Importantly, CD103–CD8+ Trm cells accumulating in the brains of AD patients and 3xTg-AD mice were characterized by no significant increase in Gzmb and Prf1 expression combined with the strong expression of Gzmk and high levels of GrK protein (but low levels of GrA and GrB proteins, a distinct phenotype for CD8+ Trm cells in AD. This evidence concerns the gene PRF1 and Alzheimer disease.