Although it currently remains unclear if mice possess an equivalent population of highly IFN-driven CD4 T cells, several papers have found evidence for expansion of activated, IFN-responsive CD8 T cells in the brain in several AD models, including the tau P301S-APOE4 (“TE4”) knock-in model (5) and the 5XFAD model (23). Here, APOE is linked to Alzheimer disease.