Histological distinction between early allergic and irritant patch test reactions: follicular spongiosis may be characteristic of early allergic contact dermatitis

Comparative light microscopic studies have revealed subtle differences between allergic and irritant reactions in the skin. In the search for specific differences, we focussed on the early inflammatory response. This pilot study was conducted to test the hypothesis that follicular spongiosis can differentiate between early allergic and irritant patch test reactions. 8 patients with known contact allergy to either colophony or quarternium-15 participated in the study. In each patient, allergic and irritant patch tests reactions were elicited, and 4-mm punch biopsies were taken after 6 8 h from clinically equipotent reactions. Paired sets of slides were assessed blindly by 2 pathologists. 1 patient showing a pityrosporum folliculitis was excluded from the study. All biopsies from allergic patch tests were characterized by follicular spongiosis, while biopsies from irritant patch tests showed no recognizable changes except a slight follicular spongiosis in 1 patient. The 2 pathologists agreed independently on the correct classification in 6 out of 7 cases (p=0.0156). We tested an optimized model, selecting non-irritant allergens and a well-known irritant. Further investigations are needed to elucidate the diagnostic significance of the histological classification of allergic and irritant cutaneous reactions in punch biopsies.     

Atopic dermatitis: a histologic and radioautographic study (after 3H-thymidine labelling) of epidermal and dermal lesions (author's transl)]

Skin lesions of atopic dermatitis (A. D.) have been studied histologically and radioautographically after in vitro incorporation of tritiated thymidine. The histopathologic aspects of epidermis in the different types of skin lesions are reviewed. The dermal infiltrate is mononuclear and not very abundant in all types of lesions. An enlargement of the epidermal proliferative compartment has been noticed. Labelled cells are distributed as follows (mean +/- standard deviation) : 46 +/- p. 100 in the basal layer; 37 +/- 6 p. 100 in the epibasal layer; 16 +/- 7 p. 100 in the upper layers. The basal and epidermal labelling indices have been found significantly increased in exudative and lichenified lesions as compared to xerotic areas and normal epidermis. The labelling index of the "round" cell infiltrate in the dermis was significantly higher than in irritant patch test reactions (p less than 0.001) but significantly lower than in allergic positive patch test reactions (p less than 0.001). This increased cell proliferation in the dermal infiltrate does not allow definite conclusions about immunopathogenesis of the disease: indeed, a large number of mediators, involved in the inflammatory reactions of A. D. lesions, can modulate cell proliferation.     

In vivo cytokine profiles in allergic and irritant contact dermatitis

Local cytokine profiles in skin biopsies from allergic and irritant patch test reactions were determined by in vivo immunohistochemistry to differentiate between these 2 clinically identical afflictions especially at the time of final reading in diagnostic patch testing. Biopsies were taken from established allergic persons after specific allergic patch test.-, to epoxy resin (1%) and formaldehyde (1%) and from non-allergic individuals with irritant patch tests to sodium lauryl sulfate (10%) and formaldehyde (8%). At 72 h after application of the agents, significantly enhanced frequencies of dermal infiltrating cells, producing IL-1α, TNF-α. IL-2. and IFN-γ per 100 infiltrating cells in the dermis. were observed in allergic as well us irritant patch test reactions, as compared to normal skin. Significantly higher frequencies of IL- Iα-producing cells were observed in biopsies from epoxy resin (1%) allergen-affected and sodium lauryl sulfate (10%) irritant-affected skin as compared to formaldehyde (1%) allergen-affected skin. In addition, significantly higher frequencies of TNF -α reproducing cells were observed in epoxy resin allergen-affected skin us compared to Formaldehyde (1%) allergen-affected and formaldehyde (8%) irritant affected skin. The allergic and irritant patch test reactions showed similar levels of expression of the Thl cytokines IL-2 and IFN-γ in the dermis. confirmed by probe based detection of IL-2 mRNA and IFN-γ- mRNA, In conclusion, the described similarity shows that allergens and irritants can induce the same profile of IL-la. TNF-α. IL-2. and IFN-γ production, resulting in the near impossibility of discriminating between allergic and irritant contact dermal is at the lime of patch test reading.     

False-positive, follicular and irritant patch teat reactions to metal salts

853 hard metal workers were patch tested with nickel sulphate 5%, potassium dichromate 0.5% and cobalt chloride 1%, each in petrolatum. Non-allergic reactions appeared in 6.5% of the nickel tests, 13% of the chromium tests and 18.3% of the cobalt tests. Most of the individuals with positive, poral or pustular reactions were retested with serial dilutions of metal salts in pet. and in water. The accuracy of a positive initial nickel reaction was 83%, a chromium reaction 40% and a cobalt reaction 62%. The nonallergic reactions were partly reproducible and correlated with both the type of patch test material and with individual factors. Weak and moderately strong positive patch test reactions to metal salts may be irritant and should be checked with serial dilution tests or at least be retested. A reduction of the cobalt chloride concentration from 1% to 0.5% in the standard test material is discussed.     

Prevalence, incidence and course of eczema on the hands and forearms in a sample of the general population

In 1979, the inhabitants of a geographically defined area were examined for skin disorders of the hands and forearms. In 1982 this cohort was invited for re-examination. In persons with eczema, patch testing was performed. Irritant factors were found to play a rôle in 73% of the cases, whereas a contact allergy could be detected in 30%. The must frequent allergens were nickel sulphate (20%), potassium dichromate (6%), land cobalt chloride (4%). In some persons with a definite history of allergy to metals, no positive patch test with nickel, chromate or cobalt could be obtained; other mechanisms may be involved. Significantly more positive patch tests were found among persons with an eczema of longer than 2 years duration compared with persons, with eczema present for a shorter period of time, indicating that many cases of eczema are primarily of irritant nature, but later complicated by sensitisation. In 41%, the eczema was healed. A poor healing tendency was observed in those with a combination or irritant and allergic eczema. Relatively few ascribed healing to medical treatment.     

Immunopathological and ultrastructural findings in human allergic and irritant contact dermatitis

The histopathological features of allergic contact dermatitis were compared with those of irritant contact dermatitis in a group of 17 subjects. Each patient received simultaneous patch tests of a known allergen and a standardized irritant (benzalkonium chloride). The cellular changes occurring between 3 h and 7 days after patch test application were studied by light and electron microscopy and immunocytochemistry. No differences were observed between the induced allergic contact dermatitis (ACD) and the irritant contact dermatitis (ICD), either in the responding cell types or the sequence of cellular events. Both reactions showed a predominantly T lymphocyte infiltrate with no polymorphonuclear leukocyte involvement. Apposition of Langerhans cells to lymphocytes in the epidermis was seen in both types of response. Considerable variability in the intensity of reaction to irritant and allergen occurred within individuals. There was no statistically significant difference between the intensity of the reactions to the irritant and the allergen.     

Alterations of epidermal lectin binding sites in acute contact dermatitis

We investigated alterations of epidermal lectin binding sites, as well as of pemphigus and bullous pemphigoid antigens, in 28 human patch test reactions, both allergic (nickel, formaldehyde, N,N'-1,3-dimethylbutyl-N'-phenylenediamine) and irritant (sodium lauryl sulfate). The epidermal reactivity to a panel of lectins and human antisera to pemphigus vulgaris and bullous pemphigoid antigens was compared with samples obtained from normal skin and from skin under tape occlusion. We observed selective perturbations of lectin and antibody binding in acute contact dermatitis, whether allergic or irritant. The main findings were a loss of terminal sialic acids and longer bi- and triantennary mannosyl residues as well as a loss of pemphigus vulgaris antigen. The only difference between allergic and irritant patch test reactions was in topography of loss of WGA binding sites: in the former, it was most pronounced in the lower and middle epidermis, whereas in the latter it was seen in the uppermost subcorneal layers. Our findings support a common pathway of cell membrane alterations of keratinocytes in acute contact dermatitis.     

The effect of grenz rays on irritant skin reactions in man

To investigate the effect of grenz rays on irritant contact reactions, eleven healthy volunteers were studied. They were given 3 Gy of grenz rays, once a week for 3 weeks, to a defined area of the back. Twenty-four hours after the last treatment, serial dilution sodium lauryl sulphate patch tests were applied both on the grenz ray treated area and on the untreated control skin. Biopsy specimens were taken from the irritant reactions both from the grenz ray treated area and from the control area and different cell populations in dermis and epidermis were identified by monoclonal antibodies (Leu 2, 3, 4, 7, Leu M1, B1, OKT6). In the grenz ray treated epidermis there was a pronounced reduction of OKT6-positive cells but the composition of the dermal cellular infiltrate did not differ between control and grenz ray treated skin. The assessment of the patch test reactions did reveal a tendency towards weaker reactions in the grenz ray pre-treated skin but this difference was not statistically significant. It is concluded that grenz rays do not have a marked effect on the elicitation of irritant reactions.     

Allergic and irritant skin reactions evaluated by laser Doppler flowmetry

Skin blood flow (SBF) in allergic and irritant reactions was determined by laser Doppler flowmetry (LDF) in an attempt to differentiate these reactions in an objective way. 12 subjects with known allergy to nickel were patch tested with nickel sulphate, nickel chloride, and with sodium lauryl sulphate (SLS) 1, 2, 5 and 10%. A positive correlation between the concentration of SLS and SBF was found. Compared with control sites, SBF in weak (+) and strong (++) positive allergic and irritant reactions was increased approximately 5-10 fold 1 and 2 days after application, and decreased towards normal 7 days after application. At day 7, the mean SBF was higher in allergic reactions than in irritant reactions. However, no consistent differences were found. It is concluded that although LDF can be used to quantify the strength of allergic and irritant skin reactions, this method cannot be used solely to separate these 2 types of reaction.     

A comparison of expression of surface-bound immunoglobulin E on antigen-presenting cells in cutaneous tissue between patients with allergic, irritant and atopic dermatitis

The expression of surface-bound immunoglobulin E by dendritic cells within cutaneous tissue has been compared in atopic and contact dermatitis. 45 patients were recruited into 4 groups using clinical criteria and patch testing to a standard series of allergens: atopic (12 cases), allergic contact dermatitis (14 cases), irritant contact dermatitis (10 cases) and the control group (9 cases); using clinical criteria and patch testing to a standard series of allergens. Skin biopsies from each patient were analysed by the indirect immunofluorescence technique. This differentiated 3 patterns of cutaneous IgE distribution: (i) no detectable cutaneous IgE; (ii) detection of IgE solely within the dermis; (iii) detection of IgE within both epidermis and dermis. Detection of IgE within the epidermis was always associated with the presence of IgE within the dermis. In each case, IgE was surface-bound by dendritic cells. Immunoglobulin E was detected within both epidermis and dermis in skin biopsies from 8 (66.7%) atopic patients and 2 (20%) patients with irritant contact dermatitis. No other cases demonstrated IgE deposition within both the epidermis and dermis. Atopic patients were significantly more likely to have detectable IgE deposition, within both epidermis and dermis, than patients with contact dermatitis (allergic and irritant groups combined, p = 0.0011) or controls (p = 0.0049). This finding suggests that the demonstration of IgE within both epidermis and dermis supports a diagnosis of atopic dermatitis. It would therefore be of value in differentiating between atopic and contact dermatitis, where clinical diagnosis is in doubt.     

Artificial disruption of skin barrier prior to irritant patch testing does not improve test design

BACKGROUND: Irritant patch testing is often performed as a 24- or 48-h occlusive patch test with low concentrations of sodium lauryl sulphate (SLS). OBJECTIVES: The aim of this study was to investigate potential ways to shorten this test procedure and obtain precise test results. PATIENTS AND METHODS: Thirty-six healthy volunteers underwent irritant patch testing with different pretreatments (PT) of the test fields. Occlusive test chambers were applied on the upper back with SLS 0.5%, 1%, 2% and 5% in large Finn Chambers(R). The patches were removed after 4 and 24 h, respectively, depending on the concentration used. Test fields were pretreated as follows: PT 0, field without any PT (control); PT 1, prick with lancet; PT 2, prick with test stamp; PT 3, scratch with lancet; PT 4, incision with standardized incision instrument (0.1-0.2 mm depth). Skin reactions were evaluated by transepidermal water loss (TEWL), skin erythema and skin hydration and as well by a visual score (VS) at 4, 24 and 72 h. RESULTS: Our data show an obvious distinction between PT 0-2 and PT 3-4 at all measurement methods. The average TEWL values with PT 3-4 were higher than those with PT 0-2, especially on the 4-h course. This distinction may derive from the shape and size of the skin impairment achieved by PT 3-4, leading to a mechanical barrier disruption. However, SLS may infiltrate directly into deeper skin layers supported by capillarity. Consequently, no or little penetration through the epidermis and interaction with its structures occurs, which is responsible for irritant skin reactions. The SLS dose in the upper skin layers is therefore lower at these PTs. The lower remaining dose of SLS also explains this distinction, especially for the VS. Additionally, there are presumed reactions in deeper layers of the epidermis and dermis at PT 3-4. CONCLUSIONS: In summary, all data suggest a different reaction pattern from the classical irritant response. Therefore, application without any PT seems to be best suited for irritancy skin testing, especially for visual assessment. PTs prior to irritant patch testing have been shown to be unjustifiable.     

Ultrasound for assessment of allergic and irritant patch test reactions

The oedema formation of patch test reactions was quantified by high-frequency ultrasound measurement of skin thickness. Patch testing with nickel sulphate, nickel chloride and sodium lauryl sulphate 1, 2, 5 and 10% was performed in 12 individuals with known nickel allergy. Oedema was greater in allergic than in irritant reactions similar in strength according to the clinical reading. In allergic reactions, the oedema appeared more transcutaneous, while in irritant reactions, more superficial. For differentiation of the 2 types of reaction, application of substances for a 24-h period with measurements the following day is preferable. For rating of allergic and irritant reactions, 48 h of application is preferable with measurements performed on the day patches are removed.     

Differential effects of structurally unrelated chemical irritants on the density and morphology of epidermal CD1+ cells.

In order to gain a greater insight into the complex mechanisms of action of different irritant chemicals on the skin, we have studied the behavior of epidermal CD1+ cells in experimentally induced irritant contact dermatitis. Healthy, human volunteers were patch tested for 48 h with the following six chemically unrelated irritants and their appropriate vehicle controls; benzalkonium chloride, sodium lauryl sulphate, dithranol, nonanoic acid, croton oil, and propylene glycol. After visually assessing and grading the resulting inflammatory reactions, punch biopsies were taken and the morphology and density of CD1+ cells in the epidermis studied using immunocytochemical techniques in combination with image analysis and electron microscopy. Statistically significant decreases in the epidermal density of CD1+ cells occurred in the responses to dithranol (p less than 0.05) and nonanoic acid (p less than 0.01). Importantly, these changes in density were not simply due to variations in the intensity of inflammatory response (r = 0.1157). Alterations in the length of the dendritic processes of CD1+ cells were also induced, and semi-quantitative analysis revealed significant decreases in dendrite length in the reactions to sodium lauryl sulphate (p less than 0.05), nonanoic acid (p less than 0.001), croton oil (p less than 0.05), and dithranol (p less than 0.005). Unlike epidermal density, however, this effect on cell morphology was directly related to the severity of inflammation (r = -0.74, p less than 0.01). Morphologic evidence of cellular injury to Langerhans cells was seen by electron microscopy in the majority of biopsies, although relatively few cells were affected in sodium lauryl sulphate and propylene glycol reactions. Benzalkonium chloride, unlike the other irritants, also induced a state of metabolic activation in a high proportion of epidermal Langerhans cells. Lymphocyte/Langerhans cell apposition was observed in most samples, but was particularly prevalent in the reactions to dithranol. The results of this study demonstrate that significant changes in the morphology and density of Langerhans cells occur in irritant contact dermatitis, some of which are directly influenced by the chemical nature of the irritant.     

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

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

ETAF/Interleukin-1 and epidermal lymphocyte chemotactic factor in epidermis overlying an irritant patch test

We have previously demonstrated that the epidermal content of the lymphocyte activating peptide ETAF/IL-1 and lymphocyte chemotactic factor (ELCF) increases during the development of a cell-mediated immune reaction, represented either by the tuberculin skin reaction or by a positive patch test in patients with contact allergy. The present study describes the epidermal content of these mediators during an irritant patch test reaction. The results show that ELCF, but not ETAF/IL-1, is significantly increased in the epidermis of an irritant patch test with 3% SLS or 5% croton oil, irrespective of the intensity of the clinical patch test reaction. We observed that simple occlusion of epidermis did not induce ELCF activity in healthy persons, whereas patients with previous or current eczema had a significant release of ELCF following such occlusion. These results seem to indicate that there exist important functional differences between allergic and irritant patch test reactions with respect to the presence of lymphocyte activating signals in epidermis.     

Lymphocytes and Langerhans cells in patch tests

The distribution of immunocompetent cells was analysed in allergic (nickel) and irritant (dithranol) patch tests using conventional transmission electron microscopy and labelling with monoclonal antibodies in an avidin-biotin immunoperoxidase study. The biopsies were taken 24 or 48 h after the allergen/irritant application. In allergic and irritant reactions, most inflammatory cells were OKT11 positive (pan T lymphocytes). The majority of these cells were also OKT4 positive (helper/inducer T lymphocytes), while the minority were OKT8 positive (suppressor/cytotoxic T lymphocytes). NK9 positive cells (natural killer cells) were observed in small numbers. The number of dendritic OKT6 and OKIal positive cells (Langerhans cells) in the epidermis was unaffected in allergic reactions. In irritant reactions, a normal number of OKT6 positive Langerhans cells was observed, while the number of OKIal positive cells had increased in the epidermis. Dithranol caused prominent fine structural changes in the mitochondria of the Langerhans cells, while the keratinocytes appeared largely unaffected. The present study indicates that allergic and irritant patch tests cannot be differentiated reliably using current immunohistopathological or electron microscopic techniques, in spite of the small differences observed.     

Olive oil – contact sensitizer or irritant?

Adverse cutaneous reactions to topically applied olive oil are seldom reported, and positive patch tests to it are mostly regarded as allergic. To evaluate such "positive" patch test reactions. 77 female (mean age: 44 years) and 23 male eczema patients (mean age: 46 years) were prospectively patch tested with freshly prepared olive oil. Tests were performed openly (including ROAT) as well as using Al-tests® and Finn Chambers® on Scanpor®. 5 patients (2 male) showed "positive" test reactions (all patients at the Al-test® site. 3 at the Finn Chamber® site. I with ROAT). In only 1 patient could the reaction be classified as probably allergic, in contrast to previous reports. In conclusion, olive oil is very weakly irritant in general, but bears relevant irritant capacity when applied under occlusive conditions. Therefore, olive oil appears to be less than suitable for the topical therapy of patients with venous insufficiency and associated eczema of the lower extremities.     

Multicenter study of preservative sensitivity in patients with suspected cosmetic contact dermatitis in Korea

As many new cosmetic products are introduced into the market, attention must be given to contact dermatitis, which is commonly caused by cosmetics. We investigate the prevalence of preservative allergy in 584 patients with suspected cosmetic contact dermatitis at 11 different hospitals. From January 2010 to March 2011, 584 patients at 11 hospital dermatology departments presented with cosmetic contact dermatitis symptoms. These patients were patch-tested for preservative allergens. An irritancy patch test performed on 30 control subjects using allergens of various concentrations showed high irritancy rates. Preservative hypersensitivity was detected in 41.1% of patients. Allergens with the highest positive test rates were benzalkonium chloride (12.1%), thimerosal (9.9%) and methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) (5.5%). Benzalkonium chloride and chlorphenesin had the highest irritancy rate based on an irritancy patch test performed using various concentrations. Seven of 30 normal subjects had a positive irritant patch reading with 0.1% benzalkonium chloride and eight of 30 normal subjects had a positive irritant patch reading at 4 days with 0.5% chlorphenesin in petrolatum. Although benzalkonium chloride was highly positive for skin reactions in our study, most reactions were probably irritation. MCI/MI and thimerosal showed highly positive allergy reactions in our study. The optimum concentration of chlorphenesin to avoid skin reactions is less than 0.5%.     

Changes in Lymphocyte and Langerhans Cell Populations in Allergic and Irritant Contact Dermatitis

We observed in situ changes in lymphocyte subpopulations and Langerhans cells during allergic and irritant contact dermatitis using immunohistochemical staining methods with monoclonal antibodies to cell surface antigens. In both types of contact dermatitis, there was a perivascular infiltrate of T lymphocytes, with helper/inducer T cells predominating. B cells were absent, and natural killer cells were absent or sparse. During the course of allergic contact dermatitis, Langerhans cells showed a striking sequential change in location, with the cells first in the epidermis, then perivascularly in the dermis (days 1-14), and returning to the epidermis (days 14-21). In irritant contact dermatitis, the Langerhans cells were initially identified in the epidermis and then appeared diffusely in the dermis (days 1-2). The numbers in the dermis then decreased abruptly (day 4). They were again identified in normal numbers in the epidermis (day 21). The response of Langerhans cells appears to be different between allergic and irritant contact dermatitis.     

Irritant dermatitis from tri-butyl tin oxide and contact allergy from chlorocresol

12 patients with known allergy to nickel were patch tested with nickel sulphate, nickel chloride, and sodium lauryl sulphate 1, 2, 5 and 10%. 2 parallel series were performed, i.e., one with 24-h and one with 48-h application time. Reactions were followed by measurement of transepidermal water loss (TEWL). Allergic reactions showed a normal TEWL after 24-h application, and after 48 h, only strong reactions resulted in increased TEWL. In contrast, irritant reactions showed increased TEWL in both series, irrespective of the strength of the reaction. The deficient water barrier of allergic reactions is secondary, probably resulting from the underlying inflammatory process. Consequently, if TEWL measurements are used for the purpose of differentiating allergic and irritant skin reactions, a short application period, i.e., in this study 24 h, is preferable, with recordings performed shortly after removal of test chambers.