Usually the immune system identifies defective cells.
Researchers from the University of California in San Diego identified the molecular mechanism that determines whether to respond with a malignant tumor for immunotherapy. It turned out that some patients are refractory to treatment due to the fact that cancer cells have a particular protein on its surface.
Usually the immune system identifies defective cells that may lead to the development of cancer, and destroys them with the help of T cells. However, tumor cells may begin to synthesize the protein PD-L1 to deceive the lymphocytes having on its surface the protein PD-1. It is proved that drugs targeted to block the interaction of PD-L1 with PD-1, is effective in the fight against cancer, but for some patients they are useless.
Scientists have found that some tumor cells have not only PD-L1, but PD-1, resulting in these proteins interact with each other. Happens the neutralization of the “deceptive” protein that can no longer deactivate T cells. Thus, patients with high levels of PD-1 in cancer cells do not respond to blocking PD-L1 antibodies. According to researchers, these types of tumors employ as yet unknown mechanisms that allow them to avoid attack by the immune system.
Experts plan to continue research to identify other ways of cheating T-lymphocytes cancer cells.