Quantification of skin blood flow at patch test sites

Irritancy caused by the patch test procedure itself can be evaluated by measuring the skin blood flow with a laser Doppler flowmeter before application of the patches and at intervals after their removal. To investigate this technique further, van der Bend and True test patches with and without nickel sulfate were applied to the skin of the back and to the volar forearm in healthy subjects. Immediately after removal of the patches, the blood flow values in 26 of 32 test sites were higher than the corresponding pre-application values. In the majority of cases, blood flow had returned to pre-application values at 72 h (24 h after removal). This favours these patches compared to those used in previous studies (A1-test, Finn chambers, Silver patches), which caused a more lasting effect on skin blood flow. The common practice of relying mainly on the 72 h and 96 h readings of patch test sites was thus justified.

In vivo determination of cell mediated immune response in diabetic patients using a multiple intradermal antigen dispenser

The in vivo cell mediated immune response using a multiple intradermal antigen dispenser (Multitest) was evaluated in 99 diabetic patients (24 Type I and 75 Type II) and in 50 age matched normal subjects. Seven different antigens (tetanus, diphteria, streptococcus, tubercoline, candida, trichophyton, proteus and a glycerine control) were applied in the forearm and the induration for the antigens tested was measured 48 hours later. A score was calculated adding the arithmetic means obtained with each single antigen. Overall we did not find major differences between diabetic patients and controls except Type I patients of shorter duration (less than 5 years) having a reduced response (p less than 0.05) and both Type I and Type II patients showing an elevated response to candida antigen (p less than 0.001). No correlation was found between the intradermal response and metabolic control. As the intradermal test is a model for delayed type of hypersensitivity, these data suggest that the in vivo lymphocyte to lymphocyte cooperation in patients with long standing diabetes is not impaired.

PA Patch--a new patch testing device. Preliminary report

The PA Patch, a new multiple-antigen, predispensed patch testing device, was compared to the Finn Chamber in subjects with previous positive patch tests. After pressing the PA Patch well, the PA Patch performed as well as the Finn Chamber in nine subjects tested.

The "edge effect" with patch test materials

A positive "edge effect", i.e., the accumulation on the skin of a chemical solution (such as fluorescein 0.01% in a 50/50 water-ethanol solution) at the periphery of the patch test sites has been demonstrated. It occurs with different test materials (Finn Chamber; Silver Patch Test; Patch Test Chamber). Practical implications are discussed: this observation could be important when discussing results of laboratory investigations. In clinical practice, it could explain the occurrence of "ring-shaped" positive allergic patch test reactions to chemicals used in solution, i.e., Kathon CG or hydrocortisone.

Suitable bases for patch testing in tropical countries

Patients suspected of having contact dermatitis due to topical medicaments were patch tested with various bases to evaluate the most suitable base for tropical countries. Plastibase and polyethylene glycol 400 produced the least positive reactions. Both were therefore found to be suitable bases, although polyethylene glycol had more positive results than plastibase.

Viral contamination of intradermal skin test syringes

Intradermal skin tests are often performed using a common syringe with multiple needles. Bacterial contamination of intradermal skin test syringes can occur as a result of apparent siphoning caused by needle changing. The bacterial contamination of the syringe can be prevented by flushing the contaminated needle prior to changing. In this study, two different needle changing techniques were examined using a polio virus contaminant. Viral contamination of the syringe was not prevented by flushing the infected needle prior to removal. All syringes were contaminated with virus regardless of needle changing technique. We, therefore, cannot recommend the continued use of a common syringe for intradermal skin tests between patients regardless of needle changing technique.

The allergen quick test: a simple allergy test to prove existing sensitization

We have developed a new method of allergy skin test. The main advantages of the allergen quick test (AQT) are its simple and rapid procedure and its usefulness in screening trials for everyday clinical practice. The equipment consists of a disposable test applicator which is pre-loaded with the allergen solution to be tested. The AQT was used on 3800 subjects in a screening trial, and has been performed by several ENT specialists in their clinical practices since 1979. Evaluation of the results obtained confirms that this developed method is safe, easy to use, and accurate.

Serial delayed cutaneous hypersensitivity skin testing with multiple recall antigens in healthy volunteers: booster effect study

Booster effects on delayed cutaneous hypersensitivity (DCH) responses have been demonstrated for various antigens when DCH is measured by the Mantoux technique. In the present study, we investigated this possibility when assessing DCH responses using the Multitest CMI multipuncture technique with simultaneous injections of seven test antigens and a control. The DCH responses were quantified for each antigen and for the overall DCH response expressed as a DCH score. In a group of healthy volunteers, DCH was repeatedly tested either 1 month apart or 2 months apart at least six times. When volunteers remained healthy, DCH variations were observed with only two of seven tested antigens: streptococcus which slowly decreased (P = .012) and proteus which slowly increased (P = .04). Responses to the other antigens and the DCH score remained stable. In contrast, greater DCH variations were observed when infections occurred. The results with the Multitest CMI multipuncture show that repeated application had minimal booster effect on DCH responses and may be used to evaluate and follow immunocompetence of patients.

Standardization of the prick test. A comparative study of three methods

The different needles and methods used in the prick test give rise to disparate results. This has significance when carrying out multi-centre studies and when using the technique in the standardization of allergenic extracts. With test reliability as our objective, prick tests were carried out on 30 subjects: 10 patients sensitive to Dermatophagoides pteronyssinus received a glycerine extract of known allergenic potency, 10 healthy individuals 2.5% codeine phosphate in a glycerine solution, and another 10, histamine 1/1000. The total prick tests per individual was 27 with each of the needles employed (Allergy Pricker, the Morrow-Brown needle and Insulin needle in accordance with Pepy's procedure). The tests were carried out systematically by three different testers, and the total number of prick tests performed was 810. With the Allergy Pricker, no differences were observed among results obtained by the same tester, nor when the results of the three testers were compared. With the Morrow-Brown needle, the results varied in the same person and from one tester to another, and on many occasions the test was negative. With the Pepys method, no falsely negative results were obtained, but there was considerable variation in the size of the wheal. The variation coefficient is 41% with the Allergy Pricker, and 115% and 64% with the Morrow-Brown and Pepys method, respectively. In conclusion, the results obtained clearly indicate that the highest degree of reproducibility is obtained with the Allergy Pricker.

Cell-mediated immunity assessed by Multitest CMI skin testing in infants and preschool children

Two hundred twenty-one healthy children, from 6 months to 7 years of age, were tested for delayed-type hypersensitivity (DTH) by the Multitest CMI (cell-mediated immunity) (Merieux Institute, Miami). This device permits the simultaneous application of seven standardized recall antigens and a glycerol diluent control. Younger children were tested on the back and older children on the volar surface of the forearm. Only 6.8% of the children were anergic, and most of them (11/15) were female. The DTH responses were present for one or more antigens in 93% of the infants. The DTH responses increased tremendously during the second year of life and increased slowly thereafter. A relatively high incidence of positive reactions was found for three of the tested antigens--diphtheria toxoid (79%), tetanus toxoid (62%), and Proteus (57%), in children in the preschool years, and accounted for three fourths of all positive reactions. Much lower levels were found for Streptococcus (25%), Candida (16%), Trichophyton (5%), and tuberculin (4%). Measurement of DTH by the standardized Multitest CMI system seems to be a convenient and reliable tool for assessing CMI function in infants and small children. The tool permitted us to measure patterns of DTH responses from infancy onward in a healthy population and to develop index values in a normal reference population with which any tested preschool child can be compared.

The Finn chamber methylene blue ring

Metallic aluminium and methylene blue applied to human skin interact and give a strong resistant coloration, obtained neither with methylene blue itself nor with other dyes. The reaction proves that aluminium is not an inert material and that the aluminium in Finn chambers can be expected to interact with other patch test substances.

Delayed hypersensitivity responses of cancer patients to recall antigens using a new "Multitest" applicator

Testing of delayed-type hypersensitivity to recall antigens is acknowledged to be a useful assessment of cell-mediated immunity in cancer patients. The conventional method, however, has suffered from a lack of standardized antigens and variability owing to the method of application of the recall antigens. The Multitest-CMI system by the Merieux Institute offers an alterative. It employs standardized antigens and a single-stroke applicator, which is simpler to use and presumably subject to less variation. The present study compares the conventional and Multitest batteries done over an 8-month period in 403 cancer patients. The results suggest that the Multitest is easier to administer and is tolerated better by patients than the conventional method. Furthermore, the Multitest can detect recall antigen anergy or reactivity and correlates well in degrees of reactivity to the individual test battery. Consequently, Multitest-CMI can be substituted for the conventional battery in skin testing for immunocompetence in cancer patients.

An on-line ultraviolet radiation monitoring system for control of photosensitivity test dose

A system has been developed to monitor and integrate on-line a small fraction of the monochromatic ultraviolet radiation directed at the skin from a phototest source, thus correcting for fluctuations in the irradiance. On completion of the required test dose, the exposure is terminated automatically. Radiation is reflected from a silica plate, housed in a skin applicator, onto a photodiode connected to an integrator. The variation of the reflectivity of the silica plate with wavelength and with incident angle was calculated. The reflectivity of the applicator with and without the silica plate in situ was studied experimentally. Measurements were made of the spatial distribution of irradiance from and across the face of the applicator. To calibrate the photodiode current, the absolute irradiance at the face of the applicator had to be measured with a wide angle detector. No significant deviation from a linear variation was observed between changes in the skin irradiance and changes in the photodiode current.

Use of micrometers and calipers to measure various components of delayed-type hypersensitivity ear swelling reactions in mice

The choice of the type of instrument to measure delayed-type hypersensitivity (DTH) in mice, as assayed by ear swelling reactions, influences the experimental results. When a caliper that applies little pressure to the ears is employed, DTH reactions in ears of mice sensitized to picryl chloride show an early onset at 2 h after challenge, comparable swelling at 4 h and a slow rise to a 24 h classical peak response thereafter. In contrast, 3 different micrometers that apply more pressure to the ears reveal a biphasic pattern of ear swelling reactions in mice immunized and challenged with picryl chloride. The early component of DTH measured by these micrometers peaks 2 h after challenge. Thereafter the measured ear thickness declines, and the onset of the classical delayed reaction is detected at 12 h after ear challenge. Yet another instrument, that in contrast to the caliper and micrometers mentioned above, applies all the pressure to only a very restricted area of the ear, fails to detect an early swelling reaction; the delayed reaction is first detected at 12 h after ear challenge and rises thereafter to a 24 h peak. The differences in outcome of the assays using the different instruments indicate that the early component or DTH reactions differs from the late component of DTH reactions in that the early swelling is easier to compress when pressure is applied by the instrument used for measurement. This is probably caused by the fact that the late reactions are due to a cellular infiltrate, whereas the early reactions are edematous in character, and are due to accumulation of plasma components.

Multitest CMI for standardized measurement of delayed cutaneous hypersensitivity and cell-mediated immunity. Normal values and proposed scoring system for healthy adults in the U.S.A

The Multitest CMI system, a disposable device that simultaneously applies seven standardized preloaded antigens and diluent control, is a major advance for measurement of delayed type hypersensitivity (DTH) in assessment of cell-mediated immunity (CMI). The system was tested in 402 healthy adults, aged 17 to 92 years, to determine normal values for incidence and size of DTH responses. Incidence of positive responses to individual antigens varied from 85% to 46%, with great variability related to age and sex. To better assess CMI, a two-part score based on 48-hour readings was employed. The mean number of positive antigens ranged between four and five, and the mean sum of their mm induration ranged between 18 and 25, with both scores increasing with advancing age. A statistical zone of reduced DTH scores (hypoergy) was identified. The Multitest CMI system appears to be a practical means of reproducibly assessing CMI in subjects with immunologic, metabolic, infectious, or neoplastic disorders. The scores in our population may serve as reference values to which results from any tested adult can be compared.