DOSE-RESPONSE TESTING WITH NICKEL SULFATE USING THE TRUE TEST(R) IN NICKEL-SENSITIVE INDIVIDUALS - MULTIPLE NICKEL SULFATE PATCH-TEST REACTIONS DO NOT CAUSE AN ANGRY BACK

The aim of this study was to employ the TRUE test(R) assay to confirm the presence or absence of the 'angry back' phenomenon, i.e. that a st rong positive patch-test reaction heightens adjacent patch-test respon se. In addition, we wished to establish the dose-response relationship for nickel sulphate patch tests among nickel-sensitive patients. Seve nty-two nickel-sensitive patients, 36 in Odense and 36 in Stockholm, w ere tested with a 10-step nickel sulphate dilution series (TRUE test(R )) and two placebo patches. The position of the patches was rotated, t o provide a balanced spatial distribution of the different concentrati ons. Readings were performed blind. The results were analysed by means of polynomial multiple-regression methods and a logistic dose-respons e model. Half the patients (38/72) had a threshold patch-test concentr ation for nickel sulphate in the range of 3-0.3 mug/cm2. The 'angry ba ck' phenomenon was not apparent in this study, as the spill-over effec t was not statistically significant. Strong reactions to high concentr ations of nickel sulphate did not enhance the response to adjacent low er concentrations of nickel sulphate.