title: Is p-tert-butylphenol-formaldehyde resin (PTBP-FR) in TRUE Test® (Mekos test) sensitizing the tested patients?
abstract: BACKGROUND
  In a population study using TRUE Test®, we noted late reactions to p-tert-butylphenol-formaldehyde resin (PTBP-FR) in 0.5% of subjects tested.
  
  
  OBJECTIVE
  In order to explore possible test sensitization, differences in the contents of sensitizers within PTBP-FR in test preparations for TRUE Test® and Finn Chambers® were analysed. Subjects allergic to PTBP-FR and subjects with late reactions to PTBP-FR were retested in order to explore whether these groups reacted to different PTBP-FR sensitizers.
  
  
  METHODS
  Four individuals with late reactions and 5 subjects with established allergy to PTBP-FR were retested with defined PTBP-FR sensitizers. PTBP-FR constituents in patches from TRUE Test® were analysed with high-performance liquid chromatography. Previously analysed samples of PTBP-FR constituents served as a reference.
  
  
  RESULTS
  The pattern of reaction to PTBP-FR sensitizers was similar in both groups. Subjects with suspected sensitization had somewhat stronger reactions than controls. The concentrations of monomers, dimers and trimers were generally higher in the TRUE Test® resin than in reference substances.
  
  
  CONCLUSIONS
  Retesting did not add information regarding causes of possible sensitization. Analysis showed that the resin used in TRUE Test® has a lower degree of polymerization or condensation, which may enhance its sensitizing properties. A follow-up of late reactions to PTBP-FR in TRUE Test® should be carried out.
authors.affiliation: Department of Public Health and Clinical Medicine, Dermatology and Venereology, Umeå University, 901 85, Umeå, Sweden.
authors.forename: Berndt
authors.initials: B
authors.lastname: Stenberg
authors.affiliation: Department of Occupational and Environmental Dermatology, Skåne University Hospital, Lund University, 214 28 Malmö, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Bruze
authors.affiliation: Department of Occupational and Environmental Dermatology, Skåne University Hospital, Lund University, 214 28 Malmö, Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Zimerson
mesh_terms: D000293:Adolescent; D000485:Allergens / Q000009:adverse effects*; D017449:Dermatitis, Allergic Contact / Q000209:etiology*; D005260:Female; D006801:Humans; D010328:Patch Tests / Q000379:methods*; D012117:Resins, Synthetic / Q000009:adverse effects*
chemical_list: D000485:Allergens; D012117:Resins, Synthetic; C014273:p-tert-butylphenolformaldehyde resin
keywords: active sensitization; late reactions; retesting