The results obtained by Saresella et al. (2011) regarding naive lymphocytes from AD patients have demonstrated an increase of Th17 cytokines production, including IL-21, IL-6, and IL-23 and expression of Th17 transcription factor RORγt in AD patients compared to MCI subjects and healthy control subjects (Saresella et al., 2011). Here, IL21 is linked to Alzheimer disease.