CD4 and hemorrhagic stroke: To explore the causes and potential mechanisms in which peripheral blood CD4+ T cells are involved in patients who suffered a severe hemorrhagic stroke, we analyzed the lymphocytes subset of CSF and blood in 11 patients with cerebral parenchymal hemorrhage breaking into the ventricular system or subarachnoid space (Figures 4A–E), and the outcomes revealed that the median total number of lymphocytes in CSF was 248.06/μL (IQR 74.40/μL–490.35/μL) (Figure 4A).