CD4 and Stroke: Moreover, IL-17A+ T lymphocytes were detected in the post-mortem tissue of patients that died shortly after their stroke (Gelderblom et al., 2012) and IL-21-producing CD4+ T cells, potentially Th17, Tfh, or Th9 cells, were found surrounding the infarcted tissue area in post-mortem tissue of patients with acute stroke (Clarkson et al., 2014).