CD1A encodes CD1a, a non-polymorphic glycoprotein that presents lipid antigens to T cells, particularly αβ T cells 1. CD1a is abundantly expressed on Langerhans cells in the epidermis and serves as a lipid antigen-presenting molecule crucial for skin immunity and homeostasis 12. The protein presents both endogenous self-lipids and foreign lipid antigens, including bacterial lipopeptides from Mycobacterium tuberculosis, through ternary CD1a/antigen/TCR interactions 13. Mechanistically, CD1a can activate T cells through two distinct pathways: classical antigen presentation where lipids protrude to form TCR epitopes, and lipid-independent recognition where TCRs bind directly to the CD1a protein surface 45. CD1a-restricted T cells constitute approximately 1% of skin T cells and are involved in responses to contact dermatitis allergens, including compounds found in cosmetics and botanical extracts 45. Clinically, CD1a-mediated immunity is implicated in inflammatory skin diseases including psoriasis, atopic dermatitis, and allergic contact dermatitis, making it a potential therapeutic target 126.