Prolonged illnesses like cancer and chronic infections often leave the immune system in a state of exhaustion, where its frontline defenders—T cells—lose their ability to function effectively. Research, led by the Peter Doherty Institute for Infection and Immunity (Doherty Institute) and the Peter MacCallum Cancer Center (Peter Mac), have identified a rare type of immune cells, called stem-like T cells, that holds the key to maintaining powerful, long-term immune responses.

The study revealed that the endurance of these stem-like T cells is fuelled by a protein called ID3, expressed by a gene of the same name. These ID3+ T cells have a unique ability to self-renew and resist exhaustion, giving them the power to sustain immune responses far longer than other T cells that don’t express ID3.