CD11c, also known as integrin alpha X or ITGAX, is a type I transmembrane glycoprotein and a member of the β2 integrin family. It forms a heterodimer with CD18 to create the complement receptor 4 （CR4）, which is involved in various immune functions. CD11c is highly expressed on myeloid dendritic cells （DCs）, monocytes, macrophages, granulocytes, and subsets of T and B cells. It plays a crucial role in cell adhesion, migration, and phagocytosis, and is essential for the activation of CD4+ and CD8+ T cells by DCs. Additionally, CD11c is involved in the regulation of hematopoietic stem and progenitor cells under stress conditions. It is widely used as a marker for DCs in immunological research and clinical applications.