cancer
Defenses Against Cancer
Immune checkpoints
Even when the immune system is functioning normally, cancer can escape the immune system’s protective surveillance. One reason the immune system usually does not attack normal cells is that the surface of normals cells carries proteins that signal to circulating immune cells (T cells) that the cell bearing them is normal and should not be attacked. These are called checkpoint proteins. Sometimes cancer cells develop the ability to produce one or more of these checkpoint proteins and thus escape from attack. Newer types of cancer medications called checkpoint inhibitors can block the signal and allow the immune system to attack the cancer. 