CD1c

CD1c is a group 1 CD1 molecule expressed predominantly by human conventional dendritic cells (cDC2) and functions as a lipid antigen-presenting molecule that activates antigen-specific T-cell responses through presentation of structurally diverse endogenous and microbial lipids^[1][2]. Mechanistically, CD1c participates in adaptive immune regulation by presenting mycobacterial lipids, phosphatidylinositol, phosphatidylcholine, sulfatides, and lipopeptide antigens, thereby supporting T-cell activation and interferon-γ production during antimicrobial immune responses^[1]. CD1c⁺ dendritic cells also produce IL-12p70, IL-1β, IL-6, and IL-23 following innate immune stimulation and promote both Th1 and Th17 effector differentiation, linking antigen presentation to inflammatory cytokine networks^[3]. In autoimmune and inflammatory settings, activated CD1c⁺ dendritic cells have been implicated in pathogenic Th1/Th17 immune responses, highlighting their relevance in disease-associated immune activation^[3]. Compared with related CD1 isoforms, including CD1a and CD1b, CD1c exhibits distinct structural features that enable presentation of a broader repertoire of lipid-based antigens, supporting functional specialization within the group 1 CD1 family^[1][2]. Within the CD1c⁺ dendritic-cell compartment, CD14⁺ and CD14⁻ subsets display divergent transcriptional and functional characteristics, with CD14⁺ populations expressing monocyte-associated markers and showing reduced T-cell stimulatory capacity^[4]. Furthermore, CD1c⁺CD163⁺ dendritic-cell subsets can prime CD8⁺CD103⁺ T cells through TGF-β signaling and are associated with tissue-resident memory T-cell responses in tumor microenvironments, supporting their utility in tumor immunology research models^[5].

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