Sodium tetrachloropalladate (Na2[PdCl4]) as an improved test salt for palladium allergy patch testing

Background:  In the last decades, palladium is widely used in dentistry. Allergic reactions to palladium are rarely diagnosed with patch testing, even when positive results would be expected. Palladium tends to cross-react with nickel, which should give rise to more positive reactions to palladium dichloride (standard test salt).
Objective:  The aim of the study was to test whether or not mono-nuclear sodium tetrachloropalladate (Na₂[PdCl₄]) in petrolatum is a better test salt for diagnosing palladium allergy. Positive reactions to the investigated test salt are compared not only with PdCl_2(aq.), but also to NiSO_4(aq.) and NiSO_4(pet.).
Patients/Methods:  Concentration series of Na₂[PdCl₄] were carried out. 164 consecutive patients were patch tested.
Results:  3% of Na₂[PdCl₄]_(pet.) was found to be the highest non-irritative concentration. The results show ( n  = 164) that Na₂[PdCl₄] covers all reactions to PdCl₂ (1.8%) and provokes more positive reactions (14%). From the 164 patients, 18.3% reacted positively to at least 1 of the nickel salts.
Conclusion:  The sensitivity of patch testing with Na₂[PdCl₄] is increased compared with the PdCl₂ salt. Therefore, it can be concluded that Na₂[PdCl₄] is to be a better test salt for diagnosing palladium allergy with patch testing.     

Pre-treatment of nickel test areas with sodium lauryl sulfate detects nickel sensitivity in subjects reacting negatively to routinely performed patch tests

A fair % of patients with a clinical history of nickel allergy show negative patch test results. To improve the response rate to NiSO₄ 5% pet, patch tests, a testing procedure utilizing pre-treatment of I he lest area by a 24-h application of sodium lauryl sulfate (SLS) was introduced 46 women with a clinical history of nickel sensitivity who exhibited negative reactions to nickel sulfate 5% pet, patch tests. were studied, Patients underwent d patch tests on adjacent sites on the volar surface of the forcarms. 4 patch tests were performed with a 72-h application of 40 mg nickel sulfate 5% pet. While I of these patch tests served as control. 3 test areas underwent 24-h pretreatment with 40 μl SLS. 1 with 0.1% and 2 with 0.5% solution. To evaluate differences in the reactivity to SLS plus nickel sulfate related to the site on the forearm, 0.5% SLS pre-treatment was performed both on a proximal and on a distal lest site. At the 72-h evaluation. 19 subjects out of 46 showed positive reaction to nickel sulfate 5%. At skin sites pre-t railed with SLS. Whereas 23 patients reacted positively at 0.5% SLS pre-treated ureas. Echographic values of skin thickness and of hypo-echogeme dermal areas al positive pre-treated nickel lest. Next higher than al control Jest areas, confirming the clinical evidence of an increased response to NiSO₄ after SLS pre-treatment. The inflammatory reaction, is evaluated clinically and echographically, was much higher al distal skin areas (0.l% SLS and distal (0.5%.) SLS than at proximal 0.5% SLS ones.     

Patch test results with serial dilutions of nickel sulfate (with and without detergent), palladium chloride, and nickel and palladium metal plates

Clinical experience suggests the existence of different degrees of sensitivity in nickel-allergic patients. For quantification of this phenomenon, 462 consecutive patients with previously diagnosed or strongly suspected nickel allergy were tested with serial dilution patch tests with 5 ppm to 5% nickel sulfate in pet. (Ni), and 5 ppm to 1% nickel sulfate in pet. with 1% detergent (Ni/D). Additionally, nickel and palladium metal plates were tested in 103, and cobalt salts, dichromate and palladium chloride (PdCl₂) in most patients. 332 patients reacted positively to Ni or Ni/D. The influence of a concomitantly administered detergent was not significant. A significant correlation was found between positive reactions to low concentrations of Ni (or Ni/D), i.e., 0.1% or less ( N =166), and concomitant reactions to nickel metal plates, cobalt salts and PdCl₂ and a history of ear piercing with metal intolerance. The clinical relevance of reactions to PdCl₂ is at present not clear. A subgroup of nickel-allergic patients with "high sensitivity" can be defined. In future studies further addressing the clinical relevance of high versus low sensitivity, patch testing with 0.01, 0.1, 1.0 and 5% nickel sulfate in pet is recommended instead of routine tests with 5% only.     

Pretreatment of the test area with 1-day occlusion improves the response rate to NiSO4 5% pet. Patch tests in subjects with a positive history of nickel allergy

A group of 58 women, aged 18 to 51 years, with a clinical history of nickel allergy, who exhibited equivocal or negative reactions to nickel sulfate 5% pet, patch tests performed on the skin of the back, were recruited consecutively from the patch test clinic from September 1993 to June 19944. In order to improve the response rate to NiSO₄ 5% pet, patch tests, a testing procedure utilizing pretreatment of the test area by 1-day (24-h) occlusion was introduced. Patients underwent 2 patch tests on adjacent sites of the volar surface of both forearms. 3 of the patch tests were performed with 40 mg nickel sulfate 5% pet., whereas a control test was carried out by occluding with an empty chamber. 2 of the nickel sulfate test sites were pretreated with 1-day occlusion performed with an empty chamber. A visual grading system and echographic measurement were used to quantify the responses 30–40 min after patch test removal. Echographic evaluations were carried out using a 20 MHz B-scanner. Measurement of skin thickness and determination of the hypoechogenic dermal area, both considered to be parameters of inflammation, were used to evaluate the intensity of the allergic reaction. At the 3-day (72-h) evaluation. 19 subjects out of 58 clearly showed positive reactions to nickel sulfate 5% pet, at pre-occluded skin sites. Moreover, values of skin thickness and of 0–30 areas at positive pre-occluded nickel test areas were higher in respect to control test areas, confirming clinical evidence of increased response to NiSO₄, after occlusion.     

Open, closed and intradermal testing in nickel allergy

Open, closed and intradermal testing with NiCl₂ was performed in 15 subjects with patch-test-proven allergy to 5% NiSO₄ in pet. Intradermal testing proved to be a reliable method in confirming nickel sensitivity within 24 h. Open testing with non-toxic concentrations of NiCl₂ in alcohol resulted in 73% and 93% positive reactions at 24 h and 48 h readings, respectively. This test method can be used as a reliable screening method in nickel allergy. Open testing often resulted in positive reactions within a few hours. This makes it possible to investigate pathogenetic events of acquired allergic contact dermatitis at a much earlier stage than with the usual 48-h occlusion. 24-h occlusion with Finn Chambers is not sufficient if one is to avoid false negative reactions in nickel allergy. Occlusion with Finn Chambers seems to delay the reaction.     

Linalool – a significant contact sensitizer after air exposure

Background: Linalool is a widely used fragrance terpene. Pure linalool is not allergenic or a very weak allergen, but autoxidizes on air exposure and the oxidation products can cause contact allergy. Oxidized (ox.) linalool has previously been patch tested at a concentration of 2.0% in petrolatum (pet.) in 1511 patients, and 1.3% positive patch test reactions were observed.
Objective: To investigate the optimal patch test concentration for detection of contact allergy to ox. linalool.
Methods: Four concentrations of ox. linalool (2.0%, 4.0%, 6.0%, 11.0% pet.) were tested in 3418 consecutive dermatitis patients.
Results: Ox. linalool 2.0%, 4.0%, 6.0%, and 11.0% pet. detected positive patch test reactions in 0.83%, 3.2%, 5.3%, and 7.2% of the tested patients, respectively. The doubtful reactions increased with rising concentrations but relatively less, giving 5.1%, 6.4%, and 7.3% doubtful reactions, respectively, for ox. linalool 4.0%, 6.0%, and 11.0% pet. Few irritative reactions were seen.
Conclusions: Raising the patch test concentration for ox. linalool gave a better detection of contact allergy, as many as 5–7% positive patch test reactions were detected. We suggest a patch test concentration of ox. linalool 6.0% pet. for future patch testing, giving a dose per unit area of 2.4 mg/cm² when 20 mg test substance is tested in small Finn Chambers^®.     

Adverse skin reactions to vitamin K1: report of 2 cases

Vitamin K is essential to the biosynthesis of prothrombin and other clotting factors (VII, IX and X), and is mostly used for the prophylaxis of bleeding disorders, mainly in patients with hepatic disfunction (1). 4 different pharmacological forms exist: the natural form K1 (phytomenadione); K₂ (menaquinone), which is derived from intestinal bacterial action; K₃ (menadione); and K₄ (menadiol). The latter 2 are synthetic products. In Italy, only vitamin K1 is marketed (2).
Adverse cutaneous reactions to vitamin K are rare; 2 are mainly reported: an erythematous plaque (3, 4) or pseudo-scleroderma (5) at the injection site. Contact dermatitis and localized urticarial lesions have also been described (2).     

Patch test sensitization caused by para-tertiary-butylcatechol:

Para-tertiary-butylcatechol (PTBC) has been patch tested in Europe at 1% in petrolatum (pet.) and is now suspected of induction of patch test sensitization. A prospective study was initiated to obtain detailed data on this undesirable risk. A dilution series of PTBC (1%, 0.5%, 0.25%, 0.1% pet.) was used. Patch tests were read on days (D) 1-3, 7, 14 and 21 after application. Patients who were unable to return for late readings were telephoned and asked to report any reaction at the patch test sites. 40 out of 46 patients included completed the study. Patch tests were negative in 35 patients. 4 patients showed a positive patch test at later readings only (D7-D21); 2 patients reacted to a concentration as low as 0.1%. Rechallenge was performed in 2 of these patients, revealing a clearly positive reaction as early as D2 after patch test application. PTBC clearly induced patch test sensitization in 10% of the patients. It cannot be excluded that patch testing with 0.25% PTBC or with even lower concentrations might induce patch test sensitization. The optimal patch test concentration still has to be determined but may be within the range of 0.01% to 0.25% PTBC.     

A case of contact dermatitis due to impurities of cetyl alcohol

A 29-year-old man being treated for itchy lesions on the amputation stump of the thigh became allergic to betamethasone valerate and gentamicin sulfate cream (Rinderon VG®. Closed patch tests with all the ingredients of the cream revealed positive reactions to cetyl alcohol 30% to 5% pet. Gas chromatographic analysis of the cetyl alcohol in the cream base detected stearyl alcohol (C₁₈), myristyl alcohol (C₁₄) and lauryl alcohol (C₁₂) in addition to the main component of cetyl alcohol (C₁₆). Patch testing with 99% pure analytical reagent grade saturated alcohols. (C₁₀, C₁₁, C₁₂, C₁₃, C₁₄, C₁₅, C₁₆, C₁₇, C₁₈, C₁₉, C₂₀) showed negative reactions. Thus, it is concluded that some minor impurities in cetyl alcohol not detected by gas chromatography might be the cause of this dermatitis.     

Euxyl K 400: incidence of sensitization, patch test concentration and vehicle

The aim of this study was to verily the most suitable vehicle and concentration for testing Euxyl K 400 and its individual ingredients, and to evaluate the prevalence of sensitization to this preservative over the years in Italy. From January 1991 to October 1994. Euxyl K 400 2.5% pet, was positive in 99 patients (35 male. 64 female) out of 3455 (2.8%.). Of these, 22 out of 855 patients had a positive reaction during 1991 (2.6%), 29 out of 1037 in 1992 (2.8%), 28 out of 858 in 1993 (3.3%), and 20 out of 705 in 1994 (2.8%). 51 of the 99 patients with a reaction to Euxyl K 400 2.5% pet, showed a positive reaction to dibromodicyanobutane 0.5% pet, and 2 to phenoxyethanol 5% pet. The results of patch testing with serial dilutions of Euxyl K 400 in different vehicles indicate that water is a good vehicle for testing the preservative. However, since Euxyl K 400 is only hydrosoluble to a limited extent, the maximum concentration that can be tested using water is 0.5% and so with this concentration about 40% of sensitized patients are missed. The results of patch testing with serial dilutions of Euxyl K 400 in petrolatum demonstrate that concentrations lower than 2.5% are not suitable for detection of all sensitized patients. Euxyl K 400 in ethanol frequently causes irritant reactions without offering significant advantages in detecting sensitized patients.     

Allergic contact dermatitis from iodine preparations: a conundrum

Iodine preparations are widely used antiseptics, yet limited information exists on their irritant potential and threshold for diagnostic patch testing. We examine this issue by using iodine in different preparations and concentrations. A total of 24 fair-skinned, healthy volunteers without a history of iodine allergy, ranging in age from 18 to 65 years (mean age 49.5 + 10.7 SD), were recruited. Concentrations of 0.5%, 1%, 5% and 10% iodine in petrolatum (pet.), 0.5%, 0.75% and 1% iodine in 70% isopropyl alcohol (IPA) and 1%, 5%, 7.5% and 10% of povidone-iodine (PVP-I) were applied for 2 days to the intrascapular area on the back or to the volar forearm between cubital fossa and wrist using Finn Chambers on Scanpor. Test sites were read 2 days (D2) and 4 days (D4) after patch application. Skin reactions were graded according to the following scheme: 0 = no reaction, + = questionable erythema, 1 = definite erythema, 2 = erythema and induration and 3 = vesiculation. Mild-to-moderate reactions (+ to 2) were observed in 75% of the subjects patched with 5% iodine in pet. at 2-4 days after application. Almost all subjects reacted to 10% iodine at D2 and D4, with 65% exhibiting erythema and induration or vesiculation. A large number (33%) of the subjects developed some reactions to the low concentration (0.5%) of iodine in 70% IPA at D2. Vesicles were seen in 54% of the subjects patched with 1% iodine in 70% IPA at D4. Only 1 subject reacted to 7.5% and 10% PVP-I. Iodine can be irritant to normal skin in pet. and in 70% IPA. Pet. possibly enhances skin contact with iodine, thus increasing its irritant capacity. Alcohol removes sebum from the skin surface, and it might increase iodine penetration into the skin, causing a higher degree of irritation. PVP-I is relatively non-irritant, because its iodine is complexed in an iodophor. For diagnostic patch testing, we recommend using iodine at less than 1% in pet. and at less than 0.5% in 70% IPA. For PVP-I, 10% appears non-irritant. With the variation in patch-test irritant response, interpretation of the patch-test response in the light of clinical history is mandatory.     

Sensitization to patch test acrylates

Data on allergic contact dermatitis from acrylates and 4 patients sensitized during routine patch testing are reported. During 1982-1985, we used 7 different acrylates for tests. 1 patient out of 22 (= 4.5%) was sensitized to ethyl acrylate and butyl acrylate (1% pet.). Since September 1985, we have used a commercial (meth)acrylate series containing 28 substances. 3 of 24 patients tested became sensitized to ethyl acrylate, 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate (0.5% pet.). Because active sensitization with acrylates can be very harmful, it may be necessary to use lower concentrations than recommended. Currently, we test ethyl acrylate, 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate at 0.167% pet.     

Elicitation thresholds for thiuram mix using petrolatum and ethanol/sweat as vehicles

An estimate of amounts of thiurams that may be released from rubber gloves into synthetic sweat, has previously been generated. These amounts should be compared to elicitation thresholds Of patch tests performed with serial dilutions of thiuram mix using synthetic sweat as vehicle. Because of solubility properties of thiurams in aqueous media, such dilutions cannot directly be prepared. In this study, a stem solution was prepared in ethanol. This solution was then further diluted with synthetic sweat. Thiuram mix 0.5 w/v% was the most concentrated solution in ethanol achievable. The parch test reactions were compared to reactions to serial dilutions using petrolatum as vehicle. The experiment revealed that endpoint dilution with synthetic sweat was not achieved in this study. The threshold for elicitation of positive patch test reactions seemed to be lower for ethanol/sweat a, vehicle compared to petrolatum: 32% reacted to ethanol/synthetic sweat 0.001 mg/cm₂ compared to 14% reading to thiuram in pet. 0.0Q2 mg/cm₂. Based on these results, synthetic sweat may be considered a more relevant medium for threshold finding studies than petrolatum. Because of expected instability of the aqueous solutions, petrolatum is probably a more suitable vehicle for routine testing. The study does not permit final conclusions concerning acceptable thresholds for reachable thiurams in rubber gloves, but it is likely that an acceptable threshold would be substantially less than 0001 mg/cm₂.     

Late reactions to patch test preparations with reduced concentrations of p-phenylenediamine: a multicentre investigation of the German Contact Dermatitis Research Group

Background. p‐Phenylenediamine (PPD) 1% in petrolatum has been shown in a prospective study to elicit late reactions in 1.5% of routine patch tests, which may be indicative of patch test sensitization. Objectives. To assess the frequency of late reactions to reduced PPD patch test concentrations. Methods. In 1838 patients, PPD was tested at three concentrations (0.5% pet., group I; 0.4% pet., group II; and 0.35% pet., group III). Patch tests were read on D1 (D2) to D3 (D4); additional late readings were performed on D7, D14, and D21. Patients who were not able to return for all scheduled late readings were telephoned on D7, D14, and D21, and questioned about a reaction at the patch test sites. Results. Data of 1666 patients (1069 women and 597 men) were eligible. Late reactions were observed in 9 patients, 3 in group I (0.49%) and 5 in group II (0.63%). In 7 of 8 of the patients with late reactions, patch tests were applied for 48 hr. On retesting, 4 of 5 patients became positive at D2 or D3. Conclusions. The occurrence of late reactions to PPD may be influenced by patch test concentration and duration. PPD 0.4–0.5% pet. may cause late reactions indicative of active sensitization.     

Allergic contact dermatitis and mercury exanthem due to mercury chloride in plastic boots

We report a 5-year-old child with previous skin intolerance from Mercurochrome (merbromin). who developed a severe allergic contact dermatitis of both feet when wearing new polyvinyl chloride (PVC) boots. Within a few days, he developed a mercury exanthem involving both legs, groins and lateral parts of the trunk. Patch tests showed strong reactions to organic and inorganic mercury compounds, in particular to mercury chloride (mercuric chloride: HgCl₂), 0.01% pet., which was identified by atomic absorption spectrometry and polarography in the boots worn. New hidden sources of mercury in consumer goods may represent a potential source of danger for the future, if its use is not more strictly regulated.     

Prostanoid receptors in anagen human hair follicles

Abstract:  Prostanoid pathway in hair follicle gained closer attention since trichogenic side-effects on hair growth has been observed concomitantly with prostaglandin F_2α receptor (FP) agonist treatment of intraocular pressure. We thus investigated prostanoid receptor distribution in anagen hair follicle and different cell types from hair and skin. Using RT-PCR, Western blot and immunohistochemistry (IHC), we found that all receptors were present in hair follicle. This data shed new light on an underestimated complex network involved in hair growth control. Indeed most of these receptors showed a wide spectrum of expression in cultured cells and the whole hair follicle. Using IHC, we observed that expression of prostaglandin E₂ receptors (EP₂, EP₃, EP₄), prostaglandin D₂ receptor (DP₂), prostanoid thromboxane A₂ receptor (TP) and to a lesser extent EP₁ involved several hair follicle compartments. On the opposite, Prostaglandin I₂ receptor (IP) and DP₁ were more specifically expressed in hair cuticle layer and outer root sheath (ORS) basal layer, respectively. FP expression was essentially restricted to ORS companion layer and dermal papilla ( DP ). Although extracting a clear functional significance from this intricate network remains open challenge, FP labelling, i.e. could explain the biological effect of PGF_{2 α} on hair regrowth, by directly modulating DP function.     

Contact sensitization to N-(cyclohexylthio)phthalimide

Previous reports revealed relative high sensitization rates to the rubber chemical N-(cyclohexylthio)phthalimide (CTP; CAS-No. 17796-82-6), but the relevance of positive reactions remained unknown. It was discussed whether the test concentration of 1% pet. needed to be changed. The German Contact Dermatitis Research Group (DKG) added CTP in 3 concentrations, i.e. 0.25% pet., 0.5% pet, 1% pet., to the rubber series. From June 1999 to December 2000, 1936 patients in 30 departments of dermatology were tested with CTP. Of the 56 patients with a positive test reaction (2.9%), 52 reacted to CTP 1% pet., 21 to CTP 0.5% pet., and 9 to CTP 0.25% pet. The reaction indices were about the same with all concentrations. 34 patients with a positive reaction to CTP 1% pet. did not react to the lower concentrations. The majority of these reactions are probably false-positive. With CTP 0.25% pet., however, the majority of true allergic reactions to CTP were missed. Analysis of population characteristics and concomitant sensitizations to other rubber chemicals led to the conclusion that a positive reaction to CTP 0.5% pet. was a good indicator of contact allergy to CTP. Thus, the DKG decided to continue patch testing with CTP 0.5% pet. in the rubber series. Manufacturers' information about the use of CTP seem to partly contradict the patients' characteristics seen in this study. So the relevance of positive CTP patch test reactions, and the causative exposures in patients with CTP allergy, still remain to be clarified.     

Enhanced synthesis of cysteinyl leukotrienes in atopic dermatitis

Synthesis of cysteinyl leukotrienes was assessed in patients with atopic dermatitis (AD; n =8) and healthy volunteers ( n =8) by measuring urinary excretion of leukotriene E₄ (LTE₄), the main index metabolite of cysteinyl leukotrienes in man.
Using this non-invasive method we demonstrated a significant ( P <0.05) 4.5-fold increase in excretion of LTE₄ compared with healthy volunteers. The identity of LTE₄ was unequivocally demonstrated by gas chromatography-mass spectrometry/mass spectrometry (GC-MS/MS). LTE₄ was routinely measured by radioimmunoassay (RIA), and quantitative measurement of LTE₄ by RIA was validated by GC-MS/MS. There was a linear correlation between LTE₄ measured by RIA and by GC-MS/MS (r=0.994). Tn representative samples, LTE₄ was also quantitatively assessed by GC-MS/MS. In these samples, LTE₄ values obtained by GC-MS/MS differed <10% from those obtained by RIA. The present findings suggest that cysteinyl leukotrienes play a role in AD.     

Amount of nickel applied with a standard patch test

The concentration of nickel sulphate was determined in 9-16 mg test samples from commercially available patch test antigens. With two different manufacturers of 2.5% nickel sulphate in pet, the concentration range of 25 samples was 0.7 and 1.1% (+/- 2 SD) respectively, and with one manufacturer of 5.0% nickel sulphate in pet, the range was +/- 0.5%. In a normal patch test, the volume of patch test material applied with the Finn chamber technique should be 12-18 microliter (9-16 mg), but has been found to range between 9 and 50 microliter. Thus the amount of nickel applied in standard patch tests varies within at least 6-fold limits.     

Minimum eliciting patch test concentration of thimerosal

Positive patch test reactions to thimerosal 0.1% pet. (40/690 subjects: 5.8%) were more common in younger age groups, in the allergic contact dermatitis group and in subjects who had used contact lens solutions. In the 40 thimerosal-positive patients, the minimum eliciting quantity of preservative was evaluated using different test concentrations: 0.05% and 0.01% pet. (patch testing) and 1:10,000 in saline (intradermal testing). Cross-reactions between thimerosal and other mercury compounds and sensitivity to thiosalicylic acid were also examined. The results of the investigation demonstrate that many of the reactions to 0.1% thimerosal are probably irritant, because only half the subjects studied had positive patch tests when allergen concentrations 5 to 10x lower than that conventionally used for patch testing, were utilized. In these subjects, the average strength of patch test reactions was higher, intradermal testing was more often positive and cross-reactions between mercurials more frequent. These data indicate that the optimal eliciting patch test concentration for studying thimerosal sensitivity is 0.05% pet.