Th17 cells are highly proinflammatory, secreting interleukins (IL)-17, IL-21, IL-22, and IL-23 (Maddur et al., 2012); and it has been demonstred in vitro that the Th17 cytokines, IL-21 and IL-22, and the specific transcriptional factor RORγ were significantly increased in Aβ stimulated T lymphocytes of AD patients (Saresella et al., 2011). This evidence concerns the gene IL21 and Alzheimer disease.