CD68 and Alzheimer disease: In late-stage human AD, microglia have increased phagocytic/scavenging capability, with increased human leukocyte antigen-DR (HLA-DR), macrophage scavenging receptor-A (MSR-A) and cluster of differentiation 68 (CD68) expression, that are negatively associated with cognitive decline [24], and cells typically exhibit a less ramified / amoeboid morphology [3].