Natural killer cells, or NK cells, are always on the forefront in the constant battle to protect the body against infections and viruses. They are essential for the human immune system, and now scientists are looking at ways of incorporating them in new immunotherapies designed to tackle some of the most deadly diseases, including cancer.
One recent study, the result of a joint project between researchers at Lund University in Sweden, University of Oxford and Karolinska Institutet in Stockholm, details the different steps in the maturation process of these supercells. They are a subgroup of cytotoxic lymphocytes (white blood cells) and can originate from different areas of the body, the bone marrow, lymph nodes, spleen, tonsils, and thymus, where they then enter into the circulation.
Similar to T and B lymphocytes, two other important players in the immune system, NK cells provide rapid responses to viral-infected cells and it’s their job to detect and control early signs of cancers. NK cells were first noticed for their ability to kill tumor cells without any priming or prior activation (in contrast to cytotoxic T cells, which need priming by antigen presenting cells). In fact, this is how they got their name, from “natural” killing.
The team discovered that NK production and development was linked to Notch signaling, a conserved pathway that regulates cell-fate determination during development and maintains adult tissue homeostasis. Mouse models where the Notch function has been inactivated in the blood cells had reduced NK numbers and their function appeared to be affected.
“Without Notch signalling, the NK cells did not mature normally and their numbers were reduced. This could be significant for the NK cells’ ability to fight cancer and infections”, explains Ewa Sitnicka, one of the study leaders.
Understanding the mechanisms behind NK cell production and maturation could open the door for improved immunotherapies, especially against cancers.