Immune Cells
Immune cells serve as the guardians of our bodies, defending against invaders such as viruses and foreign substances. Various types of immune cells have distinct roles within the human immune system.
The immune system is fundamental to maintaining a healthy body, as it combats diseases and eliminates malfunctioning cells. However, the immune system’s ability to protect the body from new threats by generating and activating new immune cells diminishes significantly with age.
The immune system is typically classified into two main branches: the innate and adaptive immune systems. These two systems collaborate closely, each with its own set of responsibilities and functions in safeguarding the body against illness and foreign agents.
How Your Immune System May Be Weakened?
The immune system’s effectiveness can be compromised under various circumstances. Here are some factors that can weaken the immune system:
- Poor Nutrition: A lack of essential nutrients in the diet can undermine the immune system’s ability to function optimally.
- Lack of Exercise: A sedentary lifestyle can contribute to immune system weakness. Regular physical activity can enhance immune function.
- Inadequate Sleep: Chronic sleep deprivation can impair the immune system’s ability to respond to threats effectively.
- Alcohol Consumption: Excessive alcohol intake can weaken the immune system, making the body more susceptible to infections.
- Smoking Habits: Smoking is detrimental to the immune system and can impair its ability to defend against pathogens.
- Medications and Drugs: Certain medications, especially those used in cancer treatment and immune-suppressing drugs, can weaken the immune system as a side effect.
- Chronic Stress: Prolonged stress can have a negative impact on the immune system’s function.
It’s important to maintain a healthy lifestyle and avoid factors that weaken the immune system in order to promote robust immune function and overall well-being.
Immune System
Innate Immune System
The innate immune system serves as the body’s first line of defense, swiftly launching attacks against and neutralizing invading pathogens such as viruses, bacteria, parasites, and toxins. Key components of this system include Natural Killer (NK) cells and Dendritic Cells (DC). Additionally, the innate immune system involves several other types of cells, each with distinct functions that collectively form a robust defense system. These cells include macrophages, mast cells, neutrophils, basophils, and eosinophils, and they work in concert to provide a highly intricate and effective immune response.
Adaptive Immune System
The adaptive immune system constitutes the second line of defence, and it is highly specific in its responses. It is activated and summoned into action by the innate immune system when needed. The name “adaptive” is derived from its ability to adapt and change in response to exposure to specific microbes that the innate immune system cannot combat effectively. Two primary types of cells within the adaptive immune system are B cells and T cells. These cells play a central role in recognising and targeting specific pathogens and provide a tailored defence against these threats.
Types and Functions of Immune Cells
Natural Killer (NK) Cells
Natural Killer (NK) Cells live up to their name as robust and assassin-like immune cells. They possess the ability to identify infected or abnormal cells and carry out multiple actions to eliminate them. NK cells can create pores or holes in the targeted cells, leading to their destruction, or they can induce programmed cell death (apoptosis) in the affected cells. Remarkably, NK cells remove these compromised cells without triggering a more extensive immune response, making them valuable components of the immune system’s defense mechanism.
Dendritic Cells
(DC)
Dendritic Cells (DC) are often referred to as professional antigen-presenting cells. An antigen is any substance that can stimulate an immune response. While other cells can also present antigens, dendritic cells are particularly efficient in this role. They act as a crucial bridge between the innate immune system and the adaptive immune system, facilitating communication and coordination between the two branches of the immune response. This makes dendritic cells central players in the immune system’s ability to recognise and respond to specific threats.
Macrophage
Macrophage is a large white blood cell that plays a vital role in our immune system. Often referred to as a “big eater,” it functions by eliminating bacteria through phagocytosis, a process that involves engulfing, ingesting, and subsequently destroying bacteria or viruses using enzymes.
T Cells
T cells identify and eliminate cells that have been infected by pathogens or have turned cancerous. They facilitate and directly engage in the destruction of virus-infected cells, making them a crucial component of the host’s immune response against various pathogens.
B Cells
B cells have the capability to differentiate into plasma cells, specialised immune cells that are responsible for producing antibodies targeted against specific antigens. These antibodies play a pivotal role in recognising and binding to particular pathogens, effectively marking them for destruction by the immune system.
Interaction of Immune Cells
The Importance of NK Cells
- Natural Killer (NK) cells are often considered the “first responders” when it comes to cancerous cells. They act swiftly in recognising and eliminating these abnormal cells even before the T cells are mobilised into action [1]. Additionally, NK cells play a crucial role in controlling infections and providing an initial defence against pathogens before the adaptive immune system mounts a response.
- A study conducted over an 11-year period, involving 92 men and 62 women, revealed that individuals with low natural killer (NK) cell activity had higher cancer incidence rates when compared to those in the medium and high NK activity groups[2]. This suggests that NK cell activity may have a protective effect against the development of cancer.
- Cancers and viral infections have been known to develop evasion tactics to avoid T cell recognition[3]. However, NK cells have the ability to target and eliminate cancer cells by distinguishing differences between cancerous and normal cells[4]. This underscores the potential benefit of increasing the number of NK cells to enhance their function and potentially improve the effectiveness of cancer treatment.
- NK cells have a relatively short life span, typically around 2 weeks. This characteristic contributes to a lower likelihood of causing dangerous side effects, as they do not persist in the body for an extended period. Furthermore, NK cells are generally less likely to induce side effects compared to treatments like chemotherapy and radiotherapy, primarily because NK cells do not target or attack healthy cells[5]. This specificity in targeting only abnormal or infected cells is a valuable feature of NK cell-based therapies.
- Senescence, a cellular response characterised by the cessation of cell division, can be potentially harmful in certain situations. Interestingly, NK cells play a role in promoting the removal of senescent cells[6]. This highlights the role of NK cells in maintaining tissue and cellular health by assisting in the elimination of aged or dysfunctional cells.
What is Cancer?
Cancer cells indeed represent mutated cells, but not all mutations lead to cancer. Non-engineered Natural Killer (NK) cells have the capacity to eliminate mutated cells, but their effectiveness in eradicating an entire tumor can be limited. Tumors consist of a cluster of cancerous cells that have grown together, and within a tumor, there can be various types of cancerous cells.
The treatment of tumors typically involves a combination of approaches, such as surgery to remove the tumor, radiotherapy to target cancer cells with radiation, chemotherapy to use drugs to combat cancer, and immunotherapy to stimulate the body’s immune system to fight against the tumor. The specific treatment method used depends on the type, location, and stage of the tumor.
Immunotherapy
Immunotherapy is a treatment method for cancer that activates immune response in your body, as well as to teach your immune system how to identify and destroy cancerous cells. Immunotherapy can be divided into (1) drug based and (2) cell-based.
- Drug-Based Immunotherapy: This approach, such as checkpoint inhibitors, works by releasing a natural brake on the immune system. This enables immune cells, particularly T cells, to recognise and initiate an attack on tumors.
- Cell-Based Immunotherapy: This method involves using immune cells directly. An example is CAR T-cells therapy, where a patient’s T cells are engineered in a laboratory to bind to specific cancer cells and eliminate them. Other cell-based immunotherapies include the use of dendritic cells (DC) and natural killer (NK) cells, among others.
Why Should You Store Your Immune Cells?
- Ex vivo expansion refers to the process of expanding or growing a patient’s own immune cells outside the body in a laboratory setting. This is done to obtain a larger quantity of these cells, which can then be infused back into the patient’s body. The advantage of ex vivo expansion is that it allows for the generation of a significant number of immune cells that can be used for therapeutic purposes, such as cancer treatment or immunotherapy, without the risk of rejection because the cells are derived from the patient’s own immune system.
- As we age or face illness, cells in our body can indeed experience ageing and exhaustion. This can manifest in various ways, including a decrease in the efficiency and functionality of cells.
- Immune cells play a crucial role in rebuilding and strengthening the body’s immunity to protect against various threats, including mutated cells, at all times. They are responsible for recognising and eliminating abnormal or infected cells, thereby preventing diseases and maintaining overall health.
Who Should Store Immune Cells?
The immune system typically reaches its peak functional level around the age of 20, and its efficiency tends to decrease as people grow older. As the immune system weakens with age, the risk of developing various diseases, including infections and age-related conditions, becomes higher. Consequently, it’s important for young and healthy adults to consider measures to support and maintain their immune health.
NK Cells and Covid-19
The FDA has granted approval for clinical trials involving the use of NK cells in the treatment of COVID-19. This clearance has paved the way for phase I/II clinical trials that will involve 86 critically ill COVID-19 patients.
Studies have indicated that natural killer (NK) cells become robustly activated during viral infections, irrespective of the class of the virus. These activated NK cells exhibit a range of biological activities that enable them to recognize and eliminate infected cells[6]. This research underscores the potential of NK cell-based therapy as a promising approach for the treatment of viral infections, including COVID-19.
References
- O’Connor, G. M., Hart, O. M., & Gardiner, C. M. (2006). Putting the natural killer cell in its place. Immunology, 117(1), 1-10.
- Imai, K., Matsuyama, S., Miyake, S., Suga, K., & Nakachi, K. (2000). Natural cytotoxic activity of peripheral-blood lymphocytes and cancer incidence: an 11 year follow-u study of a general population. The lancet, 356(9244), 1795-1799.
- Garrido, F., Aptsiauri, N., Doordujin, E. M., Lora, A. M. G., & van Hall, T. (2016). The urgent need to recover MHC class I in cancers for effective immunotherapy. Current Opinion in Immunology, 39, 44-51.
- Lynda, AK. (2017). NK Cells in Cancer Immunotherapy, Natural Killer Cells, Mourad Aribi, IntechOpen, DOI: 10.5772/intechopen.71217. Available from: https:// www.intechopen.com/books/natural-killer-cells/nk-cells-in-cancer-immunotherapy
- University of Central Florida. (2018). Natural killer cells may open lifesaving cancer treatments to more patients. Science Daily. Available from www.sciencedaily.com/releases/ 2018/10/181002114010.htm IMC
- FDA clears IND application for natural killer cell-based COVID-19 therapy (April 2, 2020). Retrieved from https://www.healio.com/hematology-oncology/cell-therapy/news/online/%7B90e365e2-5579-4643-976c- cbb17ff5ff16%7D/fda-clears-ind-application-for-natural-killer-cell-based-covid-19-therapy