Patch testing with a standard allergen ("screening") tray: rewards and risks

Patch Testing Pearls

Dermatitis is one of the most common illnesses encountered by healthcare providers and the causes are numerous. Contact dermatitis is the form of dermatitis resulting from contact with the environment, and it may be either irritant or allergic in nature. Patch testing has been the gold standard for diagnosis of allergic contact dermatitis since its formal description over 100 years ago by Jadassohn. While this diagnostic tool may seem simple to us today, there are numerous potential points for error that the practitioner must keep in mind. Patient selection, technique of patch test placement, allergen selection, patch test reading and interpretation, and patient management all must be considered. To simply apply a given set of test allergens indiscriminately and not be prepared to interpret the results accurately with patient education and management in mind would be a great failure. Conversely, with experience and the proper knowledge base some of the most complex dermatitis questions can be answered.

Hand eczema

Hand eczema is an inflammation of the skin; the cause is often multifactorial. Initial management includes avoiding causative irritants or allergens (e.g., by wearing impermeable gloves) and applying emollients and potent topical glucocorticoids.

A multi-center, retrospective review of patch testing for contact dermatitis in allergy practices

BACKGROUND

Studies assessing patch testing (PT) in allergy practices are limited.

OBJECTIVES

To determine whether PT results using a limited panel of allergens such as in the Thin-Layer Rapid-Use Epicutaneous Test (TT) as compared with an expanded panel, such as the addition of supplemental allergens (North American Contact Dermatitis [NACD] Panel, Dormer Cosmetics, hairdressing series, corticosteroid series, and personal products) will miss a significant number of positive PTs. To compare our PT results with published data from dermatology practices.

METHODS

This is a 5-year multicenter retrospective chart review of PT at 3 separate allergy practices.

RESULTS

Four hundred twenty-seven patients (mean age, 49.8 years) were patch tested. Eighty-two percent were female; 54% reported an atopic history. Of the standardized allergens, the 5 most common positives were nickel sulfate, fragrance mix I, p-phenylenediamine (PPD), thimerosal, and cobalt chloride. Two hundred eighteen (56.9%; 95% CI = 51.9-61.8%) patients were positive to at least 1 TT allergen. Ninety-eight (25.6%; 95% CI = 21.5-30.2%) patients were positive to both a TT and a supplemental allergen. Forty-eight (12.5%; 95% CI = 9.6-16.2%) patients were negative to a TT allergen but positive to a supplemental allergen.

CONCLUSION

Positive allergens would have been missed in 12.5% of patients when evaluating with TT allergens alone, whereas 25.6% would be partially evaluated. Patch test performance characteristics for these allergy practices appear to parallel that seen for dermatology. The TT remains an adequate screening tool in an allergy practice, but a more comprehensive panel may be needed to fully evaluate contact dermatitis.

Allergy skin testing: what nurses need to know

Skin testing is a common procedure in any clinical setting. Critical care nurses will encounter skin testing in the inpatient and outpatient settings primarily to test for patient allergies to environmental factors, or allergies to certain medications. As there is a great deal of controversy about standard practices surrounding the different tests, information about various allergy tests and testing protocols is vital. Quality assurance standards should be met to ensure adequacy of the skin testing technique. Persons performing skin tests should undergo evaluation of their technique. To improve the predictive values of skin testing, and to ameliorate the incidence or severity of adverse affects, it is important for the critical care nurse to understand the dynamics of the test and the possible risks, along with variables that can confound the results. By doing this, nurses will improve not only patient outcomes related to the testing itself but also the value and reliability of the most effective diagnostic tool available for allergic disease.

A central role for transcription factor C/EBP-beta in regulating CD1d gene expression in human keratinocytes

CD1d is a nonclassical Ag-presenting molecule that presents glycolipid Ags to NKT cells that are involved in immune defense and tumor rejection. It also plays a role in immunoregulatory functions in the epidermis. The mechanisms controlling the expression of CD1d are not well understood. Therefore, we cloned the CD1d gene promoter and characterized its activities in primary human keratinocytes and other cell lines of epithelial origin. We found that a CCAAT box in the CD1d promoter is required for its expression in keratinocytes. We show here that transcription factor C/EBP-beta binds to the CCAAT box in the CD1d promoter in vitro and in vivo. Consistent with these observations, deletion of the gene encoding for C/EBP-beta caused a loss of CD1d expression. The in vivo regulation of CD1d has significant implications for the pathologic mechanisms of certain immunologic skin diseases in which NKT cells play a role, such as allergic contact dermatitis and psoriasis. Together, these data show a central role for C/EBP-beta in regulating CD1d transcription.

Th17/Tc17 infiltration and associated cytokine gene expression in elicitation phase of allergic contact dermatitis

BACKGROUND

Allergic contact dermatitis (ACD) is a typical delayed-type hypersensitivity to sensitizing haptens mediated by T cells. Th1/Tc1 cells are currently considered to be the primary effectors in ACD. There is little information concerning the role played in ACD in humans by Th17/Tc17 cells, a recently defined subpopulation of effector T cells.

OBJECTIVES

In the present report we attempted to characterize Th17/Tc17 cells in the infiltrates of the skin in the elicitation phase of ACD.

METHODS

Th17 as well as Th1/Th2 cytokine gene expression was examined by semiquantitative real-time polymerase chain reaction in paired samples of positive patch test biopsies and normal skin from 11 patients allergic to nine different allergens. The in situ characterization of interleukin (IL)-17-producing cells was carried out using anti-RORC and anti-T-cell subset antibodies by double immunofluorescence.

RESULTS

Compared with normal paired skin samples, gene expression of transcription factor for human Th17 cells, RORC, and Th17-related cytokines IL-17A, IL-17F and IL-23 was significantly increased in positive patch test biopsies. The mRNA for interferon-gamma and IL-4 was also increased. In the dermal infiltrates, about 20% of the infiltrating cells were IL-17-producing cells as they expressed RORC, and such RORC-expressing cells were detected in both CD4+ (approximately 30%) and CD8+ (approximately 20%) subsets.

CONCLUSIONS

This is the first demonstration of Th17/Tc17 cells in the elicitation phase of human ACD, showing that they are a regular participant in the immunopathology of this common allergic reaction regardless of the nature of the triggering allergen.

Human natural killer T cells infiltrate into the skin at elicitation sites of allergic contact dermatitis

The purpose of this study is to identify invariant natural killer T cells (NKT cells) in cellular infiltrate of human allergic contact dermatitis (ACD) skin challenge sites. Skin biopsy specimens were taken from positive patch test reactions from 10 different patients (9 different allergens) and studied by immunochemistry, real-time PCR, nested PCR, and in situ hybridization to identify NKT cells and the cytokines associated with this cell type. Invariant NKT cells were identified in all the 10 skin biopsy specimens studied, ranging from 1.72 to 33% of the cellular infiltrate. These NKT cells were activated in all cases, as they expressed cytokine transcripts for IFN-gamma and IL-4. Invariant NKT cells are present in ACD, regardless of the allergen that triggers the reaction, and are in an activated state. We conclude that innate immunity plays a role in late phases of type IV hypersensitivity reactions and may be responding to self-lipids released during allergic inflammation. These data complement the previous work by other investigators that suggest that NKT cells are important in the early cellular response during primary immune responses to allergens. Herein, it is demonstrated that NKT cells are constantly present during the late elicitation phase of human type IV hypersensitivity reactions.

Root canal treatment on a patient with zinc oxide allergy: a case report

AIM

To describe successful root canal treatment of a patient with a true zinc oxide allergy and to discuss allergic reactions to dental materials.

SUMMARY

Dental materials have been reported as aetiologic agents for both local and systemic allergic reactions. It is essential for the oral healthcare provider to recognize the clinical symptoms associated with allergic reactions and to modify dental treatment, if necessary, to prevent these reactions from occurring. This article describes an unusual case of a patient with an allergy to zinc oxide. To our knowledge, this is the first case of successful root canal treatment of a patient with confirmed zinc oxide allergy to be reported in the dental literature.

KEY LEARNING POINTS

Medical and dental histories must be evaluated to prevent medical complications secondary to dental treatment. Any patient suspected of having an allergy to dental materials should be referred to a healthcare professional capable of performing and interpreting allergy tests prior to dental treatment.

Patients' perceptions of the usefulness and outcome of patch testing

BACKGROUND

Studies have shown the effect of allergic contact dermatitis on quality of life, but few address the impact of patch testing.

OBJECTIVE

We sought to determine patient satisfaction with patch testing, patients' perceptions of its usefulness, dermatitis outcomes, and recall of allergens.

METHODS

After patch testing, surveys were mailed to 1453 patients.

RESULTS

Response rate was 52.1%, 757 surveys returned: 518 women (68.4%) and 239 men (31.6%). More than 75% (578) of respondents were at least "somewhat satisfied" with the process; 51% (388) were "very satisfied." More than half (430, 58.3%) reported improved dermatitis. The 580 patients who had positive reactions remembered a mean of 51.0% of allergens; 198 of these (34.1%) remembered 100%. Of 2547 positive reactions to allergens, 1229 (48.3%) were remembered correctly.

LIMITATIONS

Limitations were reporting bias and individual interpretations of questions.

CONCLUSION

Although patients reported both satisfaction with patch testing and improvement in skin conditions, they forgot more than 40% of identified allergens. Techniques are needed to improve patient recall.

Interferon-γ secreted from peripheral blood mononuclear cells as a possible diagnostic marker for allergic contact dermatitis to gold

10% of patch-tested patients have a positive reaction to gold. Most lack clinical symptoms, but allergic contact dermatitis (ACD) to gold is increasing. In this study, 77 dermatological outpatients were divided into 3 groups depending on epicutaneous patch test outcomes: a group positive to gold (EPI+), a group negative to gold (EPI-), and a group with irritant reactions to gold (EPI-IR). Lymphocytes were stimulated in vitro with gold sodium thiosulfate. Proliferation was assessed using the lymphocyte transformation test (LTT), and cytokine secretion was assessed using a multibead array (Luminex; Linco Research Inc., St. Charles, MO, USA), in order to evaluate whether an in vitro method with high diagnostic accuracy could be devised. The EPI+ group showed a significantly increased secretion of interferon (IFN)-gamma, interleukin (IL)-2, and IL-13 and also showed a significantly higher stimulation indexes for LTT, compared to the other 2 subject groups. Sensitivity and specificity were calculated for all methods individually and combined, but IFN-gamma assessment alone was the most accurate method for identifying ACD to gold, with sensitivity and specificity of 81.8% and 82.1%, respectively. This method also identified 87.5% of the EPI-IR subjects as non-allergic. Therefore, assessment of secretion of IFN-gamma should be a valuable complement to patch test for diagnosing gold allergy.

Patch testing: a retrospective analysis of 103 patients with emphasis on practical aspects for the clinician

BACKGROUND

Allergic contact dermatitis is a common dermatologic disorder caused by small chemical molecules that can penetrate the skin barrier. Thousands of chemicals capable of inducing allergic contact dermatitis have been identified. To cure allergic contact dermatitis, the allergen should be identified and eliminated from the environment of the patient. Patch testing, utilizing a variety of standard panels of the most frequent allergens, is used to identify the allergen in question. Patch testing is still the gold standard tool used to identify one or more substances that may contribute to the etiology of allergic contact dermatitis.

OBJECTIVE

To determine the frequency of patch test positivity and to identify the most common allergens in patients with suspected allergic contact dermatitis.

METHODS

A retrospective analysis of files of 103 patients who have been clinically diagnosed to have allergic contact dermatitis and have been patch tested using a standard technique with a Northern American Contact Dermatitis Group series.

RESULTS

Sixty-two patients (60.2%) showed positive reactions to one or more substance. The most common allergens were nickel sulfate, fragrance mix, and neomycin sulfate. There was an increased frequency of positive reactions to fragrance mix and a significant decrease of frequency of thimerosal positive reactions.

CONCLUSIONS

Increased awareness of allergens and their potential sources may help to limit the usage of these chemicals in manufacturing consumer products. This may have contributed to decreased prevalence rates of certain allergens such as thimerosal and paraphenylenediamine.

Patch test results from the Mayo Clinic Contact Dermatitis Group, 1998-2000

BACKGROUND

Patch testing is a diagnostic tool for the evaluation of patients with suspected allergic contact dermatitis. A standard series of allergens similar to that used by the North American Contact Dermatitis Group (NACDG) is used at Mayo Clinic.

OBJECTIVE

Our aim was to report the results of patch testing with a standard series at Mayo Clinic from July 1, 1998, to Dec 31, 2000 and to compare our findings with those of the NACDG during the same period.

METHODS

The results of patch testing with the standard series at Mayo Clinic were examined. Positive reaction rates were compared between Mayo Clinic and the NACDG.

RESULTS

During the 30-month period, 1324 Mayo Clinic patients were patch tested with a standard series of allergens (mean, 60 allergens), whereas the NACDG standard series during this period included 50 allergens. Overall, 917 patients (69.3%) had at least one positive reaction and 606 patients (45.8%) had two or more positive reactions. The 10 allergens used both by Mayo Clinic and by the NACDG that most frequently caused positive reactions were nickel sulfate hexahydrate, balsam of Peru (Myroxylon pereirae), neomycin sulfate, cobalt chloride, fragrance mix, potassium dichromate (0.25%), thimerosal, bacitracin, formaldehyde, and glutaraldehyde. Statistically significant differences in positive reaction rates (P < .05) were observed for 12 of the 43 allergens common to both Mayo Clinic and the NACDG.

CONCLUSION

With large standard patch test series, one can identify commonly encountered and potentially relevant contact allergens.

Improved detection of allergen-specific T-cell responses in allergic contact dermatitis through the addition of 'cytokine cocktails'

The gold standard for the diagnosis of allergic hypersensitivity is skin patch testing with the suspected allergens. This diagnostic tool, however, has distinct disadvantages, and therefore the development of alternative or complementary in vitro tests is of great importance. In this study, we evaluate the applicability of an in vitro test method, as developed earlier for nickel allergy, to detect allergen-specific T cells in the blood of patients allergic to frequent sensitizers (chromate, cobalt, paraphenylenediamine, fragrances and chloromethyl-isothiazolinone). Peripheral blood mononuclear cells (PBMCs) of allergic patients and healthy controls were cultured in the absence or presence of allergen. Additionally, type 1 (IL-7 and IL-12) or type 2 (IL-7 and IL-4) stimulating cytokines were added; after 6-day proliferation, IFN-gamma and IL-5 secretions were determined. Without the addition of cytokines, consistent allergen-induced proliferation was observed in PBMCs of nickel-allergic patients only. By contrast, the addition of type 1 or type 2 stimulating cytokines resulted in a significantly enhanced allergen-specific proliferation for all allergens tested (sensitivity increased from 26 to 43% or 38%, respectively, P < 0.05). In these cultures, allergen-induced IFN-gamma and IL-5 secretion was also significantly increased, compared to healthy controls (P < 0.05, for IFN-gamma sensitivity 79%, specificity 93%; for IL-5 sensitivity 74%, specificity 81%). In conclusion, these results demonstrate an increased proliferative capacity and cytokine production by allergen-specific T cells from allergic patients, but not of healthy individuals upon stimulation with allergens in combination with type 1 or 2 skewing cytokines. The present data warrant further exploration of the application of this test to a broader set of allergens.