Rogue immune cells can infiltrate old brains

Killer T cells may dampen new nerve cell production in aged mice

T cells

UNWELCOME GUESTS  In a brain region called the subventricular zone, stem cells (purple) create new nerve cells in mice’s brains. T cells (white), which are more common in older brains (right) than young brains (left), may interfere with this process.

Paloma Navarro

Immune cells can storm into the brains of older mice, where these normally helpful cells seem to be up to no good.