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  • Human T cell response to CD1a and contact dermatitis allergens in botanical extracts and commercial skin care products.

Human T cell response to CD1a and contact dermatitis allergens in botanical extracts and commercial skin care products.

Science immunology (2020-01-05)
Sarah Nicolai, Marcin Wegrecki, Tan-Yun Cheng, Elvire A Bourgeois, Rachel N Cotton, Jacob A Mayfield, Gwennaëlle C Monnot, Jérôme Le Nours, Ildiko Van Rhijn, Jamie Rossjohn, D Branch Moody, Annemieke de Jong
ABSTRACT

During industrialization, humans have been exposed to increasing numbers of foreign chemicals. Failure of the immune system to tolerate drugs, cosmetics, and other skin products causes allergic contact dermatitis, a T cell-mediated disease with rising prevalence. Models of αβ T cell response emphasize T cell receptor (TCR) contact with peptide-MHC complexes, but this model cannot readily explain activation by most contact dermatitis allergens, which are nonpeptidic molecules. We tested whether CD1a, an abundant MHC I-like protein in human skin, mediates contact allergen recognition. Using CD1a-autoreactive human αβ T cell clones to screen clinically important allergens present in skin patch testing kits, we identified responses to balsam of Peru, a tree oil widely used in cosmetics and toothpaste. Additional purification identified benzyl benzoate and benzyl cinnamate as antigenic compounds within balsam of Peru. Screening of structurally related compounds revealed additional stimulants of CD1a-restricted T cells, including farnesol and coenzyme Q2. Certain general chemical features controlled response: small size, extreme hydrophobicity, and chemical constraint from rings and unsaturations. Unlike lipid antigens that protrude to form epitopes and contact TCRs, the small size of farnesol allows sequestration deeply within CD1a, where it displaces self-lipids and unmasks the CD1a surface. These studies identify molecular connections between CD1a and hypersensitivity to consumer products, defining a mechanism that could plausibly explain the many known T cell responses to oily substances.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Geranylgeranylacetone
Sigma-Aldrich
cis-11-Hexadecenal, 95%
Sigma-Aldrich
Benzyl cinnamate, 99%
Sigma-Aldrich
trans,trans-Farnesol, 96%
Sigma-Aldrich
1-Dodecyl-2-pyrrolidinone, 99%
Sigma-Aldrich
Vitamin K1, viscous liquid
Sigma-Aldrich
Oleamide, ≥99%
Sigma-Aldrich
Benzyl benzoate, meets USP testing specifications
Sigma-Aldrich
Palmitoleyl alcohol, ≥98% (capillary GC)
Sigma-Aldrich
Squalene, ≥98%, liquid
Sigma-Aldrich
Geranylgeraniol, ≥85% (GC)
Sigma-Aldrich
Vitamin K2
Sigma-Aldrich
Peru balsam
Sigma-Aldrich
Geraniol, 98%
Sigma-Aldrich
(±)-α-Tocopherol, synthetic, ≥96% (HPLC)
Sigma-Aldrich
Cholecalciferol, ≥98% (HPLC)
Sigma-Aldrich
Coenzyme Q1, ≥95%
Sigma-Aldrich
Palmitoylethanolamide
Sigma-Aldrich
Palmitoleic acid, ≥98.5% (GC), liquid
Sigma-Aldrich
2,3-Dimethoxy-5-methyl-p-benzoquinone, apoptosis inducer
Sigma-Aldrich
Methyl palmitoleate, ≥99% (capillary GC), liquid
Sigma-Aldrich
Retinol, synthetic, ≥95% (HPLC), (Powder or Powder with Lumps)
Sigma-Aldrich
Coenzyme Q10, ≥98% (HPLC)
Sigma-Aldrich
Coenzyme Q2, ≥90%