7 - Immunogens

BACKGROUND AND OBJECTIVESContact allergy is associated with a significant morbidity all over the world. This study was performed to investigate the pattern of sensitization by contact allergens in the local population.DESIGN AND SETTINGRetrospective study to investigate patch test reactivity among patients with clinical diagnosis of contact dermatitis who were referred to the allergy clinic at the King Khalid University Hospital, Riyadh, between April 2008 and March 2010.PATIENTS AND METHODSOf the 196 patients referred to the allergy clinic over the 2-year period, 91 (46.4%) patients reacted to one or more patch test allergens, and these patients were included in this study. The study group included 82 (91.1%) of Saudi nationality and 9 (8.9%) patients of other nationalities. The patch test was performed using the T.R.U.E TEST, containing 24 allergens/allergen mixes.RESULTSOf the 91 cases who reacted positively to one or more allergens, 67 (73.6%) were females with a mean age of 37 (8.3 years) and 24 (26.4%) were males with a mean age of 34 (11.6 years). Thirty-three (36.2%) patients reacted to nickel sulfate, 14 (15.3%) to p-phenylenediamine, 13 (14.2%) to p-tert-butylphenol-formaldehyde resin, 13 (14.2%) to thimerosal, and 9 (9.8%) to colophony. Reactivity against the rest of the allergens was not remarkable. A significantly higher percentage of females reacted to nickel sulfate (84.8% vs 15.2% in males; P=.0001), p-tert-butylphenol-formaldehyde resin (92.3% vs 7.7%; P=.0001), and thimerosal (76.9% vs 23.1%; P=.03).CONCLUSIONSPatch test reactivity to nickel sulfate was high. The pattern of contact allergy observed in this study indicates the need for large-scale investigations to identify local allergens responsible for contact allergy and for formulation of policies directed towards avoidance of exposure.

We have investigated 115 patients presenting with dermatoses, who worked with cutting oils. The study period was from 1986 to 1987. There were 111 men and 4 women, with ages ranging from 16 to 66 years (mean 42 ± 14.3 years). The final diagnoses were as follows: 28 patients had endogenous hand eczema and irritant contact dermatitis (ICD); 22 allergic contact dermatitis (ACD) and ICD; 21 ICD alone; 19 ACD alone; 12 endogenous hand eczema; 6 other (non-eczematous) conditions; 4 ACD, ICD and endogenous hand eczema; and 3 ACD and endogenous hand eczema. Formaldehyde-releasing biocides were the commonest cause of allergic reactions in the cutting oil series. Reactions were also seen to colophony, formaldehyde, nickel, rubber, dichromate and epoxy resin in the International Contact Dermatitis Research Group (ICDRG) standard series. As 42% of the patients had relevant positive patch tests, patch testing remains an essential investigation in the management of cutting oil dermatitis.

Results of Evaluating Health Care Workers With Prick and Patch Testing

Epidemiological survey of contact dermatitis in Italy (1984–1993) by GIRDCA (Gruppo Italiano Ricerca Dermatiti da Contatto e Ambientali)

Reflectance confocal microscopy may differentiate acute allergic and irritant contact dermatitis in vivo

The diagnosis of combined allergic and irritant contact dermatitis is an accepted subdiagnosis for hand dermatitis, and it is often considered in a patient with contact dermatitis, a positive and relevant patch test result, and wet work exposure. We therefore hypothesize that it is arbitrary for wet work exposure to be taken into consideration in a patient with newly diagnosed relevant contact allergy. Furthermore, an overestimation of the diagnosis will probably occur if the criteria for wet work exposure are applied correctly, as many occupations have an element of wet work. To find the statistically expected number of combined allergic and irritant contact dermatitis cases in 1000 patients, and to evaluate the diagnostic criteria for the diagnosis. One thousand consecutive patients with occupational contact dermatitis from a hospital unit in Denmark were assessed. The expected number of cases with the diagnosis of combined allergic and irritant contact dermatitis was 0.33%, as compared with the observed number of 6.4%. Females occupied in wet occupations were often diagnosed with combined allergic and irritant contact dermatitis (p < 0.005). The diagnosis of combined allergic and irritant contact dermatitis should be used critically to avoid misclassification, and possible criteria for the diagnosis are proposed.

Our understanding of the complex genetic susceptibility to occupational contact dermatitis (OCD) is still in the early stage. The search for candidate susceptibility genes focused mainly on proteins involved in skin barrier and immune response which have a key role in both irritant and allergic contact dermatitis (respectively, ICD and ACD). Furthermore, for ACD genetic variations in enzymes involved in metabolism of contact allergens have been investigated. Among skin barrier genes, lossof- function mutations in the filaggrin gene (FLG) have been identified as a risk factor for irritant contact dermatitis (ICD); the riskmodifying effect of FLG mutations was stronger in the presence of atopic dermatitis. In ACD, the impact of FLG mutations was allergen specific and dependent on the outcome measure and the exposure pattern. Several studies reported association of genetic polymorphisms in the metabolizing enzymes N-acetyltransferase and glutathione S-transferase with ACD; however the results are so far inconclusive. Among inflammatory genes, there appears to be an effect of TNFgene polymorphisms on susceptibility to both irritant and allergic CD, suggesting that they share some common pathways. At present, the predictive value of genetic markers for the appearance of OCD is too low for reasonable identification of susceptible individuals in occupational health practice. Further well-designed studies in larger cohorts with a well-defined disease phenotype and external exposure in the control as well as in the case group are needed to confirm and extend our knowledge of the impact of genetic variations on the susceptibility to OCD.

34 - Contact Dermatitis

Epidemiological studies indicate that occupational hand eczema (OHE) often is associated with persistent dermatitis and prolonged sick leave, which may lead to unemployment. Previous studies suggest that OHE caused by allergic contact dermatitis and atopic dermatitis (AD) carries the worst prognosis. To evaluate and compare the severity and consequences of recognized OHE in different diagnostic and subdiagnostic groups. Between October 2001 and November 2002, all new cases of recognized OHE were identified from the Danish National Board of Industrial Injuries Registry (758 cases). Severity was graded from 0 to 2 depending on the intensity of skin response and the frequency of relapse. To supplement the information from the Registry, we surveyed the study population using a postal questionnaire which included questions about disease duration, sick leave, current occupation and loss of job. The overall response rate to the questionnaire was 82%. We observed substantially greater severity among those with occupational irritant contact dermatitis (ICD) and AD than for any other diagnoses. Age above 50 years was also associated with increased severity of OHE. Prolonged sick leave due to OHE was reported by 19.9% and was associated with AD and severe OHE. We found a higher proportion of prolonged sick leave among those in food-related occupations (27.2%) compared with those in wet occupations (20.1%) and other occupations (16.5%). Twenty-three per cent reported that they had lost their job at least once during the past 12 months due to OHE. The only strong association with loss of job was food-related occupations. Occupational ICD and AD appear to be strongly associated with severity of OHE. AD and severity of OHE were independently associated with prolonged sick leave. Having a food-related occupation appears to be associated with increased risk of loss of job.

Environmental light levels can affect physiological functions, such as general activity, body temperature and metabolism. Irregular lifestyles, such as those involving exposure to light during the night, can exacerbate the clinical symptoms of several inflammatory skin diseases. However, the effects of constant light exposure on immune responses are not fully understood. This study aimed to elucidate the effects of constant light exposure on two major types of skin reactions, allergic contact dermatitis (ACD) and irritant contact dermatitis (ICD). BALB/c mice were kept under constant light conditions or a normal light and dark cycle, and their ACD and ICD responses were assessed after the topical application of 2,4,6-trinitro-1-chlorobenzene and croton oil, respectively, to the ear skin. Interestingly, in both ACD and ICD, the ear-swelling response and local leukocyte infiltration were aggravated by constant exposure to light, which has previously been shown to severely disturb the behavioural rhythms of mice. In ACD, these findings were accompanied by increases in the numbers of degranulated mast cells and eosinophils. These results suggest that constant light exposure intensifies allergic and non-allergic skin inflammation.

Electron Paramagnetic Resonance Study for Defining the Mechanism of Irritant Dermatitis. Irritant Patch Testing in Atopic Individuals. Quantification of Nonerythematous Irritant Dermatitis. Detergents. Permeability of Skin for Metal Compounds. Irritant Dermatitis: Subthreshhold Irritation. Cytokines and Irritant Dermatitis Syndrome. Assay to Quantify Subjective Irritation Caused by the Pyrethroid Insecticide Alpha-Cypermethrin. Prediction of Skin Corrosivity Using Quantitative Structure-activity Relationships. Contamination and Percutaneous Absorption of Chemicals from Water and Soil. Determining an Occupational Dermal Exposure Biomarker for Atrazine Through Measurement of Metabolites in Human Urine by HPLC-accelerator Mass-spectrometry. Partitioning of Chemicals from Water Into Powdered Human Stratum Corneum (Callus). Dermal Exposure of Hands to Pesticides. Iontophoresis. Penetration and Barrier Creams. Fiber. Novel Topical Agents for Prevention and Treatment of Allergic and Irritant Contact Dermatitis. Allergic Contact Dermatitis: Clinical Considerations. Pharmacology, Toxicology and Immunology of Experimental Contact Sensitizers. Modulation of the Dermal Immune Response by Acute Restraint. Textile-dye Allergic Contact Dermatitis Prevalence. Dose-Response Studies in Guinea Pig Allergy Tests. Operational Definition of Allergic Contact Dermatitis. Predictive Immunotoxicological Risk Assessment. Allergic Contact Dermatitis From Transdermal Systems. Animal Models for Immunologic Contact Urticaria and Nonimmunologic Contact Urticaria. Diagnostic Tests in Dermatology. Wound Healing Products. Issues of Toxicity With Dermatologic Drugs During Pregnancy. Roles of Calcium Ions in Skin Barrier. Nuclear Receptors for Psoralen in Cultured Human Skin Fibroblasts. In Vitro Viability Assays. Dermal Penetration of Calcium Salts and Calcinosis Cutis.

When the clinical diagnosis of allergic and/or irritant contact dermatitis is not clear-cut, skin biopsy is considered a useful tool of differential diagnosis. In contrast, biopsies of patch tests are not recommended, except for scientific purposes. Histopathological features of positive allergic patch test reactions are typical of a spongiotic dermatitis, whereas those of positive irritant patch test reactions are varied (mainly epidermal necrosis), depending on the nature and/or concentration of irritant chemicals and the reactivity of the skin. New immunocytopathological techniques are of no help in distinguishing between irritant and allergic patch test reactions, since there is little evidence of differential cytokine release.

Irritant contact dermatitis (ICD) is characterized by direct injury to the epidermal cells, activating the innate immune response. Allergic contact dermatitis (ACD), in contrast, is delineated by a delayed hypersensitivity reaction of type IV. Despite the distinct etiopathogenic mechanisms under-pinning each condition, the differentiation between them presents a significant diagnostic challenge. This study aimed to determine whether a combination of clinical evaluation and noninvasive measurements-encompassing oxidative stress, erythema, hydration, melanin content, transepidermal water loss (TEWL), hemoglobin concentration, and skin texture and volume-could distinguish ICD from ACD. Two cohorts, each comprising 21 patients, were evaluated: one diagnosed with ICD and the other with ACD. All participants underwent biophysical and clinical assessments, along with Antera® 3D evaluations. Tape strips were utilized for skin sampling, and oxidative stress levels were measured via fluorescence assessments. ICD prompted an almost immediate inflammatory reaction (peaking at 24 hours), whereas ACD incited a delayed response (72 hours). Noninvasive evaluated parameters such as hemoglobin concentration, skin texture and volume, melanin content, erythema, and TEWL showed significant differences between the ICD and ACD cohorts (P < 0.05). The allergens amcinonide, nickel sulphate, cobalt chloride, budesonide, PPD, and thiuram mix were found to induce elevated levels of oxidative stress. The evaluation of patients with noninvasive parameters, including transepidermal water loss (TEWL), hemoglobin concentration, and skin texture and volume, could markedly aid in distinguishing irritant contact dermatitis from allergic contact dermatitis (ACD). Nevertheless, the study was constrained by a limited sample size.

Occupational skin disease is one of the most common occupational diseases. The hand is the most frequent site of involvement in occupational skin disease. We interviewed and examined patients seen in the Contact Dermatitis Clinic of the National Taiwan University Medical Center, a tertiary referral center in Taipei City. For patients suspected of having allergic skin diseases, patch testing was carried out using the European standard series and suspected allergens. Occupational hand dermatitis (OHD) was diagnosed according to medical history, work exposure, physical examination, and patch test findings. 36% of patients seen were diagnosed as having OHD. Electronics, hairdressing, medical, chemical, and construction were the most important industries causing OHD. In the 164 patients with OHD, 58.5% had irritant contact dermatitis (ICD) and 41.5% allergic contact dermatitis (ACD). Dorsal fingers, nail folds, and dorsal hands were most frequently involved in patients with ACD; dorsal fingers, volar fingers and fingertips were most frequently involved in those with ICD. Using logistic regression analysis, we were able to identify the most important clinical presentations that predicted the types of OHD, ACD versus ICD. Patients with atopic history and palm involvement were more likely to have ICD, and those with nail fold involvement more likely to have ACD. In patients with ACD, the most important allergens were dichromate, nickel, cobalt, fragrance mix, epoxy resin, thiuram mix, and p-phenylenediamine. In this study, we identified the important industries and causal agents for OHD. Future preventive measures focused on these industries and agents to reduce OHD will be warranted.

Linked articles: COVID‐19 SPECIAL FORUM. J Eur Acad Dermatol Venereol 2020; 34: e210–e216.