NATURAL KILLER term that comes from the English and means born killer, abbreviated NK, are different lymphocytes of type T or type B, as well as the markers CD4 or CD8, which participate in immune defense. They were previously called large granular lymphocytes. Its function is the destruction of infected cells and cancer cells, in addition to regulating immune responses. They are not phagocytic cells, but destroy the cells through attack on their plasma membrane by cytolysis. These cells are thought to detect the target cell by recognition of the abnormal glucocalyx. They are also thought to recognize them when infected or tumor cells exhibit peptides of their own in a class I MHC context. NK lymphocytes are produced in the bone marrow and their function is to attack infected cells, fungi, bacteria and viruses by secreting cytokines and enzymes called perforins and granzymes to destroy target cells.
