Given that CD83 is a marker of mature dendritic cells, with complex, bidirectional interactions with diverse pathogens6, 7, 8 and its role in activated microglia during neuroinflammation,9 we hypothesized that CD83(+) AD subjects may differ from CD83(−) AD subjects on the basis of a microbial or immunological perturbation. Here, CD83 is linked to Alzheimer disease.