title: Reactivity to sodium tetrachloropalladate (Na2[PdCl4]) compared to PdCl2 and NiCl2 in lymphocyte proliferation tests.
abstract: BACKGROUND
  For patch testing, replacement of the commonly used palladium dichloride (PdCl2) by sodium tetrachloropalladate (Na2[PdCl4]) was recently demonstrated to improve test accuracy and show a significant correlation with nickel (Ni), supporting the concept of cross-reactivity between Pd and Ni. A promising alternative to metal allergy patch testing is the in vitro lymphocyte proliferation test (LTT).
  
  
  OBJECTIVE
  The aim of this study was to test whether Na2[PdCl4] is also more sensitive for diagnosing Pd allergy with a standardized LTT.
  
  
  METHODS
  After determining optimal nontoxic and nonmitogenic concentrations for Na2[PdCl4], blood samples from 105 patients with clinical suspicion of metal allergy were tested with an LTT called memory lymphocyte immuno stimulation assay for Na2[PdCl4], PdCl2 and NiCl2. Reaction profiles were analysed for concordant positive reactions.
  
  
  RESULTS
  Using the conventional cut-off of stimulation index > or = 3, 74.3% showed a positive reaction to NiCl2, 15.2% to PdCl2 and 28.6% to Na2[PdCl4]. All positive results to PdCl2 were covered by Na2[PdCl4]. From the 30 positive reactions to Na2[PdCl4], 26 (87%) were concordant for NiCl2 reactivity.
  
  
  CONCLUSIONS
  In LTT, the use of Na2[PdCl4] results in more positive reactions in Pd allergy testing which are in concordance with positive reactions to PdCl2 and NiCl2.
authors.affiliation: Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam, Louwesweg 1, Amsterdam 1066 EA, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Muris
authors.forename: C J
authors.initials: CJ
authors.lastname: Kleverlaan
authors.forename: A J
authors.initials: AJ
authors.lastname: Feilzer
authors.forename: E
authors.initials: E
authors.lastname: Valentine-Thon
mesh_terms: D000485:Allergens / Q000009:adverse effects*; D049109:Cell Proliferation; D003429:Cross Reactions; D006801:Humans; D006967:Hypersensitivity / Q000175:diagnosis* / Q000276:immunology; D007118:Immunoassay; D007156:Immunologic Memory; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000276:immunology; D009532:Nickel / Q000276:immunology; D010165:Palladium / Q000276:immunology*; D012680:Sensitivity and Specificity
chemical_list: D000485:Allergens; C030174:tetrachloropalladium; D010165:Palladium; C022838:nickel chloride; D009532:Nickel; C008756:palladium chloride