In moderate AD, CTLA-4 + CD8 + T cells are positively correlated with total tau (p = 0.0153), p- tau (p = 0.0277) and the number of CD28 + CD8 + T cells are negatively correlated with p-tau (p = 0.0336) and, like in mild AD (p = 0.0165), with Amyloid-β 1–40 (p = 0.0240). Here, CTLA4 is linked to Alzheimer disease.