Variation in the amount of petrolatum preparation applied at patch testing

Results of patch testing with five fragrance materials hitherto not tested: A dose-finding study in the clinical population

BACKGROUND

Quantitative risk assessment (QRA) for skin sensitization is used to derive safe use levels of sensitising fragrance ingredients in products. Post-marketing surveillance of the prevalence of contact allergy to these ingredients provides relevant data to help evaluate the performance of these measures.

OBJECTIVES

To determine a suitable patch test concentration for five fragrance materials that had hitherto not been tested on a regular basis. These concentrations are then to be used in a surveillance study with patch testing consecutive patients over an extended monitoring period.

MATERIALS AND METHODS

Furaneol, CAS.3658-77-3; trans-2-hexenal, CAS.6728-26-3; 4,8-dimethyl-4,9-decadienal, CAS.71077-31-1; longifolene, CAS.475-20-7; benzaldehyde, CAS.10052-7, were patch tested with other fragrance allergens in four clinics. Patch testing was conducted in three rounds, starting with the lowest concentrations of the five ingredients. The doses were increased in the subsequent rounds if no late-appearing positive reactions and virtually no irritant reactions were reported.

RESULTS

Overall, 373 patients were tested. No positive allergic reaction was reported to the five ingredients. Patch test results of other fragrance allergens are reported.

CONCLUSIONS

The highest test concentrations are each considered safe for patch testing consecutive patients. Further surveillance based on these preparations will evaluate the hypothesis that QRA-driven consumer product levels of these fragrances can prevent sensitization.

Patch Testing With Nickel Sulfate 5.0% Traces Significantly More Contact Allergy Than 2.5%: A Prospective Study Within the International Contact Dermatitis Research Group

BACKGROUND

Nickel allergy is the most common contact allergy, and a nickel salt is, therefore, included in most baseline patch test series. In the baseline series of the International Contact Dermatitis Research Group and the American Contact Dermatitis Society, nickel sulfate hexahydrate (NSH) in petrolatum at 2.5% is included, whereas NSH at 5.0% is included in many other baseline series, such as the European and Swedish ones.

OBJECTIVE

The aim of the study is to investigate whether NSH at 5.0% detects significantly more contact allergy than NSH 2.5% when both preparations are tested simultaneously in consecutive dermatitis patients.

PATIENTS AND METHODS

Two thousand two hundred eighty-seven consecutive dermatitis patients were patch tested simultaneously with NSH in petrolatum at 2.5% and 5.0%. The allergy rates were compared for all clinics individually and combined using McNemar test, 2-sided.

RESULTS

Contact allergy to NSH 5.0% and 2.5% was found in 20.3% and 16.8%, respectively (P < 0.0001). In 6 of 11 clinics, significantly more patients tested positive to the higher NSH concentration. For the 2 clinics in North America combined, significantly more patients tested positive to NSH 5.0%.

CONCLUSIONS

The NSH preparation in the International Contact Dermatitis Research Group baseline patch test series should be considered to be changed from NSH 2.5% (1 mg NSH/cm2) to 5.0% (2 mg NSH/cm2).

Epicutaneous Patch Testing in Type IV Allergy Diagnostics: State of the Art and Best Practice Recommendations

This chapter summarises all relevant aspects of patch testing, closely following recommendations outlined in a recent European, and a German S3 guideline on diagnostic patch testing with contact allergens and medicinal products (drugs). Patch testing is indicated in patients suspected of suffering, or having been suffering, from delayed-type hypersensitivity leading to allergic contact dermatitis or other skin and mucosal diseases. Sections of this chapter include detailed indications, reasons for possibly postponing the test, considerations on choosing haptens (contact allergens) to test, various aspects of the application of patch test allergen preparations (storage, dosing) and of testing with individual materials provided by the patients. Special aspects of patch testing in cutaneous adverse drug reactions, children, or occupational contact dermatitis are outlined. Supplemental test methods, notably the repeated open application test, are briefly described. Finally, the final evaluation in terms of assessment of clinical relevance of reactions and patient counselling are outlined.

Patch test-relevant concentrations of metal salts cause localized cytotoxicity, including apoptosis, in skin ex vivo

Background

Metal alloys containing contact sensitizers (nickel, palladium, titanium) are extensively used in medical devices, in particular dentistry and orthopaedic surgery. The skin patch test is used to test for metal allergy.

Objective

To determine whether metal salts, when applied to freshly excised skin at patch test–relevant concentrations and using a method which mimics skin patch testing, cause in changes in the epidermis and dermis.

Methods

Tissue histology, apoptosis, metabolic activity, and inflammatory cytokine release were determined for two nickel salts, two palladium salts, and four titanium salts.

Results

Patch test–relevant concentrations of all metal salts caused localized cytotoxicity. This was observed as epidermis separation at the basement membrane zone, formation of vacuoles, apoptotic nuclei, decreased metabolic activity, and (pro)inflammatory cytokine release. Nickel(II) sulfate hexahydrate, nickel(II) chloride hexahydrate, titanium(IV) bis(ammonium lactato)dihydroxide, and calcium titanate were highly cytotoxic. Palladium(II) chloride, sodium tetrachloropalladate(II), titanium(IV) isopropoxide, and titanium(IV) dioxide showed mild cytotoxicity.

Conclusion

The patch test in itself may be damaging to the skin of the patient being tested. These results need further verification with biopsies obtained during clinical patch testing. The future challenge is to remain above the elicitation threshold at noncytotoxic metal concentrations.

A Novel Device that Reduces Preparation Times and Precision Mass Error in Patch Testing for Allergic Contact Dermatitis

BACKGROUND

Patch test preparation for evaluation of allergic contact dermatitis is traditionally a slow process with inherent errors.

OBJECTIVE

A novel device, referred to as a syringer, designed to dispense 10 unique petroleum-based haptens simultaneously, significantly reduces preparation time and increases the precision of the mass dispensed per well.

METHODS

The syringer was custom designed and "printed" through the use of a 3-dimensional printer with a polylactic acid plastic medium.

RESULTS

The syringer dispensed 10 haptens significantly (P < 0.05) faster: 6.9 seconds on average, compared with 29.6 seconds by the traditional method. The syringer demonstrated a significantly (P < 0.05) lower average deviation of each strip's per-well mass average compared with the traditional method.

CONCLUSIONS

In practice, this syringer is ideal for preparing patient-ready patch tests in quantities of 2 identical strips or more.

S3 guidelines: Epicutaneous patch testing with contact allergens and drugs - Short version, Part 1

Epicutaneous patch testing is the diagnostic standard for the detection of allergic contact dermatitis. The present guidelines are aimed at residents and board-certified physicians in the fields of dermatology and allergology as well as other medical specialties involved in establishing the indication for patch testing and its execution in patients with contact dermatitis and other forms of delayed-type hypersensitivity. The target audience also includes other health care providers and insurance funds. Based on a systematic literature search and a formal consensus process (S3), the guidelines were developed by dermatologists in collaboration with pediatricians, occupational medicine physicians, nursing staff as well as patient representatives. The systematic methodological approach and appraisal of evidence upon which the recommendations are based are outlined in a separate method report that also contains evidence tables. The guidelines address general aspects of patch testing as well as medicolegal issues. The recommendations given relate to topics such as the indication for patch testing, informed patient consent, as well as the choice of test substances, test chambers and test site, duration of exposure, reading times and interpretation of test reactions. Furthermore, recommendations are provided with respect to endogenous and exogenous factors, specific patient groups (children, pregnant women, immunosuppressed individuals) as well as possible risks and adverse events associated with patch testing using contact allergens. Note: This publication is part 1 of the short version of the S3 guidelines for "Epicutaneous patch testing using contact allergens and drugs" (registry no. 013 - 018; date: March 20, 2019; valid until December 31, 2021). Part 2 of the short version will be published in the next issue. The long version of these guidelines can be accessed at www.awmf.org. The method report is available as online publication (https://www.awmf.org/leitlinien/detail/ll/013-018.html) and contains the evidence tables in its appendix.

Standardizing the Delivery of 20 μL of Hapten During Patch Testing

BACKGROUND

The current method for patch test tray assembly requires hand dispensing a small volume of hapten onto chambers. Because of human error, this technique produces inaccurate and inconsistent results. The recommended volume of hapten for patch testing using Finn Chambers is 20 μL.

OBJECTIVE

The aims of this study were to create a device that standardizes the delivery of 20 μL and to compare it with the current hand dispensing technique.

MATERIALS AND METHODS

A device, named the Revolution, was created using the SolidWorks program. Five nurses in our Contact Dermatitis Clinic were asked to load 10 Finn Chambers using the current technique and also using the Revolution. Assembly time, volume of petrolatum, and accuracy of placement were measured. After the 3 trials, the nurses completed a survey on the 2 methods.

RESULTS

The amount of petrolatum dispensed using the current technique ranged from 16 to 85 μL, with an average amount of 41.39 μL. The Revolution design dispensed an average of 19.78 μL.

CONCLUSIONS

The current hand dispensing technique does not allow for accurate and consistent dispensing of 20 μL for patch testing. In contrast, the Revolution is an accurate and consistent device that can help standardize the patch testing method.

Isothiocyanates are important as haptens in contact allergy to chloroprene rubber

BACKGROUND

Contact allergy to chloroprene rubber products is well known. Thiourea compounds are considered the cause of allergy. Diethylthiourea commonly occurs in this type of product and can decompose to the sensitizer ethyl isothiocyanate.

OBJECTIVES

To investigate the clinical importance of degradation products and metabolites from organic thioureas in contact allergy to chloroprene rubber with a focus on isothiocyanates and isocyanates.

METHODS

Patients with contact allergy to diphenylthiourea were patch tested with phenyl isothiocyanate and phenyl isocyanate. Patients with known contact allergy to diethylthiourea were retested with diethylthiourea, while chemical analyses of their chloroprene rubber products were performed. The stability of diethylthiourea, diphenylthiourea and dibutylthiourea in patch-test preparations was investigated. Liquid chromatography/mass spectrometry and solid-phase microextraction/gas chromatography were used for determination of organic thioureas and isothiocyanates.

RESULTS

All patients allergic to diphenylthiourea reacted to phenyl isothiocyanate, two of eight reacted to phenyl isocyanate and six of eight reacted to diphenylthiourea. Four patients allergic to diethylthiourea reacted at retest; diethylthiourea was detected in all chloroprene rubber samples, with levels of 2-1200 nmol cm^-2 . At 35 °C, ethyl isothiocyanate was emitted from all samples. Patch-test preparations of diethylthiourea, diphenylthiourea and dibutylthiourea all emitted the corresponding isothiocyanate, with diethylthiourea showing the highest rate of isothiocyanate emission.

CONCLUSIONS

Thiourea compounds are degraded to isothiocyanates, which are generally strong or extreme sensitizers, thus acting as prehaptens. This process occurs in both chloroprene rubber products and patch-test preparations. Positive reactions to phenyl isocyanate indicate cutaneous metabolism, as the only known source of exposure to phenyl isocyanate is through bioactivation of diphenylthiourea.

European Society of Contact Dermatitis guideline for diagnostic patch testing - recommendations on best practice

The present guideline summarizes all aspects of patch testing for the diagnosis of contact allergy in patients suspected of suffering, or having been suffering, from allergic contact dermatitis or other delayed-type hypersensitivity skin and mucosal conditions. Sections with brief descriptions and discussions of different pertinent topics are followed by a highlighted short practical recommendation. Topics comprise, after an introduction with important definitions, materials, technique, modifications of epicutaneous testing, individual factors influencing the patch test outcome or necessitating special considerations, children, patients with occupational contact dermatitis and drug eruptions as special groups, patch testing of materials brought in by the patient, adverse effects of patch testing, and the final evaluation and patient counselling based on this judgement. Finally, short reference is made to aspects of (continuing) medical education and to electronic collection of data for epidemiological surveillance.

Air-oxidized linalyl acetate - an emerging fragrance allergen?

BACKGROUND

Linalyl acetate is a fragrance chemical that is prone to autoxidation. Exposure to linalyl acetate occurs through cosmetic products and essential oils, but is difficult to assess, as linalyl acetate is not labelled in the EU.

OBJECTIVE

To investigate the frequencies of contact allergy to oxidized linalyl acetate among dermatitis patients, and to investigate the autoxidation of linalyl acetate in terms of hydroperoxide formation and sensitization potency.

PATIENTS AND METHODS

Hydroperoxide formation in air-exposed linalyl acetate was determined with high-performance liquid chromatography. The sensitization potencies of hydroperoxides were determined with the local lymph node assay. One thousand seven hundred and seventeen patients were patch tested with oxidized linalyl acetate at 6.0% in petrolatum.

RESULTS

Of the patients, 2.2% showed positive reactions to oxidized linalyl acetate. Forty-three per cent of the positive patients also had positive patch test reactions to other fragrance markers. Linalyl acetate hydroperoxides were detected early in the autoxidation process, and accumulated to a concentration of 37% after 42 weeks of air exposure. The linalyl acetate hydroperoxides were classified as moderate sensitizers.

CONCLUSIONS

The frequency of positive reactions to oxidized linalyl acetate is comparable to that of previously studied oxidized fragrance terpenes. Oxidized linalyl acetate could thus be a common fragrance contact allergen.

Air-oxidized linalool elicits eczema in allergic patients - a repeated open application test study

BACKGROUND

Linalool is a commonly used fragrance terpene that forms potent sensitizers upon oxidation. In a recent multicentre study, we found that 7% of 2900 patients showed positive patch test reactions to oxidized linalool at 6.0%. No elicitation studies have been performed.

OBJECTIVE

To identify threshold concentrations for elicitation of allergic contact dermatitis caused by oxidized linalool in allergic individuals with repeated exposures.

METHODS

Repeated open application tests were performed in 6 participants previously diagnosed with contact allergy to oxidized linalool. Creams containing 3.0%, 1.0% and 0.30% oxidized linalool (corresponding to 0.56%, 0.19% and 0.056% linalool hydroperoxides, respectively) and 'fine fragrance' containing 1.0%, 0.30% and 0.10% oxidized linalool (corresponding to 0.19%, 0.056% and 0.019% linalool hydroperoxides, respectively) were used twice daily for up to 3 weeks. Patch testing with a dilution series of oxidized linalool was performed.

RESULTS

Five of 6 participants reacted to the cream containing 3% oxidized linalool. With 1% oxidized linalool, a reaction was seen in 3 (cream) and 4 (fine fragrance) participants, respectively. With 0.3% oxidized linalool, 2 (cream) and 1 (fine fragrance) participants reacted.

CONCLUSION

Repeated exposure to low concentrations of oxidized linalool can elicit allergic contact dermatitis in previously sensitized individuals.

Unexpected loss of contact allergy to aluminium induced by vaccine

Background

In studies in Gothenburg, Sweden, in the 1990s of an aluminium hydroxide-adsorbed pertussis toxoid vaccine, 745 of ∼76 000 vaccinated children developed long-lasting itchy subcutaneous nodules at the vaccination site. Of 495 children with itchy nodules patch tested for aluminium allergy, 376 (76%) were positive.

Objectives

To study the prognosis of the vaccine-induced aluminium allergy.

Patients and methods

Two hundred and forty-one children with demonstrated aluminium allergy in the previous study were patch tested again 5–9 years after the initial test, with the same procedure as used previously.

Results

Contact allergy to aluminium was no longer demonstrable in 186 of the retested 241 children (77%). A negative test result was more common in children who no longer had itching at the vaccination site; it was also related to the age of the child, the time after the first aluminium-adsorbed vaccine dose, and the strength of the reaction in the first test.

Conclusions

Patch test reactivity to aluminium seems to disappear or weaken with time.

Comparative Study of IQ-Ultra and Finn Chambers Test Methodologies in Detecting 10 Common Standard Allergens that Cause Allergic Contact Dermatitis

Background:

Patch testing is routinely used in contact dermatitis clinics because it is the gold standard for the evaluation of potential allergic contact dermatitis.

Objective:

The study was undertaken to evaluate possible differences in reactivity between the Finn Chamber and IQ-Ultra patch-testing methodologies.

Methods:

Patients were patch-tested simultaneously with the Finn Chamber and IQ-Ultra patch tests. Ten standard allergens set by the North American Contact Dermatitis Group were used for both techniques.

Results:

Both patch tests had a significant agreement in detecting all of the allergens. An “almost perfect agreement” was noted for ethylenediamine dihydrochloride, quaternium-15, mercapto mix, black rubber mix, balsam of Peru, and nickel sulfate; “substantial agreement” for formaldehyde, bisphenol A epoxy resin, and 4-tert-butylphenol formaldehyde resin; and “moderate agreement” for potassium dichromate.

Conclusion:

The Finn Chamber and IQ-Ultra patch tests had a good agreement in the detection of the 10 standard allergens that were tested.

Skin sensitization to p-phenylenediamine: the diverging roles of oxidation and N-acetylation for dendritic cell activation and the immune response

Skin is a target of allergic reactions to aromatic amine hair dye precursors, such as p-phenylenediamine (PPD). As conversion of PPD on or in the skin is expected to be required for the induction of allergic contact dermatitis, we analyzed the role of oxidation and N-acetylation as major transformation steps. PPD and its oxidative and N-acetylated derivatives were tested for their sensitizing potential in vitro using a dendritic cell (DC) activation assay and in vivo using the local lymph node assay (LLNA). PPD did not induce relevant DC activation but induced a positive LLNA response. In contrast, DC activation was obtained when PPD was chemically pre-oxidized or after air oxygen exposure. Under both conditions, the potent sensitizing PPD oxidation product Bandrowski's base was identified along with other di- and trimeric species, indicating that PPD oxidation products provide an effective immune stimulation (danger signal). In contrast mono- and diacetylated PPD did not induce DC activation or a positive LLNA response. We conclude that dermal N-acetylation of PPD competes with the formation of oxidized PPD whereas skin exposure conditions allowing auto-oxidation, as in the LLNA, provide an effective danger signal necessary to induce skin sensitization to PPD.

Mystery of the disappearing allergen: published allergens rarely seen again

Patch testing is an important tool in the diagnosis of allergic contact dermatitis. Although this technique can be accurate, occasionally the results may be inconclusive. A previously positive result to an allergen may become negative upon repeat testing, and this may complicate the process of achieving a definitive diagnosis. There are some potential explanations for such inconsistencies, including the Excited Skin Syndrome, irritant reactions, a need to repeat the diagnostic algorithm, "rogue" reactions, and "contact allergy." These explanations should be taken into account when interpreting these results. However, further knowledge is needed to solve the mystery of an allergen that subsequently disappears.

How to optimize patch testing with diphenylmethane diisocyanate

We have previously shown that patch test preparations of polymeric diphenylmethane diisocyanate (PMDI) are more stable than preparations of diphenylmethane-4,4'-diisocyanate (4,4'-MDI). This study was conducted to (i) investigate whether PMDIs yield as many positive reactions as 4,4'-MDI, (ii) study concurrent reactions to 4,4'-MDI and 4,4'-diaminodiphenylmethane (4,4'-MDA), and (iii) follow the course of positive reactions during 4 weeks. It was shown that PMDIs detect as many positive reactions as 4,4'-MDI. Thus, they are better patch test agents being more stable than preparations of 4,4'-MDI. We recommend that PMDIs with a monomer content of at least 35% is used in 2.0% petrolatum (pet.) (i.e. monomer patch test concentration approximately 0.7%). It was shown that reactions to 4,4'-MDI and PMDIs appear late and we recommend readings on both day (D) 3/4 and D7. 4,4'-MDA was shown to be a good marker for 4,4'-MDI and patch testing with 4,4'-MDA in 0.25% pet. can be used instead of PMDI. Concomitant reactions to 4,4'-MDI and 4,4'-MDA are probably not caused by conversion of 4,4'-MDI into 4,4'-MDA by reaction with water. Another explanation is a path of reactions leading to ureas and MDI conjugates with skin constituents, which are hydrolysed into 4,4'-MDA. This complex process depends upon several factors and might explain why positive MDI reactions appear after D7.

Recommendation of appropriate amounts of petrolatum preparation to be applied at patch testing

BACKGROUND

No recommendation exists on the amount of petrolatum (pet.) preparation to be applied in a Finn Chamber or van der Bend Chamber.

OBJECTIVES

The aim of this study was to determine the appropriate amount of pet. preparation to apply in the Finn and van der Bend chambers.

METHODS

12 volunteers were patch tested with green-coloured pet. in Finn and van der Bend chambers on the back on 3 occasions. Doses were 10, 15, 20, 25, and 30 mg initially and on second and third occasion, 10 mg was removed in van der Bend Chambers and 35 mg was added. On day 2, the test sites were scored. A negative test equalled a test area not covered to 100%. A positive test meant a completely green-coloured test area. Minor and major spreading was noted. The amount of pet. preparation yielding at most 5% negative reactions and having the least number of reactions with major spreading equalled the appropriate amount.

RESULTS

For van der Bend Chambers, all doses yielded more than 5% negative reactions. For the Finn Chamber, 30, 25, and 20 mg pet. yielded less than 5% negative reactions and with major spreading in 60%, 40%, and 25% of test sites.

CONCLUSIONS

20 mg pet. preparation was the optimal dose for the Finn Chambers.