Association of CD69 up-regulation on CD4+ Cla+ T cells versus patch test, strip patch test and clinical history in nickel sensitization.

OBJECTIVE: The patch test (PT) with its modification - the strip patch test (SPT) - is the standard in vivo procedure to diagnose an allergic contact dermatitis (ACD). To date, none of the in vitro tests for the diagnosis of ACD fulfils the requirements of an easy, valid and reliable test. To investigate the prediction ability of a flow cytometric assay of CD69 up-regulation on CD4+ CLA+ T cells in nickel-sensitive and non-nickel-sensitive patients. METHODS: In a prospective, investigator-blinded, clinical study a total of 85 nickel-sensitive (n = 44; 51.8%) and non-nickel-sensitive patients (n = 41; 48.2%) were enrolled. The association between CD69 up-regulation on CD4+ CLA+ T cells on the one hand and PT, SPT, and clinical history on the other hand was measured. Association is expressed with c statistic values (receiver operating characteristic analysis) and corresponding 95% CIs. RESULTS: The associations were c = 0.57 (95% CI: 0.42-0.72) between CD69 up-regulation and PT, c = 0.49 (95% CI: 0.36-0.62) between CD69 up-regulation and SPT, and c = 0.51 (95% CI: 0.37-0.64) between CD69 up-regulation and clinical history. CONCLUSIONS: CD69 up-regulation on CD4+ CLA+ T cells in vitro could not predict neither a positive PT or SPT result nor a positive clinical history to nickel sulfate. The combination of clinical history and patch testing still remains the basis for diagnosing ACD.

Standardized tape stripping: a practical and reproducible protocol to uniformly reduce the stratum corneum.

The basic idea of the strip patch test (SPT), a modification of the conventional patch test (PT), is to increase the bioavailability of a test substance in the deeper epidermal cell layers by defined tape stripping of the test area on the back prior to a PT. In a prospective, investigator-blinded clinical study, we evaluated the variability and the interrater agreement of our proposed SPT protocol. The relative stratum corneum (SC) reduction after tape stripping was measured on 75 subjects for variability and in a subgroup of 18 subjects for interrater agreement, by performing in vivo confocal laser scanning microscopy. We found good reproducibility with an SC reduction of 31%, with 95% of the values lying between 22 and 40%, and good interrater agreement. As a result, our SPT protocol yields a clinically adequate standardization of the SC reduction and the SPT may therefore be recommended for performance in daily clinical routine.

Strip patch test vs. conventional patch test: investigation of dose-dependent test sensitivities in nickel- and chromium-sensitive subjects.

BACKGROUND: Tape stripping the skin prior to patch testing (strip patch test, SPT) may enhance percutaneous penetration of test substances and increase skin reactivity to test substances. OBJECTIVE: To evaluate the test sensitivity of SPT in compliance with our recently presented practical method vs. conventional patch test (PT) in nickel- and dichromate-sensitive subjects. METHODS: Thirty subjects participated in the prospective, randomized, controlled, investigator-blind study. Serial dilution tests of nickel sulphate (10,000-50 ppm aq.) and potassium dichromate (1000-5 ppm aq.) were used. Tests were applied in duplicate to both sides of the upper back of the subject, where one, randomly chosen side was tape stripped. RESULTS: According to the estimated test sensitivities, SPT is more sensitive than PT in nickel- and dichromate-sensitive subjects, regardless of the interindividual different numbers of tape strips. The superiority of the SPT grows with diminishing concentrations of the allergens. CONCLUSION: Test sensitivity of SPT vs. PT is increased. If no positive results are obtained by PT, the SPT could help to detect hidden allergens in case of weak sensitization or low concentration and poor percutaneous penetration of the test substances.