> The new findings help clarify one detail of Shirai’s 1921 mouse study that never sat well with the naive notion of immune privilege. Shirai found that tumors

> The new findings help clarify one detail of Shirai’s 1921 mouse study that never sat well with the naive notion of immune privilege. Shirai found that tumors survived and grew when implanted in some locations in mice’s brains. But when Shirai placed tumors right next to the ventricles — now known to be the locations where the brain produces the fluid that sweeps antigens off to the immune cells — the tumors didn’t survive. So, the key experiment to reveal this fact was performed one hundred years ago, but overlooked.