Killer cells are special Defence cells of the immune systemwhich specifically destroy diseased or infected body cells. There are two main types:
- Natural killer cells (NK cells):
- are part of the innate defence system
- recognise and destroy cells that are infected by viruses or degenerate (e.g. cancer cells)
- Killer T cells (cytotoxic T lymphocytes):
- are part of the acquired defence
- are activated by helper cells
- specifically kill cells that are infected by certain pathogens (e.g. HIV, influenza viruses)
