CD22 and Alzheimer disease: Interestingly, the terminal sugar residue on glycoproteins and glycolipids, sialic acid (SA), plays a role in regulation of microglia activities including phagocytosis and secretion of cytokines through several different pathways, including activation of SA receptors (Siglecs) like CD22 and CD33 that are associated with aging and AD risk [7, 8, 9] Therefore, investigating localization of sialylated glycans within the AD brain is a crucial first step to understand the relationship between SA and AD neuropathology.