Microglia are the primary immune effector cells of the CNS. Pathological changes in the brain or spinal cord cause rapid microglial migration to the affected area where they undergo phenotypic and morphologic transformation. If sufficiently activated, these cells also release chemotactic and inflammatory cytokines that signal the recruitment of monocytes from the circulation into the pathological CNS (Davalos et al., 2005; Nimmerjahn et al., 2005).
