In addition to promoting brain tumorigenesis, IL-33 promotes M2 macrophage skew and/or Treg expansion and activation to establish an anti-inflammatory microenvironment against diseases, especially MS, AD, trauma, ischemic stroke, and hemorrhage (Figure 2), which suggests that IL-33 administration is an appropriate and desired therapeutic treatment against CNS diseases. Here, IL33 is linked to myeloid sarcoma.