Aeby P, Sieber T, Beck H, Gerberick GF, Goebel C. Skin sensitization to p-phenylenediamine: the diverging roles of oxidation and N-acetylation for dendritic cell activation and the immune response.
J Invest Dermatol 2008;
129:99-109. [PMID:
18704111 DOI:
10.1038/jid.2008.209]
[Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Skin is a target of allergic reactions to aromatic amine hair dye precursors, such as p-phenylenediamine (PPD). As conversion of PPD on or in the skin is expected to be required for the induction of allergic contact dermatitis, we analyzed the role of oxidation and N-acetylation as major transformation steps. PPD and its oxidative and N-acetylated derivatives were tested for their sensitizing potential in vitro using a dendritic cell (DC) activation assay and in vivo using the local lymph node assay (LLNA). PPD did not induce relevant DC activation but induced a positive LLNA response. In contrast, DC activation was obtained when PPD was chemically pre-oxidized or after air oxygen exposure. Under both conditions, the potent sensitizing PPD oxidation product Bandrowski's base was identified along with other di- and trimeric species, indicating that PPD oxidation products provide an effective immune stimulation (danger signal). In contrast mono- and diacetylated PPD did not induce DC activation or a positive LLNA response. We conclude that dermal N-acetylation of PPD competes with the formation of oxidized PPD whereas skin exposure conditions allowing auto-oxidation, as in the LLNA, provide an effective danger signal necessary to induce skin sensitization to PPD.
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