The central nervous system as an immunocompetent organ: role of glial cells in antigen presentation.

The central nervous system has the capacity to initiate and regulate immune responses by allowing restricted entry of peripheral immune cells and providing a microenvironment that is conducive to the activation of immune effector cells. In this commentary, we discuss the ability of two glial cell types, astrocytes and microglia, to function as APCs. In particular, we focus on the phenotypic and functional distinctions between astrocytes and microglia that may contribute to their differing abilities to effectively present Ag to CD4+ cells.