Seducing astrocytes to the dark side.

After injury and in disease of the central nervous system (CNS), local cells called astrocytes respond with diverse molecular changes whose functional consequences are incompletely understood. A combined genomic and experimental analysis shows that classically-activated microglia, which are innate immune cells resident in CNS neural tissue, release molecules that drive astrocytes into a neurotoxic state, raising important questions about potential adaptive and maladaptive functions of such a mechanism.