CD1C encodes an antigen-presenting protein that binds and presents lipid and glycolipid antigens to T-cell receptors on natural killer T-cells. CD1C serves as a critical cell surface marker identifying distinct immune cell populations. In human blood, CD1C+ dendritic cells represent a major subset of conventional dendritic cells with specialized functions 1. Single-cell RNA sequencing studies have identified CD1C+CD163+ dendritic cells (DC3s) as immediate precursors of inflammatory dendritic cells, capable of priming CD8+ T cells with tissue homing signatures through TGF-β signaling 2. CD1C expression is also found on myeloid dendritic cells enriched in psoriatic epidermis 3 and in tumor-associated dendritic cells within lung adenocarcinomas 4. Beyond dendritic cells, CD1C serves as a marker for regulatory B cells (Bregs) that produce IL-10 and suppress inflammatory responses, with therapeutic potential for graft-versus-host disease 5. In human peritoneal cavities, CD1C+CD14+CD64+ cells represent a distinct population resembling conventional dendritic cells type 2 6. The protein is constitutively expressed in human myeloid dendritic cells as part of the immunoproteasome system 7.