Interleukin-1 is an astroglial growth factor in the developing brain.

The immunomodulator interleukin-1 (IL-1) is found to be an astroglial growth factor during development of the mammalian brain. In vitro studies indicate that ameboid microglia, a class of brain mononuclear phagocytes, are the likely source of IL-1. Examination of different brain regions during development shows IL-1 production only after the appearance of ameboid microglia. These observations suggest that brain mononuclear phagocytes secrete growth factors that regulate normal growth and development of the CNS.