future, both the tape and patches used in the testing system should be standardized and clearly labelled.     

Effect of test techniques of perfusion of neomycin sulfate patch tests. A comparative study with visual assessments

Effects of test techniques on neomycin patch test results have not been thoroughly investigated. This study focuses on effects of dose and application time of neomycin sulfate patch tests on test results. The effects are assessed both visually and by perfusion. 16 subjects positive to neomycin are retested with neomycin sulfate in various doses and vehicles applied with different application devices for variable time intervals. All subjects were tested with a serial-dose series for time intervals ranging from 3 to 96 h (4 days [D]). The results show very good agreement between perfusion assessments and positive and negative visual assessments of reactions; however, a gray zone was detected where reactions with variable perfusion were associated with visually questionable test responses. 1:27 serial dilutions and wide application time intervals show a positive response with perfusion assessments and partly with visual assessments. Regardless of reading technique, highest reactivity of reactions was detected at either 96 h (day [D] 4) or 168 h (D7) in each subject with minor exceptions, regardless of dose, vehicle, application device or application time. Some findings of the study support the idea that reactions with papules alone are positive tests. Possible effect of tapes and foils on test results are discussed.     

Assessment of budesonide patch tests

Patch-test technique for budesonide needs improvement. 20 subjects with positive or questionable patch-test responses to budesonide were retested for 3 to 96 h (4 days [D]) with polyester patches coated with budesonide in serial doses (150 to 0.074 microg/cm2). Multiple readings were taken visually and with a laser Doppler perfusion imaging technique up to 264 h (day [D]11). Additionally, all subjects were tested with 0.1% budesonide in petrolatum in Finn Chambers for 48 h (2D) with readings taken at 72 (D3), 96 (D4) and 168 h (D7). Different dose levels and application times affected unpredictably highest assessments of reactions. No clear suppression of reactivity was observed at high doses. Time points of highest assessments of reactions varied between subjects but were generally the same for each subject with both reading methods regardless of dose levels or application times. Positive and negative subjects during the study were easily distinguished with all serial doses, regardless of assessment technique. At 2.0 microg/cm2, the lowest dose level tested on all subjects, longer applications than 24 h (1D) were required to detect all positive subjects. 48-h (2-D) applications required 2 readings, optimally at 96 (D4) and 216 h (D9). The only test technique with Finn Chambers used here did not make such distinction possible.     

Effect of dark test-substance pigmentation on skin perfusion assessments and effect of test technique on balsam of Peru patch-test results

13 balsam of Peru (Myroxylon Pereirae) patch-test-positive subjects are re-tested with 25% balsam of Peru in petrolatum and with serial doses printed on polyester squares. All substances are applied with tape strips for 3, 6, 24 (1 day [D]), 48 (2D), 72 (3D) and 96 h (4D) on each subject and for 96 h (4D) with plastic foils. Tests are followed visually and with perfusion assessments from 3 h to 9 days. Results show that pigment remnants following detachment of patches affect perfusion assessments. Such effect due to pigment is supported by readings of patch tests through the petrolatum test substance while applied with transparent foils. For most reactions, good agreement is observed between the assessment techniques when peak assessment values of reactions are compared. There is inter-individual variation in perfusion with identical tests. With the petrolatum test substance, increased visible reactivity was observed when the application time was extended up to 24 h (1D), while extension of application time increased perfusion in most cases except for an extension from 24 (2D) to 48 h (4D) where decreased perfusion resulted in most cases. Dose and application time did not affect the timing of highest reactivity of reactions in most cases.     

P31Patch test reactions in the elderly

Objective:  To investigate whether application of allergic patch tests with transparent semi‐occlusive adhesive plastic foils yields higher test sensitivity than when tapes are used. To study whether such foils compared to tapes allow a shorter application time of tests.
Methods:  We applied different doses of budesonide printed on polyester squares and vehicle control squares to budesonide allergic subjects for 4 days. Each subject was tested with a set of tests both with a tape and a foil. We assessed all tests when they had been detached and additionally those applied with foils at earlier time points. All assessments were performed both visually and with a laser Doppler perfusion imaging technique.
Results:  Test sensitivity is higher with foil applications than when tapes are used and the perfusion is higher with the foils in many cases. The foils allow detachment of visually positive tests before 48 hours in some subjects, regardless of dose.
Conclusions:  Test applications with transparent semi‐occlusive adhesive plastic foils is sensitive and should be considered for application of patch tests when a short application time is important as when tests are carried out with occupationally hazardous allergens or when test substances containing allergens are expected to be irritating.     

Objective non-invasive assessment of patch tests with the laser Doppler perfusion scanning technique

The laser Doppler perfusion scanning technique is an objective, non-invasive assessment method that may be used to assess patch tests. The purpose of this paper is to focus on its clinical use in individuals with light skin, tested with non-pigmented test materials. A laser Doppler perfusion imager PIM 1.0 (LDPI) is used to study different set-ups of the instrument that may affect readings. These set-ups are studied through simulated light-absorbing patch tests. The results have served as a base for clinical experiments comparing visual and LDPI assessments of normal skin, irritant patch-test reactions, and more than 25,000 allergic patch-test assessments of reactions of different intensities and control patches. This paper reviews the clinical experiments to suggest a set-up of the LDPI for patch-test readings. Such a set-up makes it possible to compare intra- and inter-individual test results and to obtain meaningful assessment values among users. Some subject-related factors that may affect reading results are studied, and the effect of non-subject related factors on readings are considered. Use of the technique is illustrated by images of perfusion and a perfusion profile of a patch-test reaction followed over time.     

Visual scoring and laser Doppler perfusion imaging of skin irritancy induced by different nicotine patches

Background/aims: Local skin reactions are the most common reason for discontinuation of transdermal nicotine replacement therapy in smoking cessation programs. The aims of the present study were (1) to quantify the intensity of skin reactions induced by different types of nicotine patches and (2) to compare the clinical evaluation of skin erythema using visual scores with independently performed quantitative estimates of skin perfusion.
Methods: Thirty-three subjects were included in the study, each receiving 2 different types of nicotine patches (Nicotinell and Nicorette) and 1 type of placebo patch (Nicorette), placed ventrally on the upper arms according to a randomized protocol. Patches were removed after 24 h (Nicotinell) and 16 h (Nicorette), respectively, according to recommended application times. Visual scoring and laser Doppler perfusion imaging were performed 45 min after removal of patches, in a randomized order.
Results: Nicotinell patches induced the highest cumulative clinical score for skin irritancy. All 3 investigated patches gave rise to a slight but significant skin perfusion increase and individual visual scores and perfusion data correlated.
Conclusion The degree of skin irritancy and underlying perfusion increase induced by 1 daily maintenance dose of transdermal nicotine via a patch is low, but differs between patch types.     

Assessment of balsam of Peru patch tests

To find an ideal test technique for as low a dose of balsam of Peru (Myroxylon Pereirae) as possible, subjects testing positive to balsam of Peru are re-tested with a 25% concentration of balsam of Peru in petrolatum. Applications are with Finn Chambers for 6 different application times, and directly by foils for 96 h (4 days (D)). The goals are to confirm which subjects are positive and which are not, and, using that information, to see if it is possible to distinguish between these 2 groups, tested concomitantly at much lower serial dose levels, in terms of perfusion or by visual assessments. 5 different serial doses are applied with strips for 3-96 h (4D) and with foils for 96 h (4D). The Finn Chamber tests allow a distinction between visually positive and negative subjects supported by perfusion assessments. With the foils, a 24x lower serial dose level than with the 25% test substance is sufficient to distinguish between positive and negative subjects in terms of perfusion values. This approach requires readings up to 9 days. With this test, the visual approach yields only 3 of 10 positive subjects. This study demonstrates that a lower test dose is possible with perfusion assessments compared to visual ones.     

Correlation between laser Doppler perfusion imaging and visual scoring of patch test sites in subjects with experimentally induced allergic and irritant contact reactions

Purpose: To compare laser Doppler perfusion imaging (LDPI) measurements in experimentally induced allergic contact reactions and irritant contact reactions. The degree of correlation between visual scores and LDPI measurements was also studied.
Methods: Fifteen patients with known contact allergy to nickel or fragrance were patch tested with nickel sulfate 5% pet., fragrance mix 8% pet., sodium lauryl sulfate (SLS) 0.5% pet., SLS 1.0% pet. and two empty control chambers. Visual readings and LDPI measurements were taken at 0, 48 and 96 h.
Results: There was a positive correlation between visual scores and LDPI measurement in the nickel sulfate and fragrance mix patch test sites. However, no correlation between visual scores and LDPI measurements was seen in the SLS 0.5% and SLS 1.0% patch test sites. There was no significant difference ( P =0.125) in LDPI measurements between contact-allergic reactions and contact-irritant reactions.
Conclusion: LDPI correlates with visual scoring in contact-allergic reactions, but not in irritant reactions. LDPI is not useful in distinguishing between allergic and irritant reactions.     

Patch testing with neomycin sulfate

The recommended patch test concentration of neomycin sulfate is 20% in petrolatum applied occluded for 48 h (2 days [D]). In the current study, the efficiency of such a test is compared to results with other techniques using lower allergen dose than obtained by approximately 20 microl of the 20% substance. Efficiency of petrolatum and demineralized water as vehicles are compared. 16 neomycin-sulfate positive subjects were retested with serial doses ranging from 0.4 to 0.0085 mg/cm2 neomycin sulfate in cellulose printed on polyester squares and applied by both tapes and plastic foils. Additionally, tests were performed with the 20% petrolatum substance in Finn Chambers. Tests containing the 20% substance in petrolatum and in water were applied directly with transparent foils. Readings ranged from 3 to 264 h (11D) following applications. Results show that foil applications of a polyester square dose, that is 7% of the dose obtained with the 20% substance, distinguished between perfusion of subjects who were visually positive and not with any test in the study. With the same test technique and visual assessments, 2 subjects were false-negative but developed doubtful test responses with the Finn Chambers.     

Nickel: the search for alternative, optimal and non-irritant patch test preparations

Background/aims: Several contact allergens including nickel are also irritants. Ideal patch test preparations should not miss cases of contact allergy and should be non-irritant. The currently used nickel preparation (5% nickel sulfate in petrolatum; 0.19 m) is a compromise. The present aim was to compare the skin-irritant potential of various nickel preparations (sulfate, chloride, nitrate in petrolatum and in water) by using the objective, noninvasive laser Doppler technique for assessment.
Methods: Preparations with various nickel concentrations and vehicle controls were applied under occlusion (Finn chambers) on the volar forearms of healthy subjects for 48 h. The test sites were examined visually and measured with a laser Doppler flowmeter before, and repeatedly after, removal of test patches. Some preparations were also used when patch testing consecutive dermatitis patients.
Results: 0.19 m nickel chloride and nickel nitrate in petrolatum caused erythema as well as increase in skin blood flow, while lower concentrations (0.10, 0.05 and 0.01 m) did not affect skin blood flow. At higher concentrations the sulfate was less reactive than the other salts. The reactivity was more pronounced with the salts in petrolatum than in water. 0.05 m nickel nitrate was equivalent to 0.19 m nickel sulfate in diagnosing contact allergy in patch testing, while 0.30 m nickel sulfate in water missed several cases.
Conclusions: The laser Doppler technique is more sensitive than the naked eye and can indicate nickel patch test preparations with marginal irritant properties. Some promising alternative candidates have been identified.     

Skin irritation typing and grading based on laser Doppler perfusion imaging

Background/aims: Vasodilation with increased cutaneous perfusion is an essential part of an irritant inflammatory response. The aim of the present study was to investigate the usefulness of the high-resolution laser Doppler perfusion imaging (HR-LDPI) technique for investigating irritant skin reactions. Irritants may elicit clinically different reactions due to different skin penetration profiles and different modes of irritant action on the exposed tissue.
Methods: Twelve subjects were tested on the forearms using 24 h occlusive application of three concentrations of the irritants sodium lauryl sulphate (SLS) and nonanoic acid (NON) and with the topical acne drug all-trans retinoic acid (RA). Cutaneous blood flow at baseline, the increase in cutaneous blood flow and the skin area having increased perfusion were measured on day 2, day 3 and day 5.
Results: Based both on measurement of mean perfusion and area with increased perfusion, it was possible to differentiate between different clinical irritation grades on any study day. The area with increased perfusion exceeded the area with clinically visible skin reactions for irritant reactions of grade ¹/₂ and above. Irritant reactions for individual irritants could furthermore be typed using HR-LDPI. It was possible to differentiate between vehicle treatment and the different dose levels of the irritant compounds. A correlation was found between clinical scores for the individual irritants and the mean flow and the area with increased flow. The individual irritants could be differentiated due to different time courses of their skin irritation.
Conclusion: Laser Doppler imaging was found to be an important new method for characterization and grading of the inflammatory response of single exposure irritant reactions. However, standardised study procedures cannot be emphasised enough in order to obtain reliable and useful data.     

Two-dimensional blood flow determinations in allergic reactions using laser Doppler scanning

The new technique of laser Doppler scanning (LDS) provides a 2-dimensional pattern of cutaneous microcirculation, which offers a visual image and can quantify the intensity and expansion of perfusion. With the help of this technique, we examined the microcirculatory pattern of Type IV reactions to recall antigens, which were applied using a test stamp (Multitest Merieux). The measurements were performed before application of the test stamp as well as 10 min, 24, 48 and 72 h afterwards. The inflammatory hyperemia was evaluated using LDS and unidimensional laser Doppler fluxmetry. The diameter of the inflammatory infiltrate was quantified by means of palpation, the thickness by means of high-resolution 2U MHz sonography. The clinically visible erythema was measured planimetrically. An unspecific hyperemia resulting from the trauma of the stamp revealed no evident infiltrate under sonography 10 min after the test application. Depending of the individual reaction, the mean flux and the expansion of the hyperemia were at their peak after 48 h. The flux values were at a maximum in the center of the inflammatory reaction and dropped continuously toward the periphery. The area of the hyperemia seen in the LDS image was significantly larger than the expansion of the erythema measured planimetrically, but there was a significant correlation. The perfusion correlated significantly with the infiltration diameter (24 h, 48 h, 72 h) and the infiltration thickness 48 h after testing. All in all, it was possible to measure directly and without touching the skin and to quantify a subclinical pattern of skin perfusion as a response to and inflammatory reaction on a 2-dimensional display.     

Quantification of patch test reactions by transcutaneous PO2 measurement

The usefulness of transcutaneous oxygen tension (tc-PO2) measurement for quantification of positive patch test reactions was studied. A significant correlation was found between the visual grading and the quantitative tc-PO2 values. Tc-PO2 discriminated between visual grade 0 to 1+, 1+ to 2+, and 2+ to 3+ reactions. The results obtained by this method were compared with those obtained by other quantitative methods. Tc-PO2 measurement can be regarded as complementary to the laser Doppler technique, since it lacks the sensitivity of the laser Doppler technique in the range in negative to 1+ patch reactions, but it does discriminate between 2+ and stronger reactions.     

Evaluation of an experimental patch test model for the detection of irritant skin reactions to moisturisers

Background/aims: Moisturisers are used daily by a large number of people to prevent dryness of the skin. Irritant skin reactions to moisturisers are, however, known to occur. In order to prevent such irritant reactions reliable test methods for irritancy testing of moisturisers are needed. This study was undertaken to evaluate a non‐invasive patch test model for the detection of irritant skin reactions to moisturisers. Methods: Twenty healthy volunteers were patch tested with three different moisturisers: empty chamber, sodium lauryl sulphate and a moisturizer known to be non‐irritating. Skin reactions were evaluated by visual scoring, measurement of transepidermal water loss (TEWL) by an Evaporimeter, blood flow by laser Doppler flowmetry and electrical capacitance by a Corneometer. Results: A statistically significant increase in blood flow was found 48 h after application of one of the moisturisers tested, indicating an irritant effect of the product. A statistically significant decrease in skin hydration was found for the same moisturiser after 48 h. No statistically significant differences between the moisturisers were found by visual scoring. None of the products tested had any negative effect on the skin barrier function. Conclusion: The non‐invasive patch test model was found useful for detecting irritant skin reactions to moisturisers.     

Analysis of laser Doppler perfusion images of experimental irritant skin reactions

Background/aims: Laser Doppler perfusion imaging (LDPI) permits measurement of skin blood flow changes in patch test reactions. It is, as yet, unclear how collected data can best be handled and presented in order to maximize the possible discriminatory advantage of the imaging technique and to make the selection of data for statistical analysis as objective as possible. The aim of the present study was to compare a new software program (LDISOFT) for the analysis of LDPI images with the built-in standard statistical functions in the LDPI system (PIM 1.0). In addition, a modification of the software was used to gather additional data by performing sequential perfusion images. Methods: A dithranol cream was applied under Finn chambers for 30, 60 and 90 min on the ventral forearm skin of three volunteers. Photographic documentation and LDPI recordings were performed immediately after the removal of the Finn chambers and at 24, 48, 72 and 96 h. By the use of the above mentioned software, rectangular and threshold selected regions of interest were used to find an optimal way of calculating the mean perfusion and extent of the reactions. Results: An LDISOFT threshold of 2 V was adequate and showed agreement (r<0.902, n=78) between mean perfusion analysis performed by LDISOFT (threshold-steered region of interest) and LDPI statistics (rectangular region of interest). The LDISOFT program had the added advantage of comparing application-site size with reaction size. Sequential recordings showed both spatial and temporal perfusion variability. Conclusions: Utilization of the full potential of LDPI will involve optimization of data analysis and presentation. A more “automated” system for data analysis will reduce bias due to subjective selection of analysis area. Particularly in weaker reactions, in irregular shaped or ring reactions and when there is non-specific background irritation, this may represent an advantage. Averaging of sequential recordings reduced background noise.     

Sodium lauryl sulfate irritant patch tests: Degree of inflammation at various times

Irritant reactions were induced on the forearms of 10 normal subjects with 10% aqueous sodium lauryl sulfate under patch test occlusion for 24 h. Test sites were observed at 24, 26, 28, 30, 48, 72 and 96 h and the degree of inflammation recorded. Inflammation was most prominent at 28 h and decreased in intensity over the time course of the study. Inflammation at 48 and 72 h was similar to when patches were removed. This suggests that inflammatory responses in skin for at least certain irritants like sodium lauryl sulfate do slowly decrease in intensity after 48 h. However, the inflammatory response may initially accelerate after patch test removal and remain intense for at least 48 h. Fading of irritant reactions by 48 or 72 h may not reliably distinguish irritant from allergic patch test reactions. This does not refute the usefulness of a delayed (96 h) reading since inflammation from sodium lauryl sulfate had decreased significantly by this time.     

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.     

Corneometiy measurements to evaluate skin dryness in the modified soap chamber test*

Background/aims: Patch test procedures have been developed to compare the irritation potential of surfactant-based products. Skin changes due to product application are usually assessed visually by a trained evaluator using standard scoring scales or instrumentally. This study has been carried out to optimize the assessment of skin dryness in the Modified Soap Chamber Test both by visual scoring and Comeometer measurement, with transepidermal water loss as an additional measure. Methods: Products were applied, under occlusion, to the skin, for 2 successive periods of 24 and 21 h; skin reactions were evaluated 3 h after removal of each series of patches, and followed up to 7 days after patches had been removed. Results: Skin dryness progressively develops after patch removal, and reaches a maximum 3 to 5 days later. Capacitance measurements correlate the best with visual scoring of dryness when waiting 5 days after patch removal before assessment. Conclusions: Comeometer is an useful instrument to quantify observed dryness only when transepidermal water loss has recovered a value close to its baseline value. For both visual and instrumental assessments of skin dryness, waiting 3 to 5 days after patch removal in the Modified Soap Chamber Test will provide the most valuable results.     

Evaluation of contact allergy to chemicals using laser Doppler flowmetry (LDF) technique

Skin blood flow in allergic contact reactions and cross-sensitivity were evaluated using laser Doppler flowmetry (LDF) to study the dose-response relationships in phases of induction and challenge in guinea pigs. Guinea pigs were sensitized with different doses of 1-chloro-2,4-dinitrobenzene (DNCB) and challenged with different doses of DNCB and 2,4-dinitrobenzene sulfonic sodium salt (DNBS). The skin reactions were evaluated by LDF and visual reading score. The results indicated that there were dose-response relationships between the doses of DNCB and LDF measurements in both phases of induction and challenge, that there was a cross-reaction between DNCB and DNBS, and that the reactions at 24 h were greater than that at 48 h after removal of the patches. LDF may discriminate between positive patch test reactions and negative or doubtful reactions, but not between weak positive and strong positive reactions. This is because vascular dilatation and increase of flow already reaches a maximum in weak reactions. The more advanced phases are dominated by oedema formation. This is simply the nature of the inflammatory reaction, rather than a methodological error. The important point is that LDF can separate positive reactions from negative/uncertain reactions. The results indicated that LDF, as a non-invasive technique, may objectively and quantitatively evaluate the dose-response relationships of contact sensitivity of sensitizers.