Interleukin-1 injected into mammalian brain stimulates astrogliosis and neovascularization.

Interleukin-1 (IL-1), a protein produced by mononuclear phagocytes, helps to initiate the inflammatory response through its action upon a diverse population of cells. Recently this immunomodulator has been detected at sites of traumatized brain. As reported here, recombinant forms of IL-1 injected into the cerebral cortex of adult rats elicit not only astrogliosis but also new blood vessel growth. These responses are typical of brain injury and suggest that IL-1-secreting inflammatory cells may mediate wound healing in the CNS.