In subarachnoid hemorrhage, the inflammatory response has been associated with rats containing elevated levels of pro-inflammatory cytokines, including TNF-α and IL-1β, in both serum and brain tissue, as well as IL-1β, IL-4, IL-6, IL-8, IL-10, IL-15, IL-17, IL-18, TNF-α, MCP-1 (macrophage chemotactic protein-1), and VEGF (vascular endothelial growth factor) in cerebrospinal fluid during the first 7 days [9]. Here, IL4 is linked to subarachnoid hemorrhage.