p150/95 (CD11c/CD18, CR4) is a member of the β2-integrin family of adhesion molecules and is considered an important phagocytic receptor. The role of p150/95 in the development of central nervous system demyelinating diseases, including multiple sclerosis, remains unexplored. To determine p150/95-mediated mechanisms in experimental autoimmune encephalomyelitis (EAE), we performed EAE using CD11c-deficient (CD11c-/-) mice. EAE in CD11c-/- mice was significantly attenuated and characterized by markedly reduced spinal cord T-cell infiltration and interferon-γ production by these cells. Adoptive transfer of antigen-restimulated T cells from wildtype to CD11c-/- mice produced significantly attenuated EAE, whereas transfer of CD11c-/- antigen-restimulated T cells to control mice induced a very mild, monophasic EAE. T cells from MOG35-55 peptide-primed CD11c-/- mice displayed an unusual cytokine phenotype with elevated levels of interleukin (IL)-2, IL-4, and IL-12 but reduced levels of interferon-γ, tumor necrosis factor-α, IL-10, IL-17, and transforming growth factor-β compared with control mice. Overall, CD11c-/- T cells from primed mice proliferated comparably to that of control T cells on MOG35-55 restimulation. Our results indicate that expression of p150/95 is critical on both T cells as well as other leukocytes for the development of demyelinating disease and may represent a novel therapeutic target for multiple sclerosis. Copyright © American Society for Investigative Pathology.