title: Assessment of the skin sensitization potency of eugenol and its dimers using a non-radioisotopic modification of the local lymph node assay.
abstract: Allergic contact dermatitis is a serious health problem. There is a need to identify and characterize skin sensitization hazards, particularly with respect to relative potency, so that accurate risk assessments can be developed. For these purposes the murine local lymph node assay (LLNA) was developed. Here, we have investigated further a modi fi cation of this assay, non-radioisotopic LLNA, which in place of tritiated thymidine to measure lymph node cell proliferation employs incorporation of 5-bromo-2'-deoxyuridine. Using this method we have examined the skin sensitizing activity of eugenol, a known human contact allergen, and its dimers 2,2'-dihydroxyl-3,3'-dimethoxy-5,5'-diallyl-biphenyl (DHEA) and 4,5'-diallyl-2'-hydroxy-2,3'-dimethoxy phenyl ether (DHEB). Activity in the guinea pig maximization test (GPMT) also measured. On the basis of GPMT assays, eugenol was classified as a mild skin sensitizer, DHEA as a weak skin sensitizer and DHEB as an extreme skin sensitizer. In the non-radioisotopic LLNA all chemicals were found to give positive responses insofar as each was able to provoke a stimulation index (SI) of >or=3 at one or more test concentrations. The relative skin sensitizing potency of these chemicals was evaluated in the non-radioisotopic LLNA by derivation of an ec(3) value (the concentration of chemical required to provoke an SI of 3). The ec(3) values calculated were 25.1% for eugenol, >30% for DHEA and 2.3% for DHEB. Collectively these data suggest that assessments of relative potency deriving from non-radioisotopic LLNA responses correlate well with evaluations based on GPMT results. These investigations provide support for the proposal that the non-radioisotopic LLNA may serve as an effective alternative to the GPMT where there is a need to avoid the use of radioisotopes.
authors.affiliation: Chemicals Assessment Center, Chemicals Evaluation and Research Institute, 3-822, Ishii-machi, Hita-shi, Oita 8770061, Japan. takeyoshi-masahiro@ceri.jp
authors.forename: Masahiro
authors.initials: M
authors.lastname: Takeyoshi
authors.forename: Shuji
authors.initials: S
authors.lastname: Noda
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Yamazaki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kakishima
authors.forename: Kanji
authors.initials: K
authors.lastname: Yamasaki
authors.forename: Ian
authors.initials: I
authors.lastname: Kimber
mesh_terms: D000485:Allergens / Q000633:toxicity*; D000818:Animals; D001713:Biphenyl Compounds / Q000633:toxicity*; D001973:Bromodeoxyuridine / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D017449:Dermatitis, Allergic Contact / Q000209:etiology / Q000378:metabolism / Q000473:pathology; D019281:Dimerization; D004306:Dose-Response Relationship, Immunologic; D005054:Eugenol / Q000031:analogs & derivatives / Q000633:toxicity*; D005260:Female; D006168:Guinea Pigs; D023441:Local Lymph Node Assay; D008198:Lymph Nodes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008808:Mice, Inbred CBA; D010647:Phenyl Ethers / Q000633:toxicity*; D015203:Reproducibility of Results; D012867:Skin / Q000187:drug effects* / Q000276:immunology
chemical_list: C490159:2,2'-dihydroxy-3,3'-dimethoxy-5,5'-diallylbiphenyl; C490160:4,5'-diallyl-1,2'-dihydroxy-2,3'-dimethoxyphenyl ether; D000485:Allergens; D001713:Biphenyl Compounds; D010647:Phenyl Ethers; D005054:Eugenol; D001973:Bromodeoxyuridine