CD4 and Alzheimer disease: Our research discovered four immune phenotypes linked to Treg cells (CD25++ CD45RA- CD4 not regulatory T cell % T cell, CD25++ CD45RA- CD4 not regulatory T cell % CD4+ T cell, Secreting CD4 regulatory T cell Absolute Count and Activated & secreting CD4 regulatory T cell Absolute Count), suggesting that Treg cells may play a significant protective role in the progression of AD.