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The Importance of Natural Killer Cells in Cancer Immunology
June 15, 2023 Kiran Nagra

The Importance of Natural Killer Cells in Cancer Immunology

In the realm of cancer immunology, natural killer (NK) cells emerge as essential warriors in our immune system. These remarkable cells play a pivotal role in identifying and eliminating infected or cancerous cells. In this blog post, I will explore the scientific intricacies of NK cells, including their production, killing mechanisms, and the vital nutrients required for their development. Join me as I delve into the significance of NK cells in the fight against cancer.
The Basics of NK Cells: NK cells are a type of white blood cell that belongs to the innate arm of the immune system. They serve as a crucial first line of defence against infected or cancerous cells. Unlike other immune cells, which are typically produced in the bone marrow, NK cells are primarily generated by the cells of the acquired immune system. Specifically, lymphoid progenitor cells, which also give rise to T-cell and B-cell precursor cells, play a key role in NK cell development.
Unlike T cells, NK cells do not require training in the thymus nor possess memory of previous exposures. However, NK cells exhibit potent killing abilities without the need for antigen presentation. They accomplish this by releasing perforins and granzymes, which induce apoptosis (cellular self-destruction) in their target cells. Apoptosis is a natural process that helps maintain healthy cellular turnover within our bodies.
The Absence of Apoptosis in Cancer Cells: Cancer cells evade apoptosis, contributing to their uncontrolled growth. The ability of NK cells to induce apoptosis in cancer cells makes them an exciting prospect in cancer treatment. By harnessing the power of NK cells, we can potentially induce apoptosis in cancer cells and inhibit their growth.
The Role of MHC-I and NK Cell Activation: To understand how NK cells identify their targets, let's use an analogy. Imagine cells as having arm-like projections called major histocompatibility complex class I (MHC-I). These projections help NK cells distinguish healthy cells from sick cells. NK cells constantly patrol and contact other cells. Whether or not an NK cell kills a cell depends on a balance of signals from activating and inhibitory receptors on its surface.
Activating Receptors and Inhibitory Receptors: Think of activating receptors as the triggers that ignite the fighting spirit of NK cells. These receptors recognise specific molecules expressed on the surface of cancer cells and infected cells, effectively "switching on" the NK cells and priming them for battle. However, to maintain precision and prevent unnecessary harm, inhibitory receptors act as a check on NK cell killing. Most healthy cells display MHC-I receptors, marking themselves as "self" to avoid accidental attack. The inhibitory receptors on NK cells recognize these MHC-I markers, effectively "switching off" the NK cells and preventing them from killing healthy cells. Unfortunately for cancer cells and infected cells, they often lose their MHC-I expression, rendering them vulnerable to the relentless assault of NK cells.
The Role of MHC-I and NK Cell Activation: Imagine our immune cells as vigilant soldiers patrolling the battlefield of our body. One key aspect of their surveillance system is a set of arm-like projections called major histocompatibility complex class I (MHC-I) molecules, which act as identification markers on the surface of our cells. These markers help natural killer (NK) cells distinguish between healthy cells and those that are infected or cancerous. As the NK cells constantly make contact with other cells, their fate is determined by a delicate balance of signals from activating and inhibitory receptors on their surface.
Activating Receptors and Inhibitory Receptors: Think of activating receptors as the triggers that ignite the fighting spirit of NK cells. These receptors recognise specific molecules expressed on the surface of cancer cells and infected cells, effectively "switching on" the NK cells and priming them for battle. However, to maintain precision and prevent unnecessary harm, inhibitory receptors act as a check on NK cell killing. Most healthy cells display MHC-I receptors, marking themselves as "self" to avoid accidental attack. The inhibitory receptors on NK cells recognize these MHC-I markers, effectively "switching off" the NK cells and preventing them from killing healthy cells. Unfortunately for cancer cells and infected cells, they often lose their MHC-I expression, rendering them vulnerable to the relentless assault of NK cells.
The Killing Mechanism: Once an NK cell receives the green light to eliminate a target, it unleashes its formidable weaponry. Cytotoxic granules, packed with potent molecules, are released by the NK cell. Among these molecules are perforin and granzymes, which work in harmony to execute their deadly mission. Perforin acts as the architect of destruction, creating tiny holes in the target cell's membrane, breaching its defences. Through these perforations, the granzymes gain entry and unleash their devastating power. Granzymes induce apoptosis, a process of programmed cell self-destruction, within the target cell. This lethal combination ultimately leads to the breakdown and lysis of the target cell, effectively neutralising the threat and preserving the health of our body.
Nutrients for NK Cell Development and Function: To ensure the proper development, proliferation, and activity of NK cells, a steady supply of essential nutrients is crucial.
Vitamin A: Vitamin A is a powerful contributor to NK cell activity. It acts as a key regulator of gene expression and plays a vital role in the differentiation and maturation of NK cells. Moreover, vitamin A promotes the production of cytokines and enhances the cytotoxic capabilities of NK cells, enabling them to effectively eliminate target cells.
Vitamin D: Vitamin D, often referred to as the "sunshine vitamin," is essential for maintaining optimal NK cell function. It acts as a hormone and plays a crucial role in modulating the immune response. Vitamin D supports the maturation of NK cells and enhances their cytotoxicity against infected or cancerous cells.
Zinc: Zinc is an essential mineral that acts as a cofactor for numerous enzymes involved in the synthesis and functioning of immune cells, including NK cells. Zinc deficiency has been associated with impaired NK cell activity and decreased immune response. Adequate zinc levels are crucial for the optimal development and functioning of NK cells.
Selenium: Selenium is a trace mineral that plays a vital role in immune cell function, including NK cells. It acts as a cofactor for antioxidant enzymes, helps regulate gene expression, and enhances NK cell activity. Selenium deficiency can compromise the cytotoxic capabilities of NK cells and impair their ability to combat infections and cancer.
Supplements for Boosting NK Cell Activity: In the pursuit of enhancing NK cell function, supplements like Ribraxx/Biobran, derived from fermented rice bran, have shown promise. These supplements contain bioactive components that can stimulate and enhance NK cell activity. By providing an additional boost to the body's natural defences, these supplements support NK cell function and contribute to a robust immune response against infections and cancer. Another favourite product of mine is Panaxea's Resist, Resist is formulated with seventeen powerful immune boosting and modulating herbal extracts. it strengthens the innate immune system by increasing NK cells, macrophages phagocytes and leucocytes (WBC) in the spleen and thymus.
The Role of Micronutrients and NK Cell Function: Micronutrients, including vitamins and minerals, have a profound impact on NK cell function. Abnormalities in NK cell function, which often accompany ageing, can be attributed to changes in the microenvironment, endocrine factors, and nutritional status. Maintaining an optimal nutritional profile, with a focus on sufficient intake of key micronutrients, is vital for supporting robust NK cell activity and ensuring an effective immune response.
For cancer patients, the significance of nutrient repletion and maintaining a steady state of essential nutrients cannot be overstated. NK cells are key players in the immune system's defence against cancer. By ensuring adequate nutrient intake, including vitamins A, D, zinc, and selenium, cancer patients can support the production, proliferation, and activity of NK cells, ultimately aiding in their fight against the disease.
Caloric Restriction and NK Cell Function: While fasting has gained popularity, it is important to note that extended fasting or caloric restriction in mice studies has been shown to reduce NK cell activity. Mice subjected to caloric restriction exhibited alterations in the distribution and responsiveness of NK cells. Although their cytotoxic activity against target cells was still present, the reduced NK cell function may impact overall immune responses.
Natural killer cells are remarkable players in our immune system, wielding their cytotoxic abilities to combat infected cells and cancers. By understanding the intricacies of NK cell biology, we gain insights into potential therapeutic avenues for cancer treatment. The role of nutrients, such as vitamin A, zinc, and selenium, in supporting NK cell development and function highlights the importance of a balanced diet. Maintaining optimal NK cell activity can contribute to a robust immune response, reinforcing our body's defence against diseases. With ongoing research, I can only hope that it unlocks even more potential in harnessing the power of NK cells for improved cancer care and beyond.
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