title: Copper allergy revisited.
abstract: BACKGROUND
  Positive patch tests to copper sulfate are regularly observed, although copper is reported as a rare allergen with a low sensitizing potential. Usually they are claimed to be irritant and unspecific.
  
  
  OBJECTIVE
  The aim of this study was to assess the relevance and the diagnostic value of positive reactions to copper.
  
  
  METHODS
  A total of 2660 routine patch tests were analyzed for positive reactions to copper and other metal allergens: copper, 3.53%; nickel, 21.02%; palladium, 5.90%; cobalt, 3.31%.
  
  
  RESULTS
  Reactions to copper and nickel were highly significantly associated with each other. Twenty-six patients with a positive routine test to copper were retested. The reproducibility was modest (38%), but again significantly associated with nickel sensitization.
  
  
  CONCLUSIONS
  These clinical data support a copper-nickel cross-reactivity concept on T-cell level based on recently published molecular data. We conclude that positive patch tests to copper are mostly specific; however, they are usually of low clinical relevance.
authors.affiliation: FAZ-Floridsdorf Allergy Centre, Vienna, Austria.
authors.forename: S
authors.initials: S
authors.lastname: Wöhrl
authors.forename: W
authors.initials: W
authors.lastname: Hemmer
authors.forename: M
authors.initials: M
authors.lastname: Focke
authors.forename: M
authors.initials: M
authors.lastname: Götz
authors.forename: R
authors.initials: R
authors.lastname: Jarisch
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000485:Allergens; D003300:Copper / Q000009:adverse effects*; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D009532:Nickel / Q000009:adverse effects; D010328:Patch Tests; D015203:Reproducibility of Results
chemical_list: D000485:Allergens; D003300:Copper; D009532:Nickel