Search

The murine local lymph node assay is a method for predictive testing of contact allergenicity, but its ability to discriminate between allergens and irritants has been questioned. To explain some of the conflicting results with irritants, the proliferation induced by methyl salicylate and nonanoic acid, both considered to be non-sensitisers, was further investigated. Both substances showed a dose--response relationship and clearly positive results when tested at higher concentrations (> or = 50%) and would thus be classified as potential sensitisers according to the present criteria for a positive assay result. In the case of methyl salicylate, the use of either dimethyl formamide or methyl ethyl ketone as vehicle did not significantly influence the results. The negative results obtained for methyl salicylate in some earlier reports were probably due to testing at too low concentrations. The proliferation induced by irritants such as methyl salicylate and nonanoic acid and inter alia sodium dodecyl sulfate, Triton X-100, oxalic acid, chloroform/methanol (2:1) must be better recognized and elucidated before the assay can be generally accepted as a predictive test method.

During recent years several highly developed non-invasive methods for evaluation of skin physiology and pathology have been introduced. Against this background, the present studies were undertaken with the primary aim of assessing the effects of various skin care products on some properties of the skin. Skin topography was measured by profilometry on skin replicas, friction with a newly developed friction instrument, capacitance with a Corneometer, and barrier function both with an Evaporimeter to assess transepidermal water loss (TEWL) and by application of an irritant followed by measurement of the resulting irritative reaction. Initially some of the techniques were used to further characterize the differences between dry atopic skin and normal skin. Dry skin exhibits increased values of roughness parameters and a reduced number of topographical peaks. TEWL is increased, indicating impaired barrier function. The friction and capacitance are lower and correlate significantly to each other, whereas TEWL does not appear to relate to either of these parameters. The use of a scrub cream removes the outermost part of the stratum corneum, resulting in a smoother skin. Application of moisturizers modifies the frictional response of the skin. The friction instrument gave results comparable to those of panelists trained in sensory evaluation. The study suggests that measurement of skin friction can be used to predict the degree of liking of moisturizers. Furthermore, moisturizers increase the skin hydration. They provide water directly to the skin from their water phase. Skin hydration also increases with increased degree of occlusion, as measured as a decrease in TEWL. Moisturizers may also alter the diffusional resistance of the stratum corneum and reduce the skin susceptibility to the surfactant sodium lauryl sulphate (SLS). Lipids in moisturizers may influence already developed SLS-induced irritation. A significantly lower degree of irritation was found in areas treated with canola oil and its sterol-enriched fraction than in an area treated with water. These findings emphasize that skin care products do not only form an inert, epicutaneous layer, but that they may penetrate and influence the structure and function of the skin.

commercially available, highly standardized, ready-to-use test withnickel sulfate andpotassiumdichromate patchtests attached synchronously to both sides of the back of patients with a history system (TRUE-testâ ) with randomized location of the allergens. Using a double-blind study design 589 patients with a of nickel allergy, conducted with a highly standardized randomized test system (TRUE-testâ ). Out of 589 patients tested, a history of nickel allergy were tested with 2 of the most common standard allergens that have a diŒerent potential to elicit total of 388 had responded with allergic reactions to nickel sulfate and 130 to potassium dichromate. The reproducibility of allergic, questionable and irritant reactions, i.e. nickel sulfate and potassium dichromate. positive nickel (dichromate) patch tests was 99.2% (90.8%). The reaction index was also calculated, which relates the number of allergic reactions obtained with a test preparation to the number MATERIAL AND METHODS of questionable and irritant reactions; the reaction index can range from ‐1 (questionable and irritant reactions only occur) Thirteen centres of the German Contact Dermatitis Research Group contributed data from a double-blind study approved by the local to 1 (allergic reactions only occur). For nickel sulfate the Ethical Committees. Patch-test patients older than 17 years with a reaction index was 0.91, but it was only 0.23 for potassium history of nickel allergy (reported eczematous reactions to skin contact dichromate, as a result of considerably more questionable reac- with metal likely to contain nickel or positive nickel patch test) were tions. In conclusion, a highly synchronous reproducibility of enrolled after giving their informed consent. Exclusion criteria were results can be achieved by using a well-standardized patch-test as follows: any kind of immunosuppressive medication, treatment of the back with ultraviolet (UV) light or corticosteroids within 4 weeks system, especially withnickel sulfate. However, distinct allergens prior to testing, ineammatory dermatoses of the back, any major

Intradermal microinjection of the pruritogen histamine, or the algogen capsaicin, in the mouse cheek differentially elicits mainly hindlimb scratching or ipsilateral forelimb wiping, respectively. We investigated the dose-dependency of these responses elicited by various pruritogens and algogens, and µ-opioid modulation. Histamine, 5-hydro-xytryptamine (5-HT) and agonists of protease-activated receptors PAR-2 and PAR-4, all elicited dose-related hindlimb scratching bouts with little forelimb wiping. In contrast, capsaicin, allyl isothiocyanate and bradykinin elicited dose-related forelimb wiping with little scratching. Morphine reduced capsaicin-evoked wiping but not pruritogen-evoked scratching. The µ-antagonist naltrexone decreased pruritogen-evoked scratching but not capsaicin-evoked wiping. A cowhage spicule inserted intradermal elicited equivalent scratching and wiping, while inactivated cowhage spicules loaded with histamine or capsaicin elicited significantly more scratching or wiping, respectively. The mouse cheek injection model appears to be a useful behavioral test that distinguishes between itch and pain.

Our clinical experience has suggested that the presently recommended patch-test concentration (1.0%) for formaldehyde in the baseline series might be too low. Therefore, consecutively patch-tested dermatitis patients were tested simultaneously with formaldehyde 1.0% and 2.0% (w/v) in aqua. Formaldehyde 1.0% and 2.0% were applied with a micro-pipette (15 microl) to filter paper discs in Finn Chambers (0.30 mg/cm(2) and 0.60 mg/cm(2), respectively). A total of 1397 patients with dermatitis were patch-tested. In all, 68 (4.9%) patients reacted positively to formaldehyde; 37 reacted only to 2.0%, 29 reacted to both concentrations, and 2 reacted only to 1.0%. Significantly more patients were thus diagnosed with contact allergy to formaldehyde 2.0% compared with 1.0% (p < 0.001). We detected 0.1%, 0.4%, and 29.6% irritant reactions to 1.0%, 2.0%, and 3.0% formaldehyde, respectively. We conclude that, with an optimized patch-test technique, doubling the dose per area detects significantly more contact allergies to formaldehyde, but an even higher test concentration causes too many irritant reactions to be usable.

Moisturizers are often used in the prevention and treatment of irritant contact dermatitis. The present study was to determine whether long-term daily use of a moisturizer on normal skin would affect skin barrier function, hydration state, or susceptibility to sodium lauryl sulphate. Healthy volunteers used a moisturizer on one forearm 3 times daily for 4 weeks. The other forearm served as a control. Afterwards both forearms were challenged with a patch-test of sodium lauryl sulphate. Skin barrier function was evaluated by measuring trans-epidermal water loss and skin hydration by measuring electrical capacitance. Electrical capacitance was significantly increased on the treated arm during the treatment period. After challenge with sodium lauryl sulphate, transepidermal water loss was significantly higher on the arm treated with moisturizer than on the control arm. The results suggest that long-term treatment with moisturizers on normal skin may increase skin susceptibility to irritants.

Expression of serotonin (5-hydroxytryptamine; 5-HT), 5-HT receptors 1A (5-HT1AR) and 2A, and serotonin transporter protein (SERT) was studied in positive epicutaneous reactions to nickel sulphate in nickel-allergic patients, at 72 h post-challenge with the antigen. In addition, the effects of 5-HT2AR agonist 2,5-dimethoxy-4-iodoamphetamine (DOI), and the selective serotonin reuptake inhibitors (SSRIs) citalopram and fluoxetine, were tested on nickel-stimulated peripheral blood mononuclear cells from nickel-allergic patients, regarding their proliferation and interleukin (IL)-2 production, as well as the effect of these SSRIs on a murine Langerhans' cell-like line (XS52), regarding its IL-1beta production. Serotonin-positive platelets were increased in the inflamed skin compared with control skin. A decrease (p

Persistent post-occupational dermatitis is a phenomenon that is well-recognized by occupational dermatologists, but there have been few studies on it. In view of this, we proposed to assess the prevalence of this phenomenon in an English setting and ascertain the characteristics of the patients affected. Using modified criteria adapted from previous studies, details of 1100 patients seen in a contact dermatitis clinic were screened. Persistent post-occupational dermatitis was diagnosed in 5 patients out of 1100 seen over a 35-month period in a contact clinic (4 women, 1 man; age of onset 19-52 years). All had hand dermatitis that persisted despite removal of the apparent causative agents. Four patients were nickel-allergic on patch testing, though nickel was thought to be a potential causative agent in only one case and 2 patients were allergic to thiuram-mix on patch testing, and in both thiuram had a possible causative role. In all 5 cases, irritant exposure seemed important, with allergic factors contributing in 3 cases. Two patients had had eczema in childhood. Persistent post-occupational dermatitis is uncommon, affecting less than 0.5% of patients seen in a contact dermatitis clinic, but when diagnosed it has major implications for the future employment prospects of the individuals concerned.

Adaptation of the skin to repeated influence of exogenous irritants is called the hardening phenomenon. We investigated the stratum corneum lipid composition before and after induction of a hardening phenomenon. Irritant contact dermatitis was induced in 23 non-atopic volunteers by repeated occlusive application of 0.5% sodium lauryl sulfate (SLS) over 3 weeks. At 3, 6 and 9 weeks after irritation, the SLS responses of pre-irritated skin and normal skin were compared. The horny layer lipid composition (ceramides 1–7, cholesterol and free fatty acids) was assessed before irritation and 3, 6 and 9 weeks after irritation. During the first 2 weeks of irritation the transepidermal water loss increased continuously and seemed to decrease during the third week (effect of adaptation). The barrier function of pre-irritated sites was more stable to SLS challenge. Three weeks after irritation, there was a significant increase of ceramide 1 (pv0. 001). The only volunteer without hardening phenomenon showed no increase of ceramide 1. Ceramide 1 seems to play a key role as a protection mechanism against repeated irritation. Key words: hardening phenomenon; irritant contact dermatitis; stratum corneum lipids; ceramides; transepidermal water loss.

Combined exposure to different irritants in the workplace may lead to irritant contact dermatitis, which is the main type of occupational dermatitis among bakers and confectioners. Following previous work on "tandem irritation", a panel of healthy volunteers was exposed twice daily for 4 days to the organic fruit acids: citric, malic, and lactic acid, either alone or in tandem application with 0.5% sodium lauryl sulphate (SLS) in a repetitive irritation test. Irritant cutaneous reactions were quantified by visual scoring and non-invasive measurement of transepidermal water loss and skin colour reflectance. Twice daily application of either citric or malic acid alone did not induce a significant irritant reaction. Combined exposure to one of the fruit acids and SLS caused marked barrier disturbance, but the latter irritant effect was smaller than that obtained by combined exposure to SLS and water. Thus, combined exposure to the above-mentioned fruit acids and SLS did not enhance cumulative skin irritation.

Contact dermatitis simulating erythema multiforme can be caused by many allergens. The chemical agent 1,2-ethanedithiol, which serves as a protective group in chemical synthesis, has hitherto only been implicated as an irritant. We report on a 22-year-old female chemistry student who developed widespread erythema multiforme-like lesions after local contact with 1,2-ethanedithiol. Many target lesions were observed bilaterally on her hands, forearms, arms, and on her forehead. One such lesion was histologically compatible with erythema multiforme. The patient had a positive patch test to 1,2-ethanedithiol, whereas none of 30 healthy subjects showed a positive reaction. However, eight of the 30 controls (26.7%) developed irritant reactions to 1,2-ethanedithiol. Cautious handling of the compound is a prudent precaution.

The pathomechanism of atopic eczema is complex. Two of the most important exogenous factors for atopic eczema are allergenic and irritant substances. In this study we investigate the combined effect of topical aeroallergens and irritation on the skin of atopic individuals. We performed patch testing with several aeroallergens (atopy patch test) and with an irritant, sodium lauryl sulphate, on clinically unaffected skin of 30 sensitized patients with atopic eczema. Application was conducted alone and as a consecutive application. Healthy volunteers served as controls. Evaluation was made by measurement of transepidermal water loss 2 h after removal of the patches. In atopic patients, we found increased levels of transepidermal water loss induced by the aeroallergens as well as by sodium lauryl sulphate. The most impressive barrier disruption was seen after application of house dust mite, followed by cat dander and grass pollen. However, the consecutive application of aeroallergens and sodium lauryl sulphate led to a highly pronounced increase in transepidermal water loss. Hence, in sensitized atopic subjects the combined effect of aeroallergens and detergents may cause severe skin problems, and this may be relevant in daily practice.

The effect of a protective cream was tested in a new tandem repeated irritation test with tandem application of 0.5% sodium lauryl sulphate (SLS) and undiluted toluene. The irritants were applied twice daily for 30 min to the ventral forearms of 20 volunteers. Irritant cutaneous reactions were quantified by a visual score, transepidermal water loss, chromametry and skin capacitance. Concurrent application of SLS/toluene induced stronger reactions than those caused by twice daily application of each irritant on its own. A protective effect of the protective cream was obtained against all treatment combinations and was significant for SLS/SLS (p < or = 0.01) and SLS/ toluene (p < or = 0.05). Our results indicate that the tandem repetitive irritation test has great potential in the evaluation of skin care products to prevent irritant contact dermatitis.

Irritant contact dermatitis has a broad spectrum of clinical features and is a leading cause of occupational disease worldwide. It has been shown previously that a combination of chemically different irritants may cause an additive effect compared to single application of these substances. In this study, tandem application of sodium lauryl sulfate and n-propanol was investigated in 20 human volunteers using non-invasive bioengineering methods, such as measurement of transepidermal water loss and chromametry. N-propanol did not enhance cumulative skin irritation when used with sodium lauryl sulfate, as has been reported for toluene. As n-propanol is the active ingredient in many disinfectants, this is of particular interest regarding occupational skin irritation in health care workers.

Perfluoropolyethers (Fomblin HC products) are chemical non-reactive polymers with special physico-chemical properties that recently showed promise as protective preparations in the prevention of irritant contact dermatitis. We evaluated the efficacy of a new class of perfluoropolyethers (perfluoropolyether phosphate, Fomblin HC/P2) in the prevention of experimentally induced cumulative irritant contact dermatitis if applied prior to irritation. A panel of 20 healthy volunteers was tested with a repetitive irritation test using 4 standard irritants (sodium lauryl sulphate of highest purity, sodium hydroxide, lactic acid and toluene) in a randomized double-blind study. Application sites were assessed clinically and by the use of bioengineering techniques (transepidermal water loss and chromametry). Three gel preparations each containing 5% perfluoropolyether phosphate showed significant efficacy against irritation due to sodium lauryl sulphate and sodium hydroxide, while one test preparation containing 2% showed inferior benefit, indicating a dose-related effect. Preparations containing perfluoropolyether phosphates can be recommended for workplaces with water-soluble irritants. Further studies under real workplace conditions are indicated.

Allergic contact dermatitis and irritant contact dermatitis have different pathogenic mechanisms. It is therefore plausible that the epidermal expression of HLA-DR and the invariant chain associated with antigen processing and presentation might differ between allergic contact dermatitis and irritant contact dermatitis. We have quantified the volume of epidermal HLA-DR and invariant chain reactivity and the total epidermal volume in allergic contact dermatitis and irritant contact dermatitis using confocal laser scanning microscopy and indirect immunofluorescence on acetone-fixed 25 microns thick vertical skin sections. Eight nickel allergic patients were patch-tested with 5% nickel sulfate and 8 healthy volunteers were patch-tested with 4% sodium lauryl sulfate. Skin biopsy specimens were taken at 0, 6, 24, and 72 h after application of the patch tests. Sodium lauryl sulfate induced a statistically significant increased epidermal volume at 24 h and 72 h compared to 0 h and 6 h (p < 0.003 and p < 0.001, respectively), whereas an increase in epidermal volume in the allergic contact dermatitis group was not noted until 72 h after patch testing with nickel sulfate compared to 0, 6 h (p < 0.001) and 24 h (p < 0.004). No significant changes in the epidermal volume of HLA-DR reactivity were found at any time point within or between the two groups, nor was there any significant change in the epidermal volume of invariant chain reactivity in the allergic contact dermatitis group. In the irritant contact dermatitis group, however, the epidermal volume of invariant chain reactivity was significantly reduced from 17 +/- 8 x 10(3) microns 3 at 24 h to 9 +/- 3 x 10(3) microns 3 at 72 h (p < 0.04), which was also significantly lower than the 14 +/- 4 x 10(3) microns 3 observed in allergic contact dermatitis at 72 h (p < 0.01). Furthermore, the invariant chain expression was significantly lower than the HLA-DR reactivity in the irritant contact dermatitis group at 72 h (p < 0.001). The decrease of invariant chain reactivity at 72 h in irritant contact dermatitis might reflect an epitope-induced alteration by sodium lauryl sulfate or a down-regulated biosynthesis of the invariant chain due to variance in local cytokine production between allergic contact dermatitis and irritant contact dermatitis.

The effect of 3 protective creams and petrolatum was tested in a repetitive irritation test. On 15 healthy volunteers, the irritants (sodium lauryl sulfate 10%, sodium hydroxide 0.5%, lactic acid 15%, and toluene undiluted) were applied on the paravertebral skin of the mid-back after 30 min pretreatment with the products tested. The volunteers were treated for 9 days. The irritant cutaneous reactions were quantified by erytbema score, transepidermal water loss, and chromametry. The results showed a specific profile of efficacy against the 4 irritants used. For all creams a significant protective effect was obtained against irritation by sodium lauryl sulfate, sodium hydroxide and lactic acid in different degrees. Less efficacy was observed against toluene. Even an amplification of inflammation by pretreatment with 1 product could be demonstrated. The results indicate that a 1-week period of cumulative irritation might be enough to evaluate the efficacy of protective creams against most irritants.

It is desirable to further evaluate the clinical relevance of a positive patch test. The repeated open application test (ROAT) has been suggested as such a supplementary method. To compare the results of patch testing with the outcome of ROATs, 13 colophony-sensitive subjects and 9 controls were patch-tested with colophony in a serial dilution test. Five microliters, of three concentrations of a colophony solution and the vehicle were then applied to small test areas on the lower arm, once daily for 2 weeks. Prior to each application, all test sites were examined visually and with bioengineering techniques. In the ROATs, 10/13 colophony-sensitive subjects--but no controls--reacted to a 20% colophony solution, 4 also 1%. A correlation was found between the threshold concentration at patch testing and the outcome of ROATs. There was great variation in the reactivity in the ROATs. Objective measures for evaluating the ROAT reactions gave no further information than visual assessment.

Because of the increasing need of reliable skin irritation tests and in order to reduce the number of animal experiments, in vitro alternatives have to be developed. We studied four surfactants and five metal salts for their cytotoxic potency in HaCaT cells, a spontaneously immortalized human keratinocyte line. The endpoint used to assess cellular viability was metabolization of the tetrazolium salt XTT (2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide). The tested substances revealed a significant rank order of their cytotoxicity at an exposure time of 24 h. It was 1) benzalkonium chloride, 2) sodium lauryl sulphate, and 3) Tween 20 (polyoxyethylene sorbitanmonolaurate) and Tween 80 (polyoxyethylene sorbitanmonooleate), for the surfactants; and 1) potassium bichromate, 2) copper sulphate, 3) cobalt chloride and palladium chloride, and 4) nickel sulphate, for the metal salts. There is an excellent correlation to the rank order of their known irritative potency in vivo. Being practicable and effective, the presented XTT-assay on HaCaT cells would be well suitable for an initial orientating screening of substances, subsequently followed by irritation tests directly in humans.

To reduce the incidence of irritant contact dermatitis, the development of screening methods to identify subjects with increased susceptibility to irritants is essential. In a pilot study on the comparison between two quick, non-invasive irritancy tests (dimethyl sulfoxide (DMSO) and sodium hydroxide (NaOH) with the time-consuming patch testing with sodium lauryl sulphate (SLS), no correlation between the "quick tests" and SLS patch testing was observed. In the present paper the results of irritancy testing in 181 metal worker trainees are presented. Experimental irritant contact dermatitis reactions were induced on the medial third of the volar forearm using SLS 0.5%, applied for 23 h and as "quick tests" DMSO 90% and 95% and a solution of 0.2% mol/l NaOH applied for 5 min. Assessment of skin irritability was made by visual scoring and measurement of transepidermal water loss. Except for a statistically significant relationship between the irritations by DMSO 90% and 95%, correlations between the different techniques were weak or non-existent. This is most probably due to different pathophysiological pathways for the irritant reactions. We therefore propose to use a spectrum of different tests in occupational dermatology for predicting the individual's risk of irritant contact dermatitis.

Besides visual evaluation, skin irritation induced by sodium lauryl sulfate (SLS) may be characterized by bioengineering measurements, such as skin colour reflectance, transepidermal water loss (TEWL) or hydration. Short application times or low concentrations of the irritant usually do not modify the visual aspect of the skin, and the measurements described above are unchanged or only slightly altered. We were looking for a suitable method to measure cutaneous changes not detectable by usual bioengineering procedures. Therefore these measurements were compared to those of dynamic function testing of the stratum corneum, namely sorption-desorption and moisture accumulation tests. Different concentrations of SLS (0.1%, 0.5%, 2.5%), application times (15 min, 24 h) and times of testing (1 h, 24 h after patch removal) were investigated on the ventral forearm of human subjects. When SLS was applied for a short period (15 min), 1 h after patch removal skin colour, TEWL and hydration were not modified, while increases in hygroscopicity, water-holding capacity and water accumulation were detected depending on the applied concentration. Increase of hygroscopicity was closely correlated with the alteration of epidermal barrier function (TEWL). We demonstrated that sorption-desorption and moisture accumulation tests performed on SLS-treated areas for a short period, without visible modifications, could evaluate changes of the stratum corneum properties. We consider these tests as useful complementary methods to skin colour, TEWL and hydration measurements, particularly in the detection of subclinical skin injuries.

Cyclophosphamide given before allergen and recombinant interleukin-12 administered at the time of allergic sensitization substantially increase the acquisition of allergic contact dermatitis in the mouse. Since their immunoadjuvant mechanisms appeared different, it seemed probable that combining cyclophosphamide pretreatment with interleukin 12 administration would result in a more intense allergic contact dermatitis than when either agent was used alone. This was tested in different groups of mice sensitized to dinitrofluorobenzene or to oxazolone. Consistently, immunopotentiation of allergic contact dermatitis was significantly greater with the two immunoadjuvants than with either alone. This immunoadjuvant combination is likely to find use in immunization protocols designed to induce a Th-1 helper cell response.

Cis-urocanic acid, converted from trans-urocanic acid in stratum corneum by ultraviolet B irradiation, has been shown to impair contact hypersensitivity induction. To study whether topical cis-urocanic acid also alters contact hypersensitivity elicitation, as well as immediate hypersensitivity and acute irritation, we treated mice with 1% topical cis-urocanic acid or vehicle prior to induction or elicitation of hypersensitivity to contact allergen oxazolone or respiratory allergen trimellitic anhydride or prior to acute irritation from croton oil. Topical cis-urocanic acid suppressed both induction and elicitation of contact hypersensitivity to oxazolone. However, no effect by cis-urocanic acid on induction or elicitation of trimellitic anhydride allergy or croton oil irritation was seen. The possible efficacy of topical cis-urocanic acid as a treatment of inflammatory skin diseases responsive to ultraviolet B irradiation may be worthwhile to investigate.

While assessing the protective effect of broad-spectrum sunscreens against chronic UVA radiation, we observed a paradoxical worsening of skin damage with one product. To further examine this finding, five proprietory broad-spectrum sunscreens were applied to albino hairless mice irradiated thrice weekly for 32 weeks with a UVASUN lamp (340 nm). Appropriate age-matched controls were included. After approximately 12 weeks, two sunscreens induced a marked dermatitis. Biopsies showed damage greatly exceeding that found in UVA-irradiated, unprotected controls. Histologically, elastic fibers were hyperplastic, coalescing into elastotic clumps. Glycosaminoglycans also increased. Collagen damage was notable since UVA alone does not induce a histologic change. Electron microscopy confirmed these findings. Two other sunscreens provided nearly complete protection. Against chronic UVB radiation, the two UVA photoirritating sunscreens provided substantial protection. Since the UVA sunfilter, oxybenzone, was the same in all sunscreens, we postulate that an irritating component of the vehicle was responsible for the UVA-induced photoirritation. The fifth sunscreen produced severe damage with UVB and UVA.

Zinc therapies exert beneficial effects in several cutaneous pathologies through their antiinflammatory properties, but target cells and mechanisms of action are still uncertain. We wondered whether markers of the keratinocyte activation state, such as the expression of immune surface antigens (ICAM-1 and HLA-DR) and the production of TNF-alpha, frequently detected in inflammatory reactions, may be reduced by zinc. For this purpose, we used normal human keratinocytes derived from plastic skin surgery and cultured in low-calcium medium (MCDB153). We studied the effects of ZnSO4 (12.5 to 50 microM) alone or in combination with IFN-gamma (5 U/ml), a mediator of inflammation produced by activated T-cells, or nickel (5-10 micrograms/ml), a sensitizing metal hapten. Using FACS analysis, we showed that the combination of zinc with nickel or the addition of ZnSO4 24 h before IFN-gamma or NiSO4 treatments reduced ICAM-1 expression on the keratinocyte surface (p0.01). However, zinc did not modify the IFN-gamma induced expression of HLA class II antigen on keratinocytes. Zn2+ could also reduce the TNF-alpha secretion of keratinocytes stimulated by IFN-gamma or Ni2+ during 48 h. Taken together, these data indicate that zinc can directly reduce some keratinocyte activation markers frequently observed in vivo; this action may be involved in the antiinflammatory effect of Zn(2+)-associated therapies in cutaneous inflammatory reactions.

The aim of this study was to establish an objectively assessable procedure simulating simultaneous exposure to irritants and allergens in domestic and occupational environments, in order to evaluate differences in the reactivity to the combination of these substances in atopic and non-atopic nickel-sensitized subjects. Thirty-four nickel-sensitive patients, 20 of whom were affected by atopic dermatitis, underwent four patch tests with NiSO4 0.05% aq. on two adjacent sites of both volar forearms, with a 24-h application time. Two of the test sites were treated with sodium lauryl sulfate (SLS) 5% for 30 min, before application of the nickel sulfate preparation. Echographic recordings were performed by a 20-MHz B-scanner and processed by an image analysis program, providing a numerical representation of the picture data, based on the attribution of fictional values to the amplitudes of the echoes. The dermal inflammatory reaction was quantified by an amplitude band, marking the hypo-reflecting part of the dermis, whereas epidermal damage was assessed by a band highlighting the entrance echo. Pre-treatment with SLS of the skin area where nickel sulfate was subsequently applied greatly enhanced the allergic response at 24 and 72 h, both in subjects with atopic dermatitis and in subjects with allergic contact dermatitis. However, in atopics, the increase in the allergic reactivity after irritation of the skin was more pronounced both by clinical and by echographic evaluation. These observations stress the importance of the concurrent action of irritants and allergens in maintaining the dermatitis in atopics.

The murine local lymph node assay is a new predictive test for identifying contact sensitizers. It measures the proliferative response in the lymph nodes during the sensitization phase. In the present study, moderate-to-extreme allergens (from human and guinea pig experience) gave clearly positive results in this assay. However, irritants tested, i.e. sodium dodecyl sulphate (SDS), chloroform/methanol, oxalic acid, triton X-100 and methylsalicylate, also gave positive results, not distinguishable from the results with low-grade/moderate allergens. Two allergens were also tested in the presence of 10% SDS. The effect on proliferation was additive in the first case and synergistic in the second. The local lymph node assay in its present design and with the criteria used for a positive response requires further validation studies and perhaps further development before it can be accepted as an alternative to guinea pig tests for allergenicity. Substances with exclusively irritating properties could falsely be classified as allergens by the method or, alternatively, the allergenicity of chemicals with both allergenic and irritating properties could be overestimated.

The ability of dithranol and 10-butyryl dithranol to induce morphological cell transformation was studied in cultured C3H 10T1/2 C18 fibroblasts. The cells were incubated with different concentrations of the test compounds for 48 h and cultured for 5 weeks thereafter. At the end of the culture period the cultures were fixed, stained and examined for the presence of transformed foci. Dithranol and 10-butyryl dithranol did not increase the formation of transformed foci, while the positive control compound, 7,12-dimethylbenz(a)anthracene (DMBA), induced a high frequency of transformations significantly different from controls. Thus the in vitro cell transformation model with uninitiated C3H 10T1/2 C18 fibroblasts is not able to detect the weak tumorigenic action of dithranol and 10-butyryl dithranol which has been observed in mouse skin.

Delayed hypersensitivity retest reaction 3 and 6 weeks after induction of allergic and irritant inflammation, was studied in 13 females with known hypersensitivity to nickel. An increased retest reaction compared to controls was observed only in sites of earlier specific allergic inflammation. Also a general down-regulation of the degree of hypersensitivity was observed at retesting.

Nickel contact sensitivity was successfully induced in guinea pigs using an open epicutaneous application method. Immediately after pretreatment with 1% aqueous sodium lauryl sulfate, upper back skin was treated daily for 4 weeks with 0.3%-3% nickel sulfate in either a 1% lanolin cream (Vaseline, pH 5 SAD crème) or hydroxypropyl cellulose. Weekly intradermal injections with aluminium potassium sulfate were used as adjuvant. The animals were challenged twice with a one week interval, with nickel sulfate 2% in water and 1% in petrolatum, respectively. The response rates in the test groups treated with nickel sulfate 1% or 3% in the lanolin cream or 1% in hydroxypropyl cellulose were significantly different from the response rate in the control group. Considering both readings at both challenges, the frequency of sensitization was 57-93% (8 of 14 to 13 of 14 animals) in the group treated with 1% in the lanolin cream, 60-100% (9/15 to 15/15 animals) in the group treated with 3% in the lanolin cream, and 67-75% (8/12 to 9/12 animals) in the group treated with 1% in hydroxypropyl cellulose. Rechallenge of initially sensitized animals 10 weeks later confirmed that a lasting contact allergy had been obtained.

Normal human skin was exposed to two different detergents, sodium lauryl sulphate in distilled water and non-anoic acid in isopropanol at different concentrations. The detergents were applied under occlusion in epicutaneous tests for 24 h and biopsies were taken at 24 or 48 h. Frozen sections were labelled with monoclonal antibodies against CD1a, CD3 and ICAM-1. The evaluation of the labelled sections showed that there were differential effects on the expression of ICAM-1 and CD1a+ cells in epidermis. After non-anoic acid application ICAM-reactivity could not be detected and there was a decrease of staining for CD1a after exposure to 80% non-anoic acid. Sodium lauryl sulphate treatment, however, induced ICAM-1 expression on keratinocytes and had minor effects on the number of CD1a+ cells. ICAM-1 expression was also detected in normal epidermis in 3 of 9 unexposed control biopsies and after occlusion with the vehicles distilled water and isopropanol. An increased amount of CD3+ cells was found in the skin exposed to both detergents. The results show that there are dose and time dependent variations in the epidermal response to irritants which might influence the immunological events taken place in the epidermis.

Superoxide generation by blood monocytes was examined in patients with irritant, nickel, and chromate hand dermatitis. Phorbol myristate acetate stimulated monocytes generated significantly more superoxide in patients with nickel dermatitis, as did patients with hand eczema generally. No significant stimulation of monocyte superoxide generation occurred with either opsonized zymosan or PMA in the presence of excess superoxide dismutase in any of the groups of hand dermatitis. The results indicate a biochemical stimulation of superoxide which may accentuate the immunological damage in the skin that is observed in nickel and perhaps chromate dermatitis.

The cytokine expression on epidermal cells in the allergic patch test reaction (APR) and irritant patch test reaction (IPR) was studied using antibodies against rIL-6, rTNF alpha, rIL-1 alpha and rIL-1 beta in a histochemical biotin-avidin technique. Nickel sulphate was used for APR in 5 nickel allergic patients and sodium lauryl sulphate for IPR in 5 healthy individuals. The individuals served as their own control. Enhanced keratinocyte expression of IL-6 was observed in APR and IPR, whereas staining for TNF alpha remained unaltered compared with non-tested and petrolatum-tested skin. Staining for IL-1 alpha and IL-1 beta proved negative in all specimens. Double-staining experiments demonstrated that epidermal and dermal OKT-6 (CD1) positive Langerhans cells (LC) remained negative for all cytokines. These results demonstrate that enhancement of keratinocyte-bound IL-6 does not induce TNF alpha, IL-1 alpha/beta or IL-6 expression by LC during APR or IPR, and that enhanced keratinocyte expression of IL-6 fails to distinguish between these two reactions.

The aims of the investigation were: 1) to study the inter-individual variation in time course of TransEpidermal Water Loss and of clinical manifestations after a 24-h single exposure to Sodium Lauryl Sulphate. This TEWL time course (expressed as the difference in TEWL between the day of patch removal and a subsequent day) reflected the epidermal barrier response to the damage caused by SLS; 2) to investigate the association between the TEWL time course after the single SLS exposure and the TEWL value after 4-day repeated SLS exposure (as a model for cumulative irritation). The 35 healthy subjects tested could be divided into four sub-groups according to the day of their maximum TEWL value after the single SLS exposure (days 2 to 5). For the whole group, inter-individual variation in TEWL course was most pronounced in the first days following the single SLS application. Moreover, there was an inverse relationship (R = -0.61) between TEWL course during the first days after the single exposure and the TEWL value after 4-day repeated exposures. It is concluded that this association illustrates the importance of an adequately responding barrier function against the continuous exposure to irritants in daily life.

This report concerns the development of a short, simple, non-invasive test for assessing sensitivity to irritant dermatitis. Application of NaOH (0.005-2.0 mol/l) to human skin resulted in significantly greater skin surface water loss directly after exposure (1-15 min) than of control (water). The increase in skin surface water loss after NaOH application was dose-dependent (0.005-0.1 mol/l) and application time-dependent (1-10 min). Application times exceeding 10 min did not further increase skin surface water loss and doses higher than 0.1 mol/l reversed the effect on skin surface water loss. 15 min after removal of the alkali, skin surface water loss baseline values were almost regained. This procedure did not cause visible reactions or discomfort for the volunteers. In a subsequent experiment, volunteers were exposed to 0.2 mol/l NaOH for 5 min on one forearm and to 1% sodium lauryl sulfate for 24 h contralaterally. Skin surface water loss after 5 min of NaOH application was significantly correlated with transepidermal water loss measurements after 24 h of sodium lauryl sulfate patch application. This is, to our knowledge, the first description of a procedure for quantifying interindividual differences in stratum corneum barrier function without inducing visible changes or causing volunteers discomfort. Use of this model should help to further investigate skin barrier function as well as to test protective devices and barrier creams.

Thirty patients without obvious skin disease but with subjective skin symptoms related to work with visual display units (VDUs) and 32 healthy persons were single-blind-tested with a solution of 5% lactic acid and pure water on their cheeks. Thirteen of the patients and 6 control persons reacted positively as "stingers" (p < 0.05) in this objective test of sensitive skin. The reason why some patients react with subjective symptoms like itching, burning, stinging, prickling or tingling is unclear. The result of this study, that patients with VDU-related skin symptoms have sensitive skin, does not tell anything about the aetiology of the symptoms. Former studies speak against the role of electric and magnetic fields and indicate that "techno-stress", cognitive factors or flickering from the VDUs or fluorescent tubes could be of importance, as could the Swedish mass media debate.

Irritation and staining, the side effects of dithranol and related compounds have previously been studied after a single chamber-exposure. To mimic the therapeutic situation, the chamber application was repeated for 3 weeks on the uninvolved back skin of 17 psoriasis patients. In equimolar concentrations corresponding to 0.05% dithranol, dithranol caused markedly more erythema and staining than 10-propionyl dithranol and 10-butyryl dithranol, whereas 10-butyryl dithranol irritated and stained less than 10-propionyl dithranol. To reach the irritation and staining level of dithranol, a 4-fold higher concentration of 10-butyryl dithranol was required. During the first week the irritation culminated, declining later despite repeated applications, possibly because of exhaustion of anthrone-induced inflammatory mediators.

Relatively mild exposure of human epidermis to sodium lauryl sulphate caused a general activation of the Langerhans cell system within 5 hours. An unexpected reactive phenomenon was that this irritant caused some cytomembrane parts to fold upon each other, thereby forming numerous Birbeck granules, several of which had an irregular shape. Spotty cytomembrane damage to the Langerhans cells was also observed.

In order to ascertain the extent to which the pigmentary system plays a protective role in dithranol-induced irritancy, a within-subject comparison was carried out between normally pigmented and depigmented skin of patients with vitiligo. In open patch tests, various concentrations of dithranol in a cream base were applied to the normally pigmented and depigmented skin of 6 patients with vitiligo. The responses were assessed 48 h after application. A mild to moderate inflammation occurred in the pigmented and depigmented skin and no statistically significant difference was shown between the two test areas. The present study does not support the hypothesis that the pigmentary system might be involved in dithranol-induced irritancy.

Thirty outpatients with limited (under 15% of skin area affected), symmetrical psoriasis of the plaque type were included in an open, right-left comparison study. Paraffin-based, 3% dithranol sticks (Ditrastick, Orion Pharmaceutica, Espoo, Finland) and similar, equimolar 4% butantrone sticks were used. Antipsoriatic activity, staining of the skin and clothes and irritation were the parameters followed up. An overall evaluation was made at the end of the trial. The antipsoriatic activity of dithranol and butantrone was almost equal at equimolar concentrations. Staining of the skin was significantly (at least p less than 0.05) milder with butantrone after 2 to 10 weeks treatment. Staining of clothes was less on the butantrone side for up to three months of use but was thereafter similar to that of dithranol. Irritation caused by butantrone reached its maximum only after 6 to 10 weeks and remained on average below the level of initial dithranol irritation. Six patients discontinued the treatment due to irritation by both preparations. Four patients tolerated better dithranol than butantrone. One patient could not use dithranol but cleared with butantrone. Thus, even if butantrone has an antipsoriatic efficacy almost equal to that of dithranol and is less staining than dithranol, it causes in some patients slowly increasing irritation with Koebner-like deterioration of the disease after some weeks of uneventful overnight use.

A short term anthralin application schedule was used at home in 42 patients with severe psoriasis. In another group of 21 patients treated at our day care center, UV-B irradiation was added when the surplus of anthralin had been washed off. Good healing results within 3-8 weeks were noted in most patients. To prevent relapses 31 patients continued the anthralin treatment once or twice a week after healing. In 15 cases this was combined with UV irradiation. One patient relapsed after a severe infection, but 16 others were observed for 6-9 months and 14 for 3-5 months without relapses. Irritation of non-affected skin is common especially at the beginning of the treatment and some staining of clothes and linen can occur. With proper information about this, the treatment is well accepted by the patient who generally finds it reasonably simple without the need of special protective dressings.

Mild dithranol irritation of healthy human skin has a stronger effect on the fine structure of Langerhans' cells (LC) than on that of other epidermal cells, causing mitochondrial enlargement and disruption of the cristae of LCs. With a stronger dithranol irritation, LCs were even more affected resulting in circular and branched Birbeck granules (BG) and blebbing of the LC cytomembrane. More often than is normal, BGs were contiguous with the LC cytomembrane. Electron microscopic observations indicated that blebbing and the abnormal BG formation were associated phenomena, in accordance with the hypothesis that BGs are endocytotic organelles formed from the cytomembrane.

The skin reactions to skin provocation tests with 11 primary irritants were compared in 21 pairs of men and women with hand eczema, matched for age, and in 21 pairs of non-eczematous subjects. With a few exceptions, no statistically significant differences were demonstrated in the intensities of the skin reactions between the sexes. The general skin reactivity in tests with irritants seems to be the same in men and women.

Ten psoriatics were tested with three concentrations of butantrone (0.66, 2.0 and 3.9%) on the healthy skin of the back and the irritant and staining reactions were compared with those produced by 0.1 and 0.5% dithranol, both in white petrolatum. Of the three test areas one was stripped before exposure to simulate the penetration of a psoriasis lesion, one after exposure to simulate posttreatment washing and one was unstripped. The contact times were 20 and 60 min. The degrees of erythema and staining, and the increase in skin blood flow were measured 1, 2, 3 and 7 days after application. Both dithranol concentrations produced a markedly stronger increase of blood flow and erythema than any of the butantrone concentrations and a clear dose response when the concentration was raised from 0.1 to 0.5%. Such a dose response was not clearly seen with butantrone. Staining with both dithranol and butantrone was minimal. Apparently, higher concentrations of butantrone than dithranol can be used in short contact therapy if cumulation of the drug can be excluded by a short contact time and careful removal of the surplus drug.