MAPT and Alzheimer disease: However, even though immune enhancement achieved by checkpoint blockade has the potential to alleviate both Aβ and tau pathologies in some cases of AD, PD-1 blockade in another study failed to increase the infiltration of monocyte-derived macrophages into the brain and was unable to alter the Aβ burden (Baruch et al., 2016; Latta-Mahieu et al., 2018; Rosenzweig et al., 2019).