When does T cell exhaustion occur?

T-cell exhaustion refers to a state in which T-cells lose their ability to kill cancer cells or cells infected with a virus. This typically occurs when the body’s immune system stays active for extended periods of time such as when a person has cancer or any chronic infection. 

CD8+ T-cells may get exhausted in a matter of days or weeks from the time effector T-cells get exposed to chronic antigen stimulation. This commonly occurs in a tumor microenvironment in which the T-cells are exposed to persistent antigen and/or inflammatory signals.

The surface of exhausted T cells have high amounts of immune checkpoint proteins, which is responsible for suppressing the activity of the T cells. Drugs prescribed as part of cancer treatment target these proteins, allowing the T cells to more easily identify and kill the cancer cells.