Doublecortin expression in CD8+ T-cells and microglia at sites of amyloid-β plaques: A potential role in shaping plaque pathology?

Abstract One characteristic of Alzheimer's disease is the formation of amyloid-β plaques, which are typically linked to neuroinflammation and surrounded by inflammatory cells such as microglia and infiltrating immune cells. Here, we describe nonneurogenic doublecortin (DCX) positive cells, DCX being generally used as a marker for young immature neurons, at sites of amyloid-β plaques in various transgenic amyloid mouse models and in human brains with plaque pathology. The plaque-associated DCX+ cells were not of neurogenic identity, instead most of them showed coexpression with markers for microglia (Iba1) and for phagocytosis (CD68 and TREM2). Another subpopulation of plaque-associated DCX+ cells was negative for Iba1 but was highly positive for the pan-leukocyte marker CD45. These hematopoietic cells were identified as CD3-and CD8-positive and CD4-negative T-cells. Peculiarly, the DCX+/Iba1+ microglia and DCX+/CD8+ T-cells were closely attached, suggesting that these two cell types are tightly interacting and that this interaction might shape plaque pathology.