Stress hormone is key factor in failure of immune system to prevent leukemia -- ScienceDailyThey do this by using cortisol to force the release of a protein, latrophilin 1. This in turn causes the secretion of another protein, galectin-9, which suppresses the body's natural anti-cancer immune mechanism. Dr Sumbayev's team, working with researchers from two German universities and the UK's Diamond Light Source facility, found that although healthy human white blood cells are not affected by cortisol they become capable of releasing latrophilin 1 when malignant transformation takes place. Malignant AML cells then use cortisol to increase the release of latrophilin 1 so that they can use it to avoid the immune system. The study concluded that galectin-9, as well as a natural binding partner of latrophilin 1 -- known as FLRT3 -- which are both present in human blood plasma, are the most promising targets for future anti-AML immune therapy.