[Prick tests using RM steel lancets]

There exist several technics of application for allergy skin tests: intradermal in which the antigen is injected in the dermis: mean while in the other puncture method (PRICK), the antigen is applied on the skin and it is introduced with a device in the epidermis which there exist several technics of application. Realizing an analysis of different methods it's known that in the patients in which are indicated to realize direct skin test, we should practice first the puncture test, which are easy to apply with less or a minimum systemic and local reactions. To facilitate its application and reduce costs, we suggest the modified method, in a tray Multiwell with antigen, where are put sterilized reusable steel lancets previous sterilization to realize the punctures. We analyze different costs in materials that are used so they would be of easy acquisition.

Comparison of two disposable plastic skin test devices with the bifurcated needle for epicutaneous allergy testing

BACKGROUND

The Greer DermaPIK and the Lincoln Diagnostics Duotip-Test are frequently used plastic, disposable, allergy skin testing devices.

OBJECTIVES

To compare the prick method of using the bifurcated needle and DermaPIK with the Duotip-Test using both the scratch (rotation) and prick methods for sensitivity, precision, and level of discomfort.

METHODS

Skin-testing was done with histamine and saline on the back in triplicate on 24 volunteers (mean age 32.8, seven males). Wheal and erythema were measured and a photograph was taken. Discomfort was rated on an analog scale.

RESULTS

The bifurcated needle and the Duotip-Test prick technique had significantly smaller histamine wheal and erythema responses than either the DermaPIK prick or Duotip-Test scratch techniques (P < .05). The Duotip-Test scratch produced significantly larger wheals (mean 1.1 mm, P < .001) to saline than the other three methods. Erythema to saline by Duotip-Test scratch (mean 3.16 mm) was significantly larger than the bifurcated needle (mean 1.2 mm, P < .001) and Duotip-Test prick method (mean 1.6 mm, P < .01). There was no statistical difference in the histamine coefficient of variation among the four methods. The Duotip-Test scratch method was rated significantly higher in patient discomfort (mean 21.6, P < .05) than the bifurcated needle (mean 7.8). No differences in discomfort were noted between the other methods.

CONCLUSIONS

The Duotip-Test scratch method had the largest mean wheal/erythema to histamine and the lowest CV. It had the most dermatographism and was more uncomfortable than the other methods. The other devices and methods were very similar in response to histamine and saline, and to precision and discomfort.

Sodium lauryl sulfate effect on the density of epidermal Langerhans cells. Evaluation of different test models

The effect of different test models for sodium lauryl sulfate (SLS)-induced irritant contact dermatitis on epidermal Langerhans cells (LC) numbers was examined. Finn Chambers, 8 and 12 mm, containing 15 and 34 or 50 microliters, respectively, of 1% aq. solution of SLS were applied to human forearm skin for 48 h as single or repeated application. The results showed a clear difference between the effects with the 2 chamber sizes. The effect of the 8-mm chambers could result in increased, unchanged or decreased LC numbers, while 12-mm chambers always produced a decrease. These results seem to explain, at least partly, the discrepant results reported from various laboratories.

[Comparative study of 3 types of lancets for performing prick tests]

Skin Prick Test is considered the cutaneous test of choice in rutinary clinical practice as well as in research. In the last 15 years a large number of lancets for puncture test have been developed looking for a higher level of standardisation and reproducibility. We have compared three lancets, two of them, NeoAbelló (NA) and Dome/Hollister Stier (DHS), used in puncture test and a third one, Blood Lancet (BL), in the modified prick test. Twenty-two patients sensitised to Phleum pratense were tested with the three lancets at three extract concentrations and histamine 10 mg/mL in duplicate. We compared their wheal sizes by means of parallel line assay, their reproducibility, frequency of bleeding wheals, the disturbance for the patient and the correlation between specific IgE and skin response. Wheal size was similar for puncture tests (DHS and NA lancets) and significatively lower than BL, being necessary to increase 1.9 times the extract concentration when using DHS and NA lancets to achieve the same wheal size than when using BL lancets (p < 0.01). Reproducibility with histamine was similar with the three lancets while with the extract was somehow better with puncture tests but without statistical significance. Bleeding was significantly more frequent with BL although this did not influence the results. Less pain was obtained with BL. Finally, correlation with specific IgE was slightly significant for NA and very similar for the other two. With these results in mind we think that any of the three lancets is valid for the diagnostic of the allergic patient. Nevertheless, puncture tests are probably the most suitable at a research level.

Sensitive skin and stratum corneum reactivity to household cleaning products

Products intended for individuals with sensitive skin are being increasingly developed by formulators of household cleaning products. However, there is currently no consensus about the definition and recognition of the biological basis of sensitive skin. We sought to determine the relation between the nature of environmental threat perceived as aggressive by panelists, and the stratum corneum reactivity to household cleaning products as measured by the corneosurfametry test. Results indicate substantial differences in irritancy potential between proprietary products. Corneosurfametry data show significant differences in stratum corneum reactivity between, on the one hand, individuals with either non-sensitive skin or skin sensitive to climate/fabrics, and, on the other hand, individuals with detergent-sensitive skin. It is concluded that sensitive skin is not one single condition. Sound information in rating detergent-sensitive skin may be gained by corneosurfametry.

Irritant effects of a detergent in wash, chamber and repeated open application tests

Development of irritant contact reactions in a wash test, in a repeated open application test (ROAT) and in chamber tests were compared with each other in 14 atopic and 14 non-atopic Caucasian medical students. In the wash test, the students washed their upper arm skin with 10% dishwashing liquid for 1 min 2 x a day for 1 week. In the ROAT, they applied the same detergent solution to 1 antecubital fossa 2 x daily for 1 week. Chamber tests were performed with the same detergent using 8 mm, 12 mm and 18 mm Finn Chambers applied to the upper back skin for 48 h. Additional 4 h and 24 h occlusion times were used with the 12 mm Finn Chambers. Test results were evaluated on days 0, 2, 4 and 7 by eye and by using an Evaporimeter EP1 for transepidermal water loss and a Minolta Chroma Meter CR-200 for skin colour. No statistically significant differences between atopics and non-atopics were found in any of the tests. The results of the tests did not correlate with each other, with the exception of the 12 mm/48 h chamber test and the wash test in atopics (R = 0.61, p = 0.02). It seems that other individual factors in addition to atopy influence the development of irritant contact dermatitis. The results of the chamber test and ROAT predicted poorly the result of the wash test.

Food-induced contact urticaria syndrome (CUS) in atopic dermatitis: reproducibility of repeated and duplicate testing with a skin provocation test, the skin application food test (SAFT)

IgE-mediated contact urticaria syndrome (CUS) is one of the manifestations of allergy in childhood atopic dermatitis (AD). Allergens such as foods and animal products penetrate the skin easily. They can then cause urticarial reactions in sensitized individuals. A provocation test system for foods, called the skin application food test (SAFT), has been developed. Over more than 5 years, a group of 175 patients with AD was built-up and investigated in a prospective follow-up study with SAFT. SAFT was more frequently positive in AD children aged 0-2 years than in older children. In several children of this population (Group 1), we repeated SAFT within a period of 1 year. In another unrelated group of children (Group 2-1), we compared the results of 'original' SAFT and SAFT using square chambers (Van der Bend) or Silver patches. In the 3rd group (Group 2-2) we compared 'original' SAFT with SAFT using big Finn Chambers. The agreement between the tests was high: in Group 1, we observed 88 to 93% concordant scores, and in Group 2, the scores were 96% to 100%. Statistically, the kappa coefficient ranged from 0.71-0.87 in Group 1, and from 0.83-1.00 in Group 2. SAFT is therefore highly reproducible. Agreement was at least > or = 88% between the scores (the lowest kappa value observed was at least 0.71).

Kiwi fruit allergy: a new birch pollen-associated food allergy

BACKGROUND

To determine the cross-reacting antigens of kiwi fruit and other foods and pollen, we investigated 22 patients allergic to kiwi fruit: 10 with severe systemic reactions and 12 with localized symptoms confined to oral and pharyngeal mucosa (oral allergy syndrome). Seven patients with birch pollen allergy who tolerated kiwi fruit were included as a control group.

METHODS

All patients were evaluated by skin testing and RAST; three patients were evaluated by RAST inhibition assays.

RESULTS

Prick tests showed positive reactions to kiwi fruit in all patients, whereas specific IgE to kiwi fruit could be demonstrated only in patients with generalized severe symptoms. Surprisingly, all 22 patients with clinical kiwi allergy showed positive prick test results and elevated IgE to birch pollen. Clinically, all complained of rhinitis during birch pollen season. Many patients showed sensitization to grass and mugwort pollen. Also, food allergy was found to be associated with kiwi allergy: we found strong reactions to apple and hazelnut; moderate reactions to carrot, potato, and avocado; and weak reactions to wheat and rye flour, pineapple and papaya, and their enzymes bromelain and papain. RAST inhibition studies revealed cross-reacting antigens between birch pollen and kiwi fruit. Interestingly, patients with birch pollen allergy without clinical signs of kiwi allergy had positive prick test reactions to kiwi. Patients with kiwi allergy showed higher concentrations to birch pollen IgE compared with patients with isolated birch pollen allergy.

CONCLUSIONS

Our results indicate that kiwi allergy is a new manifestation of birch pollen-associated food allergy and is mediated by cross-reacting antigens in the kiwi fruit. Kiwi allergy can be expected in patients with birch pollen allergy exhibiting high levels of IgE to birch pollen.

Quantitative determination of skin reactivity by two semiautomatic devices for skin prick test area measurements

For quantitative use of skin prick tests (SPTs), the circumference of the wheal and/or the flare is outlined by a pen, and transferred to a paper by adhesive tape. The biological response is considered proportional to this area. We have previously developed software, the SPT-scanner, for determination of SPT areas (5-500 mm2) by a hand-held scanner and a personal computer. This study is aimed at comparing the SPT-scanner with another semiautomated system, where the outline of the wheal is followed by a digitizer pen. Comparing 2080 SPT areas from a pharmacological study of cetirizine, the two systems correlated well (r = 0.980, p < 0.001), the digitizer generally giving larger areas than the SPT-scanner. Probably, the line is considered as a part of the wheal/flare in the digitizing system, whereas the scanner only detects areas within the circumference. In conclusion, the SPT scanner is objective and reproducible for rapid SPT area determination.

Comparative performance of five commercial prick skin test devices

Five commercially available devices for performing prick skin testing were compared for reproducibility, patient acceptance, occurrence of false-negative skin test results, and size distribution of reactions at the negative control sites. Reproducibility of skin testing with 10 mg/ml histamine base, as expressed by coefficient of variation, was similar. However, a clear range of trauma to the skin was produced by the devices. This trauma was least with the Hollister-Stier and ALK Laboratories lancets, intermediate for the bifurcated needle by either prick or puncture, and greatest for the Multi-Test and DermaPIK devices. The more traumatic devices produced larger mean wheals and more frequent and large reactions at saline control sites, and were less acceptable to subjects. However, except for the Multi-Test device, they less often yielded false-negative responses. It is proposed that for each device a different size of wheal must be produced at the allergen site to have confidence that it exceeds the control site. The wheal size necessary for 99% specificity were as follows: Hollister-Stier lancet, 2 mm; ALK lancet, 3.0 mm; bifurcated needle prick, 4.0 mm; bifurcated needle puncture, 4.5 mm; Multi-Test device, 5.0 mm; and DermaPIK device, 5.5 mm. An additional observation was the presence of a significant gradient of reaction size on the back to both histamine and allergen (p < 0.0001), with the smallest reactions in the upper third and the largest in the lower third of the back.

Introduction to in vivo allergy testing

Available in vivo skin tests for assessment of hyperreactivity are essentially similar in principle, in that they rely on the reactivity and sensitivity of dermal mast cells sensitized with specific immunoglobulin E to reflect allergic sensitivity. In this article the immunology of skin testing is examined and the various factors that may influence reactivity are noted. In addition, the respective benefits and drawbacks of such familiar epicutaneous skin tests as the scratch and prick tests and intradermal (or intracutaneous) methods, including skin end point titration, are explored. Efforts to standardize testing technology are also discussed. It is concluded that each method of in vivo skin testing is associated with both advantages and disadvantages and that the most important factors are sensitivity and reproducibility.

The batch-to-batch variation of the potency of dog- and cat-allergen-coated lancets. Evaluation by skin prick testing

In clinical work I formed the impression that the potency of Phazet lancets, for cat and dog allergens, was lower than earlier and too low to diagnose all clinically sensitive children with cat and dog allergy. Therefore, I decided to investigate the potency of newly produced and several years old Phazet lancets coated with dog and cat allergens. Twenty-six adults with case histories of cat and/or dog allergy and skin reactive to extracts of either dog dander or cat epithelium were skin prick tested in duplicate with one old batch and one newly produced batch of Phazet dog and/or cat lancets as well as the in-house reference of cat and/or dog allergen, 100,000 BU/ml. The potency of Phazet lancets in relation to the standard was evaluated by the median slope of the allergen dose-response relationship. The potency of the old dog lancets (mean 48,900 BU/ml) was higher (NS) than that of the newly produced lancets (mean 28,000 BU/ml), and the potency of both types of lancets was significantly less (P < 0.001) than that of the dog allergen in-house standard. On the other hand, the potency of newly produced (123,000 BU/ml), but not old (108,000), cat-allergen-coated Phazet lancets was higher than that of the cat allergen in-house reference extract (P = 0.048). There was a marked variation in potency between patients. Most of this variation was due to factors varying between patients, not between lancets, indicating that the composition of the allergen on the lancets was partly different from that of the standard.(ABSTRACT TRUNCATED AT 250 WORDS)

Validity and reproducibility of multi-test skin test device

Thirty patients were skin tested by Multi-Test and Morrow Brown needle using antigens, histamine, glycerosaline, and blank controls to examine reproducibility and influence of positive reactions on adjacent negative controls. There was no evidence that histamine or strongly positive antigen reactions affected adjacent negative controls. Multi-Test was more reproducible, and preferred by patients over Morrow Brown.

Evaluation of the Multi-Test device for immediate hypersensitivity skin testing

Test-to-test reproducibility, user variability, and the effect of positive reactions on adjacent negative sites were evaluated for the Multi-Test skin testing device. Twenty-five subjects had skin tests with 24 histamine (1 mg/ml), four glycerosaline controls, and four "dry" controls on two testings 7 days apart. To assess reproducibility from large and smaller histamine reactions and/or their effect on adjacent negative controls, 10 of the 25 subjects were retested once with the same testing format, but histamine at 10 mg/ml was substituted. To determine whether large allergen reactions affect adjacent negative controls differently than histamine reactions, 24 additional patients were retested on arms and back with negative controls adjacent to allergens to which they had prior 3+ to 4+ skin test reactions. Conclusions from 2688 skin tests on 49 patients are as follows: large (mean > 10 mm) histamine reactions reproduced better than smaller (mean < 7 mm) responses--coefficients of variation were 12.3 and 21.4 respectively. A 14% user variability occurred when comparing mean wheal sizes from histamine produced by each nurse and 1.2% when comparing their coefficients of variation. Neither small histamine reactions nor large reactions from histamine and allergens affected adjacent negative controls. We conclude that Multi-Test is a highly reliable skin testing technique that provides good reproducibility of results and low user variability.

Comparison of the sensitivity and precision of four skin test devices

Twenty volunteers were skin tested with seven concentrations of histamine phosphate and a glycerosaline control to determine the relative sensitivity and precision of four skin test devices: Greer Pen (GP), Greer DermaPIK (DP), Center Multi-Test (MT), and Morrow Brown needle (MB). The end points of the study were (1) wheal and flare response of each device, with a dose-response curve, (2) the time required to apply each set of eight tests, and (3) the volunteers' subjective assessment of each device. On a different day, 10 of the volunteers were tested to determine the precision of each device. Dose-response curves for half-log dilutions of histamine phosphate were produced with a glycerosaline control. The DP and GP induced wheal and flare responses discernible from that of the glycerosaline control at a lower concentration of histamine phosphate than the MB and MT. The DP took a shorter time to apply eight samples than any other device. The MB was preferred by the most volunteers, but any device tested on the upper half of the back was usually preferred over that tested on the lower half. When 5 mg/ml histamine phosphate was used, coefficients of variation for each device demonstrated that for wheals the precision of the DP, GP, and MT was similar (mean, 21.1%, 23.1%, and 24.5%, respectively). The MB was larger (mean, 59.9%). For flares, the precision of GP and DP was similar (mean, 22.0% and 23.5%, respectively), with the MT and MB larger (mean, 35.5% and 58.2%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Use of an electrocardiograph to record the skin-resistance response with a new type of electrode

A new method is described for recording the emotion-induced decrease in skin resistance area, which is known as the skin-resistance response (SRR). The method employs a simple current source and a new type of tetrapolar electrode in which the SRR is measured with the non-current-carrying electrodes. The signal produced can be recorded with a standard electrocardiograph. Typical SRRs from two subjects are presented.

Skin prick testing using allergen-coated lancets: a comparison between a multiple lancet device and a single lancet applied with varying pressures

Allergen-coated lancets have been developed to simplify skin prick testing. The effect of variation in application pressure on the response to prick tests was assessed in 20 atopic subjects, and the results compared to the response obtained with a newly devised multiple lancet device (MLD), capable of holding up to eight lancets and of providing a standardized application pressure. A positive weal (greater than or equal to 7 mm2) using light pressure occurred in 2/20 subjects, compared with 14/20 after moderate pressure. The largest weals were obtained using hard pressure and with the MLD (all 20 subjects obtained positive weals) and there was no significant difference in weal size between the two. There was evidence of a late reaction in 4/17 subjects with the MLD and with hard pressure applied to a single lancet, but in only one with moderate and in none with light pressure. Thus both the early and late skin responses are dependent on the pressure applied. The newly designed MLD allows skin prick tests to be performed using a standard pressure. It is also convenient for multiple allergen testing of uncooperative children.