The Never-Ending Battle: A Guide to the Immune System
- Rohan Naidoo
- 23 hours ago
- 9 min read
The immune system is our army, waging war against the particles that threaten illness & disease. The immune system is a highly organised department, that deals with foreign information as it enters our bodies. The immune system is like a coat, a wooly fleece that promotes comfort & wellbeing within our own bodies. However, when will that coat start to give us an itch? When will it start to chafe on our skin? When will it seem as if this innate coat of ours has turned on us & starts to serve as a burden. As complex as it may seem, the immune system is an overarching & interconnected bodily function that works with, is present within & complements other systems of our body. While it may be difficult to understand the workings of immunity, how it manages to protect & complement our bodily functions, why we still feel sick if we have a strong immune system & why one can still contract a secondary infection from illnesses, this article aims to provide you with the necessary tools to not only understand the workings of this magnificent facet of the body, but to place it into practice when you next notice your immune system at work.
It all starts in the bone marrow, where stem cells produce blood cells that will go on to differentiate & perform different functions for the body. One of these cells formed are the leucocytes. The leucocytes are the foundation for immunity, which produce even more specialised cells to tailor specific responses to foreign particles.
Consider the table below:
As shown by the table above, we can see that leucocytes can be divided & categorised by their functions. Granulocytes & monocytes are phagocytic, that is they "engulf" foreign particles. The B-cells make antibodies, proteins that counteract the foreign particles [antigens], while Killer T-cells help burst infected cells to prevent further infection. Suppressor T-cells stop the immune reaction, while Helper T-cells control the entire action of all the T & B-cells.
It would be silly to not give a glimpse into the interconnectedness of the entire body & how it helps boost the function of the immune system & vice versa. The nasal cavity with its turbinate bones plays a crucial role in filtering the air we breathe, preventing our bodies from contracting illness. The tonsils & adenoids help further trap antigens before they enter the body. This could be said the same for the mucosa, the tissue lining organs & surfaces in the body that secretes mucus to trap foreign particles & dispose of them out of the body.
These basic parts all work together to produce a highly systematic & functional immune system, that can be categorised into the innate & adaptive immune responses. The skin is the first line of defense, the phagocytic granulocytes & macrophages engulfing antigens if it makes it past this first line of defense. This responsive is relatively quick, & is the same for all antigens that enter the body. This is the innate defense system at play. The macrophages present a little bit of the antigen on their surface, allowing for T-helper cells with matching receptors to the antigen, to rapidly clone & become active T-helper cells. A small portion of these cells instead become Memory Helper T-cells. Keep this in mind for later. These activated cells release small proteins - cytokines, that stimulate two contrasting & equally important responses: the humoral immune response & the cell mediated immune response. In both cases, cytokines stimulate certain cells which then rapidly clone themselves to form memory cells & activated cells that each complement the immune systems with different stances. The humoral response stimulates B-cells that produce antibodies, proteins that mount a chemical attack on the antigen. The cell mediated response ignites the action of killer T-cells, which lyse [burst] infected cells, allowing for the antigen to be exposed to the phagocytes wandering about in our blood plasma, lymphatic system & other tissues.
By having a simple framework to prevent antigens from being contracted, & with unforgiving phagocytes, the immune system is further layered with antibodies & killer T-cells to provide a well-rounded & sufficient immune system for the body. It is useful to know that antigens stimulate certain T & B-cells, which then tailor different antibodies to counter the antigen more effectively. The memory cells produced ensure that if you ever contract the same illness, your immune system can kick straight into gear & rid of the pathogen in no time.
"How Do I Know My Immune System is Working Properly?"
Now having understood the basics, we can see how the immune response can manifest in our daily & physical lives. The release of cytokines by T-helper cells & macrophages, act as a chemical for communication, increasing blood flow to a cut or infected area. This penetrates the capillary walls to a greater extent, leading to inflammation over infected or injured areas & a red-spotted appearance. How about when you're down with a cold? One of the common signs that the immune system is fighting off illness properly is when the lymph nodes become swollen. Ever wonder why a physician might place their fingers below your jaw? Finding swollen lymph nodes is a sign to your local physician that your body is fighting an illness, & perhaps quite sufficiently. "What about my fever?" Fevers are often the body's way of raising body temperature to reach an optimum temperature to fight off disease. The increased blood flow to an area, cytokines released by the macrophages & T-helper cells, as well as the bursting of cells by killer T-cells, all contribute towards raising one's body temperature, while still fighting off pathogens. Next time you are worried about a red area on your body when you scratch yourself in the outdoors, or when you find yourself coming down with a fever after a long night out with friends, know that it is your immune system's way of telling you it has got your back.
"Why Do I Still Feel Sick if I Have an Immune System?"
The answer is simple. As mentioned above, the signs of your immune system at play can cause you to feel unwell at times. Also, if you are exposed to a new virus or rapidly evolving one, your body will have to produce the antibodies to counteract the disease. The time before this happens, however, is where you might show some of the symptoms of the illness you would've contracted.
With this in mind, the immune system can produce some complications. Although equipped with suppressor T-cells, which stop the immune response, secondary infections can still occur after an initial infection. After contracting & fighting an illness, the immune system could be weakened, making the body more susceptible to contracting another illness. Another simple way to think of this, is because the body has been changed by a prior immune response. Breaks in the skin, or even excess amounts of mucous produced in the body to trap foreign particles, could lead to new illnesses, including infections like pneumonia.
The Immune System Turns on the Body
We spoke about how it can be considered good if you notice a red area over an injured wound, but to what extent would we consider all of these physical signs healthy. Persistent fevers, excessive fatigue, unexplained weight loss & fevers, numbness & inapt hair loss may be a sign of an immune problem. Here, I will briefly discuss three ways in which our immune system can seemingly turn its back to us & do more harm than good.
Hypersensitivity
Hypersensitivity can be considered one of the exceptions to the understanding of immunity. It is the increased sensitivity to a seemingly harmless antigen, to which it has been previously exposed. This gives way to the understanding of "allergies" as we know it today. Hypersensitivity can be classified into three groups, each increasing with harmful effect on the body. Type I Hypersensitivity is what most people with allergies would fall under, with Type 2 & 3 leading to tissue & bodily dysfunctions, damage & impairment. It is important to note, that this differs form autoimmunity & an immunodeficiency, as hypersensitivity relates to an overexaggerated response to antigens.
Autoimmune Diseases
A simple understanding of this states that the body, instead of attacking foreign, external antigens, attacks normal, healthy tissues & cells. This often manifests as Type 1 Diabetes, where the immune system destroys beta cells, cells producing insulin in the pancreas. Rheumatoid Arthritis entails the swelling & deformity of joints, as the immune system attacks the synovium- the tissue secreting fluid at joints for easy movement & lubrication. Lupus attacks perfectly healthy tissue from a number of varying tissues & organs, including the lungs, kidneys & skin.
Immunodeficiency Disorders
These disorders are characterised by a severely weak immune system, that makes the body prone to contracting illness, disease & infection. Primary immunodeficiency is gained genetically, while secondary immunodeficiency can be acquired through contracting a particular disease, like HIV.
Understanding HIV
Probably one of the most pressing & timeless matters in immunology over the past few decades, has been understanding the workings of HIV. While it has been around for ages, there is still no cure to it. This is simply due to the nature of this virus. The HIV virus is a retrovirus, meaning that its strands of information responsible for helping it reproduce in a host's body, are ribonucleic acids, or "RNA." Since these cells need to be converted to DNA to infect cells in the host by latching onto & controlling its DNA, RNA & retroviruses are quite unstable & can therefore evolve quite easily. The HIV virus also attacks crucial cells- our T-helper cells. Before the body can mount an immune response, the virus already destroys so many T-cells that it becomes a long road of fighting & recovering against the disease. HIV can weaken the immune system to such an extent, that the final stage of HIV is often diagnosed in-hand with AIDS.
The immune system is a fascinating & extraordinary facet of the human body. It is elaborate & categorised. It is specific & adaptive. However, as seen before, there is a fine line between what can be considered & seen to be a healthy immune response at work, before it becomes destructive, corrosive, or weak. Immunology has become a rising & increasingly more acknowledged branch of medical science, that provides insight into the human body, possibly allowing for new & innovative perspectives & discoveries to be made in other medical fields. The immune system is an example of the power & elaborate design of the human anatomy, showing how the body, no matter the system is interconnected in all it parts.
If you found this article interesting, & are fascinated in learning more about how the study of immunity is currently forging new groundbreaking discoveries across the medical world, consider reading the following:
Neuroimmune Interactions: From the Brain to the Immune System and Vice Versa
Scientists Discover New Part of the Immune System
Peacekeeper Cells Protect the Body from Autoimmunity During Infection
Lupus-Related Antibody Shows Promise in Enhancing Cancer Treatment Efficacy
The Immune Mind by Monty Lyman
Bibliography
Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K. and Walter, P. (2002). Innate Immunity. [online] Nih.gov. Available at: https://www.ncbi.nlm.nih.gov/books/NBK26846/.
Boskey, E. (2021). Secondary Infections Occur When a Primary Infection Goes Wrong. [online] Verywell Health. Available at: https://www.verywellhealth.com/what-is-a-secondary-infection-3132823.
Cleveland Clinic (2020). Immune System: Parts & Common Problems. [online] Cleveland Clinic. Available at: https://my.clevelandclinic.org/health/body/21196-immune-system.
Encyclopedia Britannica. (n.d.). Immune system - Macrophages. [online] Available at: https://www.britannica.com/science/immune-system/Macrophages.
John Hopkins Medicine (2019). Disorders of the Immune System. [online] John Hopkins Medicine. Available at: https://www.hopkinsmedicine.org/health/conditions-and-diseases/disorders-of-the-immune-system.
Lyman, M. (2024). The Immune Mind. Random House.
Marshall, J.S., Warrington, R., Watson, W. and Kim, H.L. (2018). An Introduction to Immunology and Immunopathology. Allergy, Asthma & Clinical Immunology, 14(S2). doi:https://doi.org/10.1186/s13223-018-0278-1.
Mayo Clinic (2023). Rheumatoid Arthritis - Symptoms and Causes. [online] Mayo Clinic. Available at: https://www.mayoclinic.org/diseases-conditions/rheumatoid-arthritis/symptoms-causes/syc-20353648.
Momtazmanesh, S. and Rezaei, N. (2020). Hypersensitivity. Reference Module in Biomedical Sciences, 1. doi:https://doi.org/10.1016/b978-0-12-818731-9.00032-x.
National Center for Biotechnology Information (2020). How Does the Immune System work? [online] National Library of Medicine. Available at: https://www.ncbi.nlm.nih.gov/books/NBK279364/.
Pfizer (2019). How the Immune System Protects You From Infection | Pfizer. [online] Pfizer.com. Available at: https://www.pfizer.com/news/articles/how_the_immune_system_protects_you_from_infection.
Wilshon , J. (2023). Immunology: Understanding the Complexities of the Immune System. International Journal of Clinical Rheumatology , [online] pp.99–101. Available at: https://www.openaccessjournals.com/articles/immunology-understanding-the-complexities-of-the-immune-system.pdf [Accessed 20 Mar. 2025].
World Health Organization (2024). HIV and AIDS. [online] World Health Organization. Available at: https://www.who.int/news-room/fact-sheets/detail/hiv-aids.
Wrotek, S. (2020). Let fever do its job. Evolution, Medicine, and Public Health, [online] 9(1). doi:https://doi.org/10.1093/emph/eoaa044.
www.sciencedirect.com. (n.d.). Human Immunodeficiency Virus - an overview | ScienceDirect Topics. [online] Available at: https://www.sciencedirect.com/topics/immunology-and-microbiology/human-immunodeficiency-virus.
Assessed and Endorsed by the MedReport Medical Review Board