Researchers at The Ottawa Hospital and the University of Ottawa discovered that a kind of kiss between cells, called trogocytosis, plays a key role in the battle between the immune system and blood cancer cells. The findings were published on April 13, in the journal Science Advances.
Trogocytosis is a phenomenon by which immune cells, such as Natural Killer (NK) cells, make close contact with another cell and steal a chunk of its membrane.
Dr. Michele Ardolino and his team discovered that when NK cells steal membranes from blood cancer cells, a protein called PD-1 comes along for the ride and puts the NK cell to sleep, shutting down their anti-cancer activity.
"NK cells are exceptional cancer killers, and we previously discovered that PD-1 prevents them from working properly. A missing piece of the puzzle is how NK cells produce PD-1, which was surprisingly hard to address. But it seems clear that tumors hijack the process to put NK cells to sleep and evade the immune system,” said Dr. Ardolino, assistant professor at the University of Ottawa.
Drugs that block PD-1, also called PD-1 inhibitors or immune checkpoint inhibitors, are now routinely used to "wake up" the immune system and help it fight cancer cells. These drugs have significantly improved survival for people with certain kinds of skin cancer, blood cancer and lung cancer, among others.
Ardolino said their research solves a mystery about how PD-1 inhibitors work on NK cells, noting that a better understanding of this process could lead to new kinds of immunotherapy for cancer.