Analysis of para-phenylenediamine allergic patients in relation to strength of patch test reaction

Patch Testing to Paraphenylenediamine: The North American Contact Dermatitis Group Experience (1994-2018)

Background/Objectives: Paraphenylenediamine (PPD) is an aromatic amine dye that may cause allergic contact dermatitis. This study examines the epidemiology of allergic patch test reactions to PPD. Methods: This retrospective analysis characterizes individuals tested to PPD (1% petrolatum) by the North American Contact Dermatitis Group (1994-2018). Demographics and dermatitis site(s) were compared between PPD-allergic and PPD-negative patients. PPD reactions were analyzed by reaction strength, clinical relevance, occupational relatedness, and source as well as coreactivity with structurally related compounds. Results: Of 54,917 patients tested to PPD, 3095 (5.6%) had an allergic patch test reaction. Compared with PPD-negative patients, PPD-allergic patients had significantly greater odds of age >40 years (odds ratio [OR] 1.55 [95% confidence interval; CI 1.43-1.69]) and female gender (OR 1.52 [95% CI 1.41-1.66]), but lower odds of being White (OR 0.66 [95% CI 0.60-0.71]). The most common primary anatomic sites of dermatitis were face (25.5%), hands (21.9%), and scattered/generalized pattern (15.5%). Over half (55.3%) of PPD reactions were ++ or +++ at the final reading and 60.9% were currently relevant. Common exposure sources included hair dye (73.5%) and clothing/shoes/apparel (3.9%). Occupationally related reactions occurred in 8.3%, most commonly in hairdressers/cosmetologists (72.8%). The most common coreactions were benzocaine (11.3%), N-isopropyl-N'-phenyl-p-phenylenediamine (6.7%), disperse dye mix (6.5%), and black rubber mix (5.1%). Conclusions: The 24-year percentage of allergic reactions to PPD was 5.6%. PPD allergy was associated with female gender and age >40 years. PPD allergic patients were less likely to be White. Allergic reactions were usually clinically relevant and hair dye was the most frequently identified source.

The expression pattern of N-acetyltransferase 1 in healthy human skin

Background

N‐acetyltransferase 1 (NAT1) is an enzyme expressed among others in keratinocytes in human skin. NAT1 is important in the biotransformation of aromatic amines, an important example being p‐phenylenediamine (PPD), a hair dye molecule. Unoxidized PPD penetrates the skin and is N‐acetylated by NAT1.

Objectives

To investigate in detail the expression pattern of NAT1 in human skin.

Materials and Methods

Cryosections obtained from healthy human skin were stained for NAT1 and expression patterns were observed. NAT1 double stainings were performed with antibodies against different cellular organelles to determine expression patterns.

Result

A speckled, granular expression of NAT1 was seen predominantly in the stratum basale. NAT1 was expressed in a cytoplasmic pattern, perinuclear, and in the nucleus. No co‐localisation was seen with the selected cellular organelles. Local differences in NAT1 expression patterns were observed between donors and between different biopsies obtained from the same donor.

Conclusions

NAT1 is expressed predominantly in the stratum basale and can be found in the cytoplasm, nucleus, and perinuclear in human skin. Further studies should be performed to investigate expression of NAT1 in a larger sample size.

Clinical manifestations of device-related infective endocarditis in cardiac resynchronization therapy recipients

INTRODUCTION

The aim of the study was to analyse microbiological characteristics and clinical manifestations of cardiac device-related infective endocarditis (CDRIE) in cardiac resynchronization therapy (CRT) recipients, and to compare the diagnostic value of modified Duke (MDC) versus modified Duke lead criteria (MDLC; including to MDC local infection and pulmonary infection or embolism as major criteria).

MATERIAL AND METHODS

The study population comprised 765 consecutive CRT patients from a high-volume, tertiary care centre from 2002 to 2015. All patients were screened for CDRIE.

RESULTS

During a median follow-up of 1692 days (range: 457-3067) 5.36% of patients (n = 41) developed CDRIE, which was accompanied by CRT pocket infection in 17.1% (n = 7) and recurrent pulmonary infection or pulmonary embolism in 29.3% (n = 12). Fever was present in 95.1% of patients (n = 39), whereas blood cultures were positive in 65.9% (n = 27). Staphylococcus was the most prevalent pathogen in 59.3% (n = 16), Gram-negative bacteria in 25.9% (n = 7). Transoesophageal echocardiography showed intracardiac vegetations in 73.2% of patients (n = 30). Non-different pathogen types with the most common methicillin-sensitive Staphylococcus aureus were observed for early versus late CDRIE (endocarditis ≤ 6 vs. > 6 months from CRT or other device-related procedure). All 3 inflammatory markers (C-reactive protein, white blood cells, procalcitonin) were normal in 4.9% of patients (n = 2). MDC versus MDLC indicated definite CDRIE in 48.8% versus 80.5%, respectively (p = 0.003).

CONCLUSIONS

Fever is the most common symptom of CRT-related CDRIE, and transoesophageal echocardiography allows vegetations to be visualised in nearly 3/4 of patients with CDRIE. Although the most common pathogens were Staphylococci, Gram-negative bacteria accounted for a quarter of CDRIE. Modified Duke lead criteria proved superior to MDC.

Allergic Contact Dermatitis

Allergic contact dermatitis is common, resulting in considerable morbidity. Diagnosis is based on a thorough history, physical examination, and patch testing. Several commercially available panels of patch testing are currently used. Allergens are found in a wide variety of daily products, occupational exposures, and foods. The mainstay of treatment is avoidance of the allergen, and databases like Contact Allergen Management Program and Contact Allergen Replacement Database help patients to select products that do not contain allergens to which they are sensitized. Topical corticosteroids can be used to treat exacerbations, but should be avoided in long-term treatment.

Allergy Alert Test for p-Phenylenediamine-Allergic Hair Dye Users

BACKGROUND

Contact dermatitis to hair dyes remains a health concern. Regulations in many countries require consumer self-testing for hair dyes, but no standardized procedure exists.

OBJECTIVE

The aim of this study was to develop a self-test protocol for an allergy alert test (AAT) that can elicit a self-noticeable alert signal in p-phenylenediamine (PPD)-allergic consumers.

METHODS

Simulating consumer use conditions (open application for 45 minutes after mixing with a developer), PPD-positive hair dye-allergic subjects and PPD-negative control subjects were tested on the forearm and behind the ear with experimental products containing 0.05%, 0.25%, 0.75%, and 2% PPD. Reactions were self-evaluated by subjects and independently assessed by dermatologists.

CONCLUSIONS

The AAT caused a reaction self-noticeable on the forearm in 90.5% (38/42) and behind the ear in 93% (39/42) of the PPD-positive subjects. This was objectified by a dermatological evaluation. The strength of the AAT response and the number of responding subjects increased with increasing PPD concentrations. Allergy alert test responses were also dependent on the reaction strength of the diagnostic patch test to PPD before the study; in subjects with (+++) patch test reactions, 19 of 19 were positive. All 48 control subjects were negative to the AAT. Therefore, the AAT protocol provides a signal indicative of an allergic reaction in PPD-allergic hair dye consumers.

Cross-elicitation responses to 2-methoxymethyl-p-phenylenediamine in p-phenylenediamine-allergic individuals: Results from open use testing and diagnostic patch testing

BACKGROUND

Allergic contact dermatitis caused by p-phenylenediamine (PPD) is a health concern for hair dye users. Because of its lower sensitization potency, the PPD derivative 2-methoxymethyl-p-phenylenediamine (ME-PPD) has been developed as an alternative hair dye for primary prevention. However, cross-elicitation responses can occur in PPD-allergic subjects.

OBJECTIVES

To compare cross-elicitation responses to ME-PPD in open use and diagnostic patch testing of PPD-allergic subjects with hair dye-related allergic contact dermatitis.

METHODS

Reactions to ME-PPD were investigated in 25 PPD-allergic subjects by performing (1) 45-minute open use testing with a hair dye containing 2.0% of either ME-PPD or PPD, and (2) patch testing with increasing ME-PPD concentrations (0.1%-2.0% pet.).

RESULTS

Of the 25 PPD-allergic subjects, 21 (84%) reacted to open use testing with a hair dye containing 2.0% PPD, and testing with 2.0% ME-PPD led to cross-elicitation in 12 (48%). When patch tested with increasing ME-PPD concentrations, 13 (52%) cross-reacted at 0.1% (lowest dose) and 21 (84%) at 2.0% (highest dose), indicating decreased reactivity as compared with published PPD dose-response data.

CONCLUSION

In line with the decreased cross-reactivity of ME-PPD in hair dye open use testing, PPD-allergic subjects show an attenuated cross-elicitation dose response to ME-PPD in patch testing.

P-Phenylenediamine Hair Dye Allergy and Its Clinical Characteristics

Background

P-phenylenediamine (PPD) has been identified as the most frequent contact sensitizer of hair dye and the clinical characteristics of hair dye contact allergy (HDCA) are diverse.

Objective

The purpose of this study was to identify the clinical characteristics of HDCA and to assess the relationships between HDCA, exposure time to PPD and PPD positivity.

Methods

We analyzed 105 patients with patch test-confirmed hair dye allergy who presented between July 2009 and March 2015. Clinical symptoms, signs, associated skin diseases, involved ACD area, and patterns of hair dye use were obtained by reviewing medical records and by interview.

Results

HDCA was more common in women and in individuals aged more than 50 years. Pruritus was the most common symptom; erythematous macules and patches were the most frequently observed clinical signs. The most common site of HDCA was the face and non-specific eczema and urticaria were frequently observed with HDCA. Exposure time to hair dye, represented as frequency and duration, showed a positive correlation with the area affected by hair dye allergy (p<0.001). Hair dye allergy was identified in most patients (80%) before diagnosis by patch test. However, only 28.6% of all patients stopped using hair dye, even after the diagnosis was confirmed.

Conclusion

The extent of hair dye allergy involvement was related to exposure time to hair dye. For effective treatment of HDCA, it is important to properly educate patients with HDCA about the clinical manifestations of HDCA and to keep away from allergens.

Proposed ICDRG Classification of the Clinical Presentation of Contact Allergy

The International Contact Dermatitis Research Group proposes a classification for the clinical presentation of contact allergy. The classification is based primarily on the mode of clinical presentation. The categories are direct exposure/contact dermatitis, mimicking or exacerbation of preexisting eczema, multifactorial dermatitis including allergic contact dermatitis, by proxy, mimicking angioedema, airborne contact dermatitis, photo-induced contact dermatitis, systemic contact dermatitis, noneczematous contact dermatitis, contact urticaria, protein contact dermatitis, respiratory/mucosal symptoms, oral contact dermatitis, erythroderma/exfoliative dermatitis, minor forms of presentation, and extracutaneous manifestations.

Factors associated with p-phenylenediamine sensitization: data from the Information Network of Departments of Dermatology, 2008-2013

BACKGROUND

Risk factors for p-phenylenediamine (PPD) sensitization include the use of hair dyes, the application of temporary black henna tattoos, working as a hairdresser, and, possibly, exposure to hair dye pretests.

OBJECTIVES

To quantify the impact of these (putative) risk factors on PPD sensitization.

METHODS

Six items related to PPD exposure were added to the routine Information Network of Departments of Dermatology questionnaire from 2008 to 2013. A retrospective analysis of data from 4314 patients tested with PPD 1% pet. was conducted.

RESULTS

Of the PPD-positive patients (n = 271), 80% had their hair dyed, and, of these, 57% subsequently developed scalp dermatitis, whereas only 11% had had a henna tattoo. The self-administrated pretest with hair dye was performed by only a few patients, precluding a more detailed analysis. Hair dyeing [odds ratio (OR) 6.0; 95% confidence interval (CI): 3.9-9.4], henna tattoos (OR 2.4; 95%CI: 1.5-3.7) and being a hairdresser (OR 2.1; 95%CI: 1.3-3.2) increased the risk of PPD sensitization. Neither dyeing of own hair nor application of a temporary henna tattoo seemed to affect PPD sensitization in hairdressers. p-Aminoaryl compounds more often gave positive reactions in patients with henna tattoo.

CONCLUSIONS

Hair dyeing is the major risk factor for PPD sensitization in this clinical setting, and application of a temporary black henna tattoo may also lead to (strong) PPD sensitization.

Diagnosing Allergic Contact Dermatitis Through Elimination, Perception, Detection and Deduction

Several authors have commented upon the skills of detection required in making a diagnosis of allergic contact dermatitis. Here, we emphasise the search for clues in a systematic manner. We describe four stages as part of a systematic method for diagnosing allergic contact dermatitis. Firstly, elimination (or inclusion) of non-allergic diagnoses. Secondly, perception: the pre-patch test diagnosis and the 'three scenarios' principle. Thirdly, detection: optimising the sensitivity of the patch test process. Fourthly, deduction: diagnosing allergic contact dermatitis by associating the dermatitis with the allergen exposure. We further compare and contrast the pre-patch test history and examination with the markedly different one ('microhistory' and 'microexamination') used after patch testing. The importance of knowledge of contact dermatitis literature is emphasised with a review of recent publications. Finally, we also highlight the use of contact allergy profiling as an investigative tool in the diagnosis of allergic contact dermatitis.

Influence of vitamin C on the elicitation of allergic contact dermatitis to p-phenylenediamine

BACKGROUND

Hair dyes represent one of the most important causes of allergic contact dermatitis resulting from the use of cosmetic products. The principal causative chemistry is associated with oxidation products of p-phenylenediamine (PPD) and closely related substances.

OBJECTIVES

To examine whether prior application of the antioxidant vitamin C to the skin was able to reduce the cutaneous allergic response to PPD.

METHODS

Twenty eight volunteers with a proven history of contact allergy to PPD were recruited. Each was tested with a range of PPD doses and PPD-containing hair dye on untreated skin and skin pretreated for 10 min with a vitamin C formulation.

RESULTS

Pretreatment of skin sites with vitamin C led to a reduction in the intensity, or even ablation, of the cutaneous allergic reaction to PPD in ∼75% of cases as compared with untreated skin.

CONCLUSIONS

The results suggest that treatment of the skin adjacent to the hair-bearing area with antioxidant could form part of a strategy to reduce the burden of cosmetic allergic contact dermatitis caused by hair dyeing.

Continuous usage of a hair dye product containing 2-methoxymethyl-para-phenylenediamine by hair-dye-allergic individuals

BACKGROUND

Despite a positive patch test reaction to para-phenylenediamine (PPD) and/or toluene-2,5-diamine (PTD), many people attempt to continue dyeing their hair with products containing PPD or its derivatives.

OBJECTIVES

Investigation of elicitation reactions among PPD/PTD-allergic individuals to hair dye products containing the less sensitizing PPD derivative 2-methoxymethyl (ME)-PPD.

METHODS

Elicitation reactions were studied in 43 PPD/PTD-allergic individuals by a 45-min pretest with an ME-PPD-containing hair dye on their forearm. Upon a negative result this was followed by exposure to subsequent hair colour treatment(s).

RESULTS

Overall, 38 of 43 PPD/PTD-allergic individuals did not develop an elicitation reaction during the pretest with ME-PPD-containing hair dye products, and were eligible for subsequent hair colour treatments. Of these 38 PPD/PTD-allergic individuals, 29 tolerated subsequent hair dyeing with ME-PPD-containing hair dye products, while seven showed mild and two showed moderate/marked allergic reactions upon the first hair colour treatment.

CONCLUSIONS

Hair dye products with the less sensitizing ME-PPD were tolerated by 29 of 43 (67%) PPD/PTD-allergic individuals throughout continued hair dyeing with an average of nine treatments per year. Five individuals reacted upon pretesting, while only mild-to-moderate/marked skin reactions occurred upon hair dyeing in nine individuals who were not identified by the pretest. To our knowledge this is the first study among PPD/PTD-allergic individuals indicating that a negative 45-min pretest with a hair dye product helps to avoid severe allergic reactions.

The role of the antioxidant ascorbic acid in the elicitation of contact allergic reactions to p-phenylenediamine

BACKGROUND

An allergic contact reaction is accompanied by high oxidative stress in the skin. Pretreatment of the skin with antioxidative substances could reduce the elicitation reaction.

OBJECTIVES

To investigate, in a proof-of-principle study, whether pretreatment of the skin with the antioxidant ascorbic acid reduces the elicitation reaction to a p-phenylenediamine (PPD)-containing hair dye in sensitized subjects.

METHODS

Twelve subjects with contact allergy to PPD, a documented skin reaction to a hair dye simulation exposure model and a history of hair dye-related skin complaints were included in this study. Skin areas on the forearms were, in a left versus right design, exposed to an emulsion with ascorbic acid and an emulsion without ascorbic acid, and then to a 2% PPD-containing hair dye testing formulation. In addition, control areas were exposed to the emulsions and to the PPD-containing hair dye formulation without pretreatment. Skin reactions were graded on day (D)2 and D3.

RESULTS

Pretreatment with ascorbic acid emulsion resulted in a reduction in the elicitation reaction in 7 of 12 subjects at D3 (p = 0.046). No statistically significant difference was observed at D2.

CONCLUSIONS

Pretreatment of the skin with the antioxidant ascorbic acid had an attenuating effect on the elicitation reaction to PPD in sensitized individuals.

Contact dermatitis: a practice parameter-update 2015

This parameter was developed by the Joint Task Force on Practice Parameters, which represents the American Academy of Allergy, Asthma & Immunology (AAAAI); the American College of Allergy, Asthma & Immunology (ACAAI); and the Joint Council of Allergy, Asthma & Immunology. The AAAAI and the ACAAI have jointly accepted responsibility for establishing "Contact Dermatitis: A Practice Parameter-Update 2015." This is a complete and comprehensive document at the current time. The medical environment is changing and not all recommendations will be appropriate or applicable to all patients. Because this document incorporated the efforts of many participants, no single individual, including members serving on the Joint Task Force, are authorized to provide an official AAAAI or ACAAI interpretation of these practice parameters. Any request for information or interpretation of this practice parameter by the AAAAI or ACAAI should be directed to the Executive Offices of the AAAAI, the ACAAI, and the Joint Council of Allergy, Asthma & Immunology. These parameters are not designed for use by the pharmaceutical industry in drug development or promotion. Previously published practice parameters of the Joint Task Force on Practice Parameters for Allergy & Immunology are available at http://www.JCAAI.org or http://www.allergyparameters.org.

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.

Hair dye dermatitis and p-phenylenediamine contact sensitivity: A preliminary report

BACKGROUND

The contact allergic reactions from p-phenylenediamine (PPD) in hair dyes vary from mild contact dermatitis to severe life- threatening events (angioedema, bronchospasm, asthma, renal impairment).

OBJECTIVES

To study the clinical patterns and PPD contact sensitivity in patients with hair-dye dermatitis.

MATERIALS AND METHODS

Eighty (M:F 47:33) consecutive patients aged between 18 and 74 years suspected to have contact allergy from hair dye were studied by patch testing with Indian Standard Series including p-phenylenediamine (PPD, 1.0% pet).

RESULTS

54 Fifty-four (M:F 21:33) patients showed positive patch tests from PPD. Eight of these patients also showed positive patch test reaction from fragrance mix, thiuram mix, paraben mix, or colophony. Fifty-seven (71%) patients affected were aged older than 40 years. The duration of dermatitis varied from < 1 month to > 1 year with exacerbation following hair coloring. Forty-nine patients had dermatitis of scalp and/or scalp margins and 23 patients had face and neck dermatitis. Periorbital dermatitis, chronic actinic dermatitis, and erythema multiforme-like lesions were seen in 4, 2, and 1 patients, respectively.

CONCLUSIONS

Hair dyes and PPD constitute a significant cause of contact dermatitis. There is an urgent need for creating consumer awareness regarding hair-dyes contact sensitivity and the significance of performing sensitivity testing prior to actual use.

Analysis of the Results from the Patch Test to Para-Phenylenediamine in the TRUE Test in Patients with a Hair Dye Contact Allergy

Background

Para-phenylenediamine (PPD) is the primary patch test screening agent for hair dye contact allergy (HDCA). However, no recent studies have been published that describe the results of reactions to patch tests using PPD and hair dyes in Korea.

Objective

To analyze the results of the patch tests to PPD using the thin-layer rapid use epicutaneous (TRUE) Test system in patients with HDCA and to investigate patients' awareness that hair dyes contains allergens, which cause the development of HDCA.

Methods

Eighty-four patients with suspected HDCA (32 men and 52 women) underwent patch testing using the TRUE Test system and their own hair dyes. The patients' demographic data, behavior associated with hair dyeing, and clinical manifestations of HDCA were examined retrospectively.

Results

Positive patch-test reactions to hair dyes occurred in 53.6% of patients who used hair dyes, and they were diagnosed with HDCA. Although there was a significant correlation between HDCA and PPD sensitization (p=0.001), only 40% of the patients with HDCA showed positive reactions to PPD. Of the 45 patients diagnosed with HDCA, only 7 (15.6%) were aware that their hair dyes contained allergens that caused HDCA.

Conclusion

This study's findings show that PPD is an effective HDCA marker. However, we propose that investigations on hair dye components other than PPD should be conducted to develop and validate additional predictive HDCA markers.

Allergic contact dermatitis to para-phenylenediamine

Exposure to hair dye is the most frequent route of sensitisation to para-phenylenediamine (PPD), a common contact allergen. International studies have examined the profile of PPD, but Australian-sourced information is lacking. Patients are often dissatisfied with advice to stop dyeing their hair. This study examines patients' characteristics, patch test results and outcomes of PPD allergy from a single Australian centre, through a retrospective analysis of patch test data from 2006 to 2013 at the Liverpool Hospital Dermatology Department. It reviews the science of hair dye allergy, examines alternative hair dyes and investigates strategies for hair dyeing. Of 584 patients, 11 were allergic to PPD. Our PPD allergy prevalence rate of 2% is at the lower end of international reported rates. About half these patients also react to para-toluenediamine (PTD). Affected patients experience a significant lifestyle disturbance. In all, 78% tried alternative hair dyes after the patch test diagnosis and more than half continued to dye their hair. Alternative non-PPD hair dyes are available but the marketplace can be confusing. Although some patients are able to tolerate alternative hair dyes, caution is needed as the risk of developing an allergy to other hair dye ingredients, especially PTD, is high.

Positive relationship-intensity of response to p-phenylenediamine on patch testing and cross-reactions with related allergens

BACKGROUND

Hair dye exposure is the most common cause of sensitization to p-phenylenediamine (PPD). Cross-reactions with structurally related allergens occur.

OBJECTIVES

It is suggested that a stronger patch test reaction (3+ rather than 1+) to PPD (usually tested as 1% petrolatum) is associated with an increased propensity for cross-reactions. In this article we will demonstrate this association.

METHODS

Of 230 patients with allergic reactions to PPD on patch testing identified during 2007-2012 from clinical records, notes for 221 were available for review. Data were collected regarding age, sex, and grade of reaction [International Contact Dermatitis Research Group (ICDRG) criteria] to PPD. Cross-reactions with the following allergens, found in our baseline series, were recorded: Disperse Yellow 3, N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and caine mix. Having excluded 23 doubtful reactions, the reactions from 198 patients were further considered.

RESULTS

Of the patients, 75.3% (n = 149) were female, and the mean age was 48.6 years (12-82 years). Of the patients allergic to PPD, 16.6% (n = 33) showed cross-reactions with one or more related allergens. Cross-reactions were seen in 16% with a grade of 1+, 14.5% with a grade of 2+, 28.6% with a grade of 3+ when PPD was tested 1% pet., and 50.0% when PPD was tested at 0.1-0.001%, arbitrarily considered to be 4+ (p = 0.02; Cramér's V = 0.23).

CONCLUSION

An increasing likelihood of reactions to Disperse Yellow 3, IPPD or caine mix was seen with increasing strength of patch test reaction to PPD. The clinical relevance of these cross-reactions is unclear.

Allergic contact dermatitis: epidemiology, molecular mechanisms, in vitro methods and regulatory aspects. Current knowledge assembled at an international workshop at BfR, Germany

Contact allergies are complex diseases, and one of the important challenges for public health and immunology. The German ‘Federal Institute for Risk Assessment’ hosted an ‘International Workshop on Contact Dermatitis’. The scope of the workshop was to discuss new discoveries and developments in the field of contact dermatitis. This included the epidemiology and molecular biology of contact allergy, as well as the development of new in vitro methods. Furthermore, it considered regulatory aspects aiming to reduce exposure to contact sensitisers. An estimated 15–20% of the general population suffers from contact allergy. Workplace exposure, age, sex, use of consumer products and genetic predispositions were identified as the most important risk factors. Research highlights included: advances in understanding of immune responses to contact sensitisers, the importance of autoxidation or enzyme-mediated oxidation for the activation of chemicals, the mechanisms through which hapten-protein conjugates are formed and the development of novel in vitro strategies for the identification of skin-sensitising chemicals. Dendritic cell cultures and structure-activity relationships are being developed to identify potential contact allergens. However, the local lymph node assay (LLNA) presently remains the validated method of choice for hazard identification and characterisation. At the workshop the use of the LLNA for regulatory purposes and for quantitative risk assessment was also discussed.

Severe allergic reactions to para-phenylenediamine in children and adolescents: should the patch test concentration of PPD be changed?

BACKGROUND

Semipermanent henna tattoos containing para-phenylenediamine (PPD) are a well-known cause of severe contact dermatitis, mainly in children. Another relevant exposure source to PPD are hair dyes, which are increasingly used by children and have also been reported to cause intense facial and scalp dermatitis. German patch test guidelines for children recommend that PPD should only be tested in patients who have had a henna tattoo, and then at a reduced concentration of PPD 0.5 % for 24 hours.

PATIENTS AND METHODS

We report on patch test results in four patients, three children and one adolescent, with a history of contact dermatitis to henna tattoos or hair dye. We used the recommended or even lower patch test concentrations of PPD with 24-hours exposure in all patients.

RESULTS AND CONCLUSION

All patients showed very strong patch test reactions to PPD and cross-reactions to related compounds even after dilution of PPD to as low as 0.05 %. Therefore, we suggest that in children with a history of allergic reactions to this compound, a titration test should be performed beginning at a concentration of maximal 0.05 %. This procedure has also been proposed previously based on a larger cases series in adults.

Elicitation of the immune response to p-phenylenediamine in allergic patients: the role of dose and exposure time

BACKGROUND

Usage of hair dye products containing p-phenylenediamine (PPD) is a concern for PPD-allergic individuals.

OBJECTIVES

The present study investigates the role of dose and exposure time on elicitation of allergic contact dermatitis under conditions of permanent hair dyeing.

METHODS

Elicitation responses after application of a typical hair dye product containing 2% PPD for 30 min followed by rinsing were analysed in 38 PPD-allergic individuals with a documented history of hair dye-related allergy. Skin binding experiments in vitro were performed to distinguish the dose available for elicitation from the dose applied.

RESULTS

A positive reaction was elicited in 20 of 20 patients with grades ++ to +++ and 12 of 18 with grade + according to the classification of the International Contact Dermatitis Research Group. Under conditions of diagnostic patch testing (48 h exposure), the dose available for elicitation is more than 10-fold higher compared with the dose available for hair dyeing (30-min exposure, rinsing of product).

CONCLUSIONS

This investigation demonstrates that under simulated hair dye use conditions the actual exposure to PPD is more than an order of magnitude lower than under diagnostic patch testing, although sufficient to elicit a clearly noticeable reaction in 84% of PPD patch test-positive individuals.

p-Phenylenediamine sensitization is more prevalent in central and southern European patch test centres than in Scandinavian: results from a multicentre study

BACKGROUND

Positive patch test reactions to p-phenylenediamine (PPD) are common. PPD is used in oxidative hair dyes and is also present in dark henna temporary 'tattoos'. Cross-sensitization to other contact allergens may occur. Because subjects sensitized to PPD are at risk of clinically severe reactions upon hair dyeing, there is a need for 'current' prevalence data on PPD sensitization.

OBJECTIVES

To compare PPD patch test results from dermatitis patients tested between 2003 and 2007 in 10 European patch test centres and to analyse the causes and determine relevance of positive PPD patch test reactions.

MATERIALS

Patch testing was performed using PPD (1% free base in petrolatum from Trolab (Almirall Hermal GmbH, Reinbeck, Germany) or Chemotechnique (Malmö, Sweden), equivalent to 0.090 mg/cm(2) in the TRUE test from MEKOS Laboratories AS). Statistical analysis was performed using the chi-squared test.

RESULTS

The weighted average prevalence was 4.6% among 21 515 patients. PPD sensitization occurred more often in centres located in Central and Southern Europe than in Scandinavian centres (odds ratio = 2.40; 95% confidence interval = 2.07-2.78). The overall proportion of positive patch test reactions to PPD that were registered as being of either current or 'past' relevance was high (weighted average 53.6% and 20.3%, respectively). Consumer hair dyeing was the most prominent cause of PPD sensitization (weighted average 41.8%). Furthermore, occupational hair dye exposure (10.6%) and cross-sensitization to textile dyes (12.6%) were frequently reported.

CONCLUSIONS

PPD sensitization caused by exposure to hair dyes is frequent and remains a present problem for patients visiting contact dermatitis clinics, especially in patch test centres located in Central and Southern Europe.

Characterization of p-phenylenediamine-albumin binding sites and T-cell responses to hapten-modified protein

Exposure to p-phenylenediamine (PPD) is associated with the development of T-cell-mediated allergic contact dermatitis. The purpose of this study was to define the nature of the interaction of PPD with the protein and the antigenic determinant that stimulates T cells. Mass spectrometry was employed to show that PPD oxidation products bind irreversibly to cysteine (Cys, position 34) in human serum albumin (HSA). A modified tryptic peptide was characterized with an increase in mass of 106 Da, corresponding to the addition of PPD and not to the secondary products of self conjugation. Lymphocytes from 10 PPD-allergic patients, but not tolerant/naive individuals, were stimulated with PPD and PPD-modified HSA. A total of 70 PPD-specific and 10 PPD-HSA-specific CD4+, CD8+, and CD4+CD8+, Th2-secreting T-cell clones were generated from three allergic patients. In total, 40 clones were stimulated with both PPD and PPD-modified HSA. PPD-modified HSA triggered T-cell responses through a classical hapten mechanism involving processing. Presentation of PPD to several clones was dependent on protein complex formation (42 out of 48) and processing (32 out of 68); however, 12% of clones were triggered with PPD directly. These data identify Cys as the single target for PPD-HSA binding, and show that PPD protein adducts are antigenic determinants in patients with contact dermatitis.

Epidemiological data on consumer allergy to p-phenylenediamine

Many women and men now dye their hair. p-Phenylenediamine (PPD) is a frequent and important component of permanent hair dye products; exposure to it may cause allergic contact sensitization, acute dermatitis, and severe facial oedema. To increase our understanding of PPD allergy, we reviewed published literature containing PPD patch test data from dermatitis patients and individuals in the general population. This was performed to estimate the median prevalence and the weighted average of PPD sensitization and thereby assess the burden of PPD-containing hair care products on health. Literature was examined using PubMed-MEDLINE, Biosis, and Science Citation Index. The median prevalence among dermatitis patients was 4.3% in Asia, 4% in Europe, and 6.2% in North America. A widespread increase in the prevalence of PPD sensitization was observed among Asian dermatitis patients. In Europe, a decrease in the 1970s was replaced by a plateau with steady, high prevalences ranging between 2% and 6%. The prevalence remained high in North America, although a decreasing tendency was observed. Contact allergy to PPD is an important health issue for both women and men. More stringent regulation and enforcement are required as public health measures to reduce the burden of disease that exposure to PPD has brought to populations.

Investigation of the immunogenicity of p-phenylenediamine and Bandrowski's base in the mouse

p-Phenylenediamine (PPD) exposure is associated with T-cell mediated contact dermatitis. T-cells from allergic patients proliferate following exposure to PPD and the oxido-conjugation product Bandrowski's base (BB). Both compounds are classified as sensitizers in the local lymph node assay; however, because of their instability the nature of the antigenic determinant remains ill-defined. The aim of this study was to explore the immunogenic potential of PPD and BB in mice. Spleen cell proliferation and cytokine secretion was measured ex vivo following antigen recall with soluble PPD or BB and either irradiated or glutaraldehyde fixed, antigen pulsed dendritic cells from syngeneic mice. Glutathione was added to certain incubations. LC-MS analysis and solvent extraction were used to monitor the fate of [(14)C]BB in culture and the extent of BB binding, respectively. Spleen cells from BB exposed, but not PPD- or vehicle-exposed, mice proliferated when stimulated with BB. Proliferating cells secreted high levels of IFN-gamma, GM-CSF and IL-2. Stimulation with PPD instigated low levels of proliferation. Irradiated, but not fixed, dendritic cells pulsed with BB stimulated proliferation signifying a classical hapten mechanism involving irreversible BB binding to protein and processing. BB bound preferentially to serum protein when incubated together with cells and serum. Degradation of BB in the presence of glutathione was associated with a stronger stimulation of specific T-cells at higher BB concentrations. These data demonstrate that BB is a potent immunogen in the mouse.

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.

Polysensitization and increased susceptibility in contact allergy: a review

Genetic factors presumably play a role in contact allergy (CA). There is, however, a lack of conclusive evidence from clinical studies. This may be on account of the strongly competing or modifying impact of exogenous factors, namely the potency of allergens and the intensity of exposure, and the fact that - in principle - everybody can be sensitized. Regarding phenotype, in contrast, polysensitization (PS) seems to indicate a subset of individuals at greater risk. In human sensitization experiments with dinitrochlorobenzene, induction was facilitated in PS, and elicitation enhanced. Recent clinical epidemiological data, taking confounders for PS, such as age, sex, and other skin diseases into account, demonstrated the following: (i) PS was the greatest risk factor to be sensitized to a number of (even weak) index allergens, indicating higher susceptibility on the level of induction; (ii) patch test reactions in PS patients were generally stronger indicating higher susceptibility on the level of elicitation. These findings are complemented by reports on polymorphisms of TNF-alpha and IL-16 in PS patients. Future studies on the genetics of CA should be performed in subgroups with PS, focussing on polymorphisms relevant for CA-specific and nonspecific (inflammatory) processes.

Intermittent exposure to low-concentration paraphenylenediamine can be equivalent to single, higher-dose exposure

Hair dye allergy is an important and increasingly common cause of allergic contact dermatitis. The role of repeated exposure in elicitation of allergy has not previously been extensively studied. We have therefore compared elicitation between single and intermittent exposure to paraphenylenediamine (PPD). 23 subjects known to be allergic to PPD from positive patch tests were exposed to 0.3% and 0.03% PPD, both in petrolatum and water, for 5 min at the same site every day for up to 8 D. In the same subjects, single exposures were also performed at different sites, from 5 to 40 min. Other experiments exposed rat skin to radiolabelled PPD as one-off application or multiple exposures. There were 8 reactions in the cumulative exposure site using 0.3% PPD in aqueous solution. In 7 of these, there was an exact correlation with reaction to the cumulative time needed for repeat exposures to elicit a reaction and the time needed for a reaction to the single exposure. There were no reactions to 0.03% PPD in water or pet under either type of exposure condition. There was also a positive correlation between grade of original reaction in clinic (+++, ++, +) and appearance/intensity of elicitation reactions. In the animal study, cumulative time and single exposure time sites correlated with regards to retention of radiolabelled substance within the skin. This study therefore demonstrates for the first time that, over the time period tested, the allergenic component of PPD accumulates in the skin. Hence, intermittent exposure to lower concentrations of PPD may be equivalent to higher concentration, one-off exposure.

Elicitation response characteristics to permanent hair dye in paraphenylenediamine-allergic volunteers

BACKGROUND

Elicitation response characteristics to complete permanent hair dye products in paraphenylenediamine (PPD)-allergic volunteers have not previously been explored in detail.

OBJECTIVES

To assess the elicitation response characteristics observed in PPD-allergic volunteers upon patch testing with complete hair dyes.

METHODS

PPD-allergic volunteers were assigned to 1 of 3 groups depending upon whether they elicited + (group 1), ++ (group 2) or +++ (group 3) reactions following the standard diagnostic procedure. Each group was subsequently patch tested with 2 complete hair dyes (A and B) for 30 min, 1 hr and 24 hr. Patch sites were examined 1 day, 2 days and 3 days after patch removal.

RESULTS

Exposure to either hair dye for 30 min or 1 hr was insufficient to yield positive patch test reactions in all of the PPD-allergic patients in groups 1 or 2. Application of either hair dye for 24 hr was sufficient to yield positive reactions in all of the individuals within groups 2 and 3.

CONCLUSIONS

The frequency of positive patch test reactions observed following 24-hr exposure to complete permanent hair dyes is comparable to that observed following 48-hr exposure to 1% PPD/petrolatum in those individuals whose degree of sensitization is such that they typically present ++ or +++ reactions diagnostically.