In autoimmune pathogenesis, T cell-derived RANKL orchestrates astrocytic C-C motif chemokine ligand 20 (CCL20) biosynthesis, establishing chemotactic gradients that govern CNS T cell infiltration.194 T cell-specific RANKL knockout murine models demonstrated complete experimental autoimmune encephalomyelitis resistance through impaired neuroantigen-specific T cell CNS trafficking. The gene discussed is CCL20; the disease is experimental autoimmune encephalomyelitis.