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

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Science Immunology  03 Jan 2020:
Vol. 5, Issue 43, eaax5430
DOI: 10.1126/sciimmunol.aax5430

Oily skin allergens hole up inside CD1a

Contact dermatitis induced by allergens in personal care products is a common cause of skin rashes, but the molecular mechanisms leading to T cell activation are poorly understood. Nicolai et al. tested known contact allergens for their ability to boost IFN-γ production by human T cells autoreactive to the CD1a antigen presentation molecule. Several hydrophobic chemicals came up as “hits,” including farnesol, a compound often used as a fragrance. Structural analysis of CD1a-farnesol complexes revealed that farnesol is buried deep within CD1a’s antigen-binding cleft beyond the reach of T cell receptor chains. These findings suggest that several hydrophobic contact allergens elicit T cell–mediated hypersensitivity reactions through displacement of self-lipids normally bound to CD1a, thereby exposing T cell–stimulatory surface regions of CD1a that are normally hidden.

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