Weill Cornell Medicine researchers have discovered that PD-1—a molecule best known for putting the brakes on immune cells—also plays a critical role in helping T cells become long-term immune defenders in the skin. Early during infection, PD-1 acts like a steering wheel, guiding T cells to become protective resident memory T cells (TRM) that stay in place. These cells remember invading germs or cancer and quickly mount a response if that enemy reappears.

The preclinical ...