The Really Healthy Company
The role of natural killer (NK) cells
Recent research reveals that natural killer (NK) cells could be at the centre of exciting new discoveries, which could reveal their role in determining the severity of disease.
Our immune system plays an essential role in protecting us against a wide variety of diseases, a role that is even more important at a time when we are concerned about viral infections.
Our level of immunity, or the degree of activity of our immune system, is intrinsically linked to our diet (the quality, diversity and quantity of nutrients), our lifestyle (how physically active or sedentary we are) and our levels of toxicity (the number of toxic substances circulating in our body or stored in our fatty tissue). It is well known that people with slower immune systems are more likely to succumb to illness and take longer to recover. This is because our defences are weaker and our repair mechanisms are compromised.
Immune system mediation
The immune system is not only our defence against the environment, it is also essential for maintaining the integrity and function of the body. It also provides information about the daily housekeeping tasks that are essential to keep us alive.
Our primary immune response is mediated by lymphocytes (white blood cells), macrophages, mast cells, hormones and other messengers circulating in the blood and lymphatic systems.
NK cells are a type of lymphocyte, the white blood cells that form part of the innate immune system (they have no memory of the infection but act purely by instinct in the moment). This instinctive branch of our immune response is the first line of defence against the environment and foreign invaders (such as viruses, bacteria, parasites and toxins), including Severe Acute Respiratory Syndrome (SARS), as well as tumour cells. NK cells are the most aggressive soldiers in our immune system. The motto of these microscopic captive crusaders is "seek and destroy".
NK cells are pre-programmed to seek out and destroy infected and cancerous cells. However, they do not destroy indiscriminately. They are capable of intelligently scanning the cells they come into contact with, rather like scanning a barcode, and they only destroy defective or infected cells.
Research has shown that patients with compromised (or overloaded) immune systems, or those who have undergone immunosuppressive treatment (radiotherapy and chemotherapy), have reduced NK cell activity. In fact, in patients with metastatic disease, survival time is directly correlated with the level of NK cell activity. This NK activity is also greatly reduced in autoimmune diseases and chronic fatigue syndrome.
References: Maucourant, C. et al. (2020). Natural Killer Cell immunotypes related to COVID-19 disease severity. Science Immunology. 5, eabd6832.