IFNγ, but not IFNβ, depolarizes OPC mitochondria prior to loss of plasma membrane integrity. Representative histograms of TMRE signals in DAPI-negative OPCs at 24 h after treatment with GM alone (control, A), IFNβ (B) or IFNγ (C). More TMRE-/DAPI- OPCs were detected in the gated area (R3) in the cultures treated with IFNγ for 24 h compared to control and IFNβ-treated cultures. D, TMRE-/DAPI- OPCs became detectable between 12 and 18 h after treatment with IFNγ (closed circle). In contrast, GM alone (control, open circles) or IFNβ (closed triangles) did not increase this population until 24 h after treatment. ** Indicates p < 0.01 compared with control.