Tracking Human Contact Allergens: From Mass Spectrometric Identification of Peptide-Bound Reactive Small Chemicals to Chemical-Specific Naive Human T-Cell Priming

• Published in: Toxicological sciences 2010-10, Vol.117 (2), p.336-347
• Main Authors: Dietz, Lisa, Esser, Philipp R., Schmucker, Sonja S., Goette, Irina, Richter, Anne, Schnölzer, Martina, Martin, Stefan F., Thierse, Hermann-Josef
• Format: Article
• Language: English
• Subjects: Allergens - chemistry; Allergens - metabolism; alternatives; Benzenesulfonates - chemistry; Benzenesulfonates - metabolism; Benzenesulfonates - toxicity; Cells, Cultured; contact allergen; Dendritic Cells - drug effects; Dendritic Cells - immunology; Dendritic Cells - metabolism; Dermatitis, Contact; Dinitrochlorobenzene - chemistry; Dinitrochlorobenzene - metabolism; Dinitrochlorobenzene - toxicity; haptenation; Humans; Lymphocyte Activation - drug effects; Lymphocyte Activation - immunology; mass spectrometry; Peptide Fragments - chemistry; skin sensitization; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; T cell; T-Lymphocytes - drug effects; T-Lymphocytes - immunology; T-Lymphocytes - metabolism
• ISSN: 1096-6080; 1096-0929
• DOI: 10.1093/toxsci/kfq209

Modification of proteins by reactive small chemicals is a key step in the activation of chemical-specific T cells in allergic contact dermatitis (ACD). However, an integrated approach to characterize both the precise nature of chemically modified proteins and the chemical-specific T cells is currently lacking. Here, we analyze the molecular conditions for adduct formation of the strong human contact sensitizer 2,4-dinitrochlorobenzene (DNCB) and its water-soluble form, 2,4-dinitrobenzenesulfonic acid (DNBS), with both an all amino acid–containing model peptide (± Cys) and the protein human serum albumin (HSA). Mass spectrometric detection and quantification revealed thiol-dependent peptide adduct formation at all pH values found in human skin layers. Highest modification rates were obtained with DNBS. Accordingly, DNBS- but not DNCB-modified human immature dendritic cells (iDC) induced in vitro primary human T-cell responses as did 2,4,6-trinitrobenzenesulfonic acid–modified iDC as measured by dinitrophenyl (DNP)- and trinitrophenyl (TNP)-specific T-cell proliferation and interferon gamma (IFN-γ) production in CD4+ and CD8+ T-cell subsets. Moreover, DNP-modified HSA protein effectively induced primary T-cell responses when processed by iDC. Thus, an integrated approach that combines efficient skin-related in chemico coupling analyses with an in vitro T-cell priming assay can be used to predict in vivo reactions of chemical contact allergens with extracellular and cellular proteins. This strategy supports the development of chemical-specific in vitro assays that are urgently required in predictive hazard identification and risk assessment of allergenic and nonallergenic chemicals.