Here, we describe that following transient middle cerebral artery occlusion (tMCAO), CXCL13 is expressed by activated cerebral blood vessels, which contributes to the recruitment of CD4+ ICOS-1+ CXCR5+ IL-21 producing T follicular helper cells (TFH) into the brain during the reperfusion phase of the disease. The gene discussed is IL21; the disease is medical procedure.