Our clinical data showed an increase of circulating CD3+CD8−IL-17A+IFNγ− Th17 cells in subjects with MCIAD and an association of CD4+CD25+CD127low Tregs with the neurodegeneration markers phospho and total Tau, which complements the observations from fundamental research, that the adaptive immune system seems to be involved in the pathogenesis of AD and its neuropathological changes especially in the early stages of the disease. Here, CD4 is linked to Alzheimer disease.