The natural killer (NK) cell is a new target for regulatory T (T reg) cell tyranny, according to a study on page 1075. Ghiringhelli and colleagues show that the antitumor activity of NK cells is snuffed out by T reg cells, allowing tumors to grow unchecked.
NK cells are innate immune cells that help destroy NK cell–sensitive tumors, such as melanomas and gastrointestinal tumors, which express activating ligands for these cells. The activation and antitumor functions of NK cells are triggered by the binding of these ligands to the activating receptor NKG2D on the NK cells. In many cancer patients, NK cell activity is hampered by the shedding of NKG2D ligands from tumor cells or by other unknown mechanisms.
This group recently showed that a drug that activates NK cells in patients with gastrointestinal cancer improved their prognoses. They now report that the patients...
