Natural killer cells are "not T not B lymphocytes" with what is usually a granular morphology which can kill certain tumour cells. NK cells play an important role in the acquired immunity to viruses and other intracellular pathogens as well as in antibody-dependent cellular cytoxicity.

Necrosis: The death of cells or tissue as a consequence of chemical physical damage is called necrosis. It is distinct from apoptosis, the biologically programmed cellular death. In contrast to apoptosis, necrosis results in large quantities of cellular refuse which must be eliminated by phagocytes.

Neurodermatitis appears in the form of an itching skin eczema. There is a usually an intolerance to a number of allergens. The chronic illness reappears in phases without a recognizable cause. The inflammatory skin phenomena often show up after stress and other psychological strains.

Neutrophile leukocytes or neutrophile polymorphonuclear leukocytes (granulocytes) are a group of white blood cells in the peripheral blood of humans. They possess a strongly lapped nucleus and neutrophile granulomas. These are phagocytes which play in important role in the ingestion and destruction of extracellular pathogens.