Shichita et al. proposed that γδ T cells, not Th17 cells, secrete proinflammatory IL-17 to aggravate I/R brain injury in the delayed phase (day 3) [109], although a previous study identified that IL-17-producing cell numbers peaked 3–5 days after injury in the ipsilateral cerebral hemispheres of patients following ischaemic stroke [110]. Here, IL17A is linked to ischemic stroke.