CXCR6 and Cognitive impairment: Moreover, prior to the observation of CXCL16-CXCR6 mediated CD8 T cell infiltration in the mouse models, the CXCL16-CXCR6 axis-mediated CXCR6+ CD8 T cell homing to cerebrospinal fluid (CSF) followed by clonal expansion of the cells has been suggested in patients with cognitive impairment [15].