CD4 and Alzheimer disease: We then isolated CD4+ spleen cells from 4‐ and 9‐month‐old APPtgp38fl/flLysM‐Cre+/− and APPtgp38fl/flLysM‐Cre−/− littermate mice, and observed that p38α‐MAPK deficiency significantly reduced the transcription of Il‐17a, but not Ifn‐γ, Il‐4 and Il‐10 in AD mice at the age of 9, but not 4 months (Figure 6a–d).