Little is known about the participation of β chemokines in inflammatory processes within the central nervous system. The release of three of these peptides (macrophage inflammatory protein [MIP]-1α, MIP-1β, and monocyte chemoattractant protein-1) from human fetal microglial cell and astrocyte cultures was assessed following stimulation by lipopolysaccharide, interleukin-1β, and tumor necrosis factor-α. Although striking differences were found between these two types of glial cells in their responsiveness to lipopolysaccharide and cytokines, both microglia and astrocytes produced all three β chemokines. Only microglial cells, however, demonstrated an increased migratory response to the β chemokines. The results of this in vitro study suggest that β chemokines may play an important role in the trafficking of mononuclear phagocytes within the brain.