Pre-clinical evidence for positive anti-inflammatory effects of sPD-L1 via PD-1 agonism now exists for ischemic stroke [22,23], intracerebral hemorrhage (ICH) [24], subarachnoid hemorrhage (SAH)-related vasospasm [25], and traumatic brain injury [26] (TBI). Here, PDCD1 is linked to subarachnoid hemorrhage.