| CD11c (ITGAX), a leukocyte-specific integrin αX subunit of the β2 integrin family, pairs with CD18 (ITGB2) to form the αXβ2 heterodimer (CR4), predominantly marking conventional dendritic cells while also appearing on activated NK cells, monocyte subsets, and granulocytes to mediate adhesion, phagocytosis, and immune surveillance. Its structure features a von Willebrand factor type A I-domain for ligand recognition, binding iC3b, fibrinogen, ICAM-1, and CD47-deficient cells, and β-propeller/β-I-like domains that transmit bidirectional signals via talin-mediated cytoskeletal linkage. Upon ligand engagement, CD11c clusters at immune synapses, recruiting talin-1 and kindlin-3 to activate integrin inside-out conformation shifts, which trigger FAK-Src signaling cascades amplifying NF-κB and MAPK pathways for DC maturation, cytokine secretion (IL-12, TNF-α), and enhanced antigen cross-presentation via MHC class II recycling. This integrates into the CD47-SIRPα missing-self recognition axis, where CD11c-ITGB2 facilitates splenic DC phagocytosis of CD47-low apoptotic cells, licensing cross-priming of CD8+ T cells through type I IFN production and costimulatory upregulation, while Syk kinase downstream bridges phagocytosis to inflammasome activation for IL-1β release. CD11c governs T cell priming in lymphoid tissues, Th2 differentiation during helminth infection, and tolerance induction in the liver, making it invaluable for researchers sorting DC subsets in flow cytometry panels or tracking integrin dynamics in intravital imaging of antigen capture. Dysregulation via deficiency impairs adaptive immunity and worsens autoimmunity, as seen in defective Th2 responses. |
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