CD1a is a cell surface glycoprotein that is part of the CD1 family of antigen-presenting molecules. It is primarily expressed on Langerhans cells, a type of dendritic cell found in the epidermis of the skin, as well as on certain T-cell leukemias and thymocytes. CD1a is involved in the presentation of lipid antigens to T-cells, particularly to a subset of T-cells known as invariant natural killer T （iNKT） cells. CD1a plays a crucial role in immune responses, particularly in the initiation and amplification of local and systemic events during skin inflammation. It has been shown that CD1a can capture endogenous cellular lipids that broadly block T cell responses, suggesting its role in regulating immune reactions. In conditions such as atopic dermatitis and psoriasis, CD1a expression and reactivity have been linked to disease pathology. Moreover, CD1a has been implicated in the pathogenesis of various diseases, including mycobacterial infections and certain types of cancer. It can serve as a biomarker for disease diagnosis, monitoring, and personalized treatment strategies.