IL17A and aneurysm: This finding suggests that: (1) the aneurysmal wall may be the source of Tc17 cells seen in the subarachnoid space after aneurysm rupture; and (2) Tc17 cells may be an important source of IL-17 and pro-inflammatory cytokines both in the vascular wall of unruptured aneurysms and CSF after aSAH.