*3.1.6 Natural killer cells*

A type of innate lymphoid cell (ILC) that is important in innate immunity to viruses and other intracellular pathogens and in antibody-dependent cellular cytotoxicity (ADCC) hypersensitivity reacyions.

They do not express antigen receptors and are considered part of the innate immune system, despite being lymphoid cells [19, 20].
