CD4 and Alzheimer disease: Specifically, the well-known autoimmune demyelinating disease, multiple sclerosis (MS) [6], is a prototypical abnormal T cell immune-induced CNS pathology, however, CD4+FoxP3+ regulatory T cells (Tregs) can be exploited to exert ameliorative effects in neuro-degenerative diseases, such as cerebral ischemia [7], Alzheimer's disease (AD) [8], and Parkinson's disease (PD) [9].