CD1a-autoreactive T cells recognize natural skin oils that function as headless antigens

Area of Science:

• Immunology
• Biochemistry
• Dermatology

Background:

• T cells autoreactive to CD1a are prevalent in human skin.
• Identifying natural autoantigens presented by CD1a is challenging due to background T cell responses.

Purpose of the Study:

• To identify natural autoantigens presented by CD1a in human skin.
• To elucidate the mechanism by which CD1a presents autoantigens to T cells.

Main Methods:

• CD1a-lipid complexes were captured and ligands were gently eluted.
• Preserved CD1a was used to test eluted lipids from human tissues.
• Ligand types and structures were analyzed to identify autoantigens.

Main Results:

• CD1a presented hundreds of ligands, categorized as inhibitory (ubiquitous membrane lipids) and stimulatory (apolar oils).
• Squalene and wax esters, found in epidermis and sebum, were identified as CD1a-presented autoantigens.
• T cell activation by skin oils suggests a mechanism involving apolar autoantigens displacing resident lipids within CD1a.

Conclusions:

• Skin oils, specifically squalene and wax esters, function as natural autoantigens presented by CD1a.
• This discovery reveals a novel mechanism of skin barrier immunity involving CD1a-mediated presentation of oily autoantigens.
• The findings provide new insights into T cell recognition and autoimmune responses in the skin.