Microglia, because of their phagocytic nature, are expected to be involved in all neurodegenerative diseases. There are literature reports that Tau-2 selectively stains a subset of microglia in diseased brain (Odawara, et al., 1995), and we have observed the same with Tau-66. Tau-66 stains all of the recognized microglial categories: resting, activated, and phagocytosing. Such cells are numerous in affected regions in AD, PSP, and CBD, and are occasionally present in control brains. In the image below, taken from the pons of a PSP case stained with Tau-66, two ramified microglia (arrowheads) appear along with two phagocytosing microglia (asterisks).

Reference: Streit, 1995