Lymph nodes were harvested from WT mice that had been immunized 10 days earlier with MOG35–55+CFA. (A) Whole lymph node cells were stimulated with MOG35–55 and IL-23 for 4 days. Afterwards CD4+ T cells were isolated and transferred to either WT or IL-17R −/− naïve recipients (5×106 cells/host i.p.). (B) WT (left) or IL-17R −/− (right) mice that received Th17 polarized CD4+ T cells were sacrificed at peak disease. CNS specimens were harvested, fixed, sectioned, and stained with H&E. Upper panels, magnification 4×; lower panels, 40×. Bar 50µm. Data are representative of 4 independent experiments with 5–7 mice/group.