A skin-like cytochrome P450 cocktail activates prohaptens to contact allergenic metabolites

J Invest Dermatol. 2007 May;127(5):1145-53. doi: 10.1038/sj.jid.5700638. Epub 2006 Nov 23.


Allergic contact dermatitis is a complex syndrome representing immunological responses to cutaneous exposure to protein-reactive chemicals. Although many contact sensitizers directly can elicit this disorder, others (prohaptens) require activation. Knowledge regarding the activating mechanisms remains limited, but one possibility is metabolic activation by cytochrome P450 (CYP) enzymes in the skin. We have, after quantitative reverse transcriptase-PCR studies of the CYP content in 18 human skin samples, developed an enriched skin-like recombinant human (rh) CYP cocktail using CYP1A1, 1B1, 2B6, 2E1, and 3A5. To validate the rhCYP cocktail, a prohaptenic conjugated diene ((5R)-5-isopropenyl-2-methyl-1-methylene-2-cyclohexene) was investigated using: the skin-like rhCYP cocktail, a liver-like rhCYP cocktail, single rhCYP enzymes, liver microsomes, keratinocytes, and a dendritic cell (DC) assay. The diene was activated to sensitizing epoxides in all non-cell-based incubations including the skin-like rhCYP cocktail. An exocyclic epoxide metabolite ((7R)-7-isopropenyl-4-methyl-1-oxaspiro[2.5]oct-4-ene) was found to be mainly responsible for the allergenic activity of the diene. This epoxide also induced pronounced DC activation indicated by upregulation of IL-8. The skin-like rhCYP cocktail provides a simplified alternative to using skin tissue preparations in mechanistic studies of CYP-mediated skin metabolism of prohaptens and offers the future possibility of designing in vitro predictive assays for assessment of allergenic activity of prohaptens.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Allergens / immunology
  • Allergens / metabolism*
  • Animals
  • Biotransformation / physiology
  • Cells, Cultured
  • Cytochrome P-450 Enzyme System / physiology*
  • Dendritic Cells / cytology
  • Dendritic Cells / metabolism
  • Dermatitis, Allergic Contact / immunology
  • Dermatitis, Allergic Contact / metabolism*
  • Female
  • Haptens / immunology
  • Haptens / metabolism*
  • Humans
  • Interleukin-8 / genetics
  • Interleukin-8 / metabolism
  • Keratinocytes / cytology
  • Keratinocytes / metabolism
  • Male
  • Mice
  • Mice, Inbred Strains
  • Microsomes, Liver / enzymology
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Skin / enzymology*
  • Skin / immunology
  • Up-Regulation


  • Allergens
  • Haptens
  • Interleukin-8
  • RNA, Messenger
  • Cytochrome P-450 Enzyme System