What is the immune system

What Is The Immune System?

Written by: Swisse Wellness
Swisse Wellness

We’re hearing a lot about the immune system at the moment, but what exactly is it and how does it work? Here’s a simple explanation of some of the components of immune system.

What is the function of the immune system? (1)(2)

One of the first lines of defence, the immune system is made up of different types of immune cells, organs, and chemicals that all play a role in protecting us from harmful microbes. Even our skin and gut form part of our immune system.

Immune system explained: some important components

White blood cells

White blood cells are the key cells of the immune system responsible for fighting viruses, bacteria and other foreign invaders that threaten your health. White blood cells, which are made in bone marrow and stored in blood and lymph tissue, include lymphocytes and other immune cells (3). White blood cells are essentially the immune system’s ‘front line’(4). While they only account for 1% of your blood, they have a huge impact in protecting you from disease and infection(3).

How do white blood cells fight infection?

White blood cells circulate around the body looking for potential threats, like bacteria and viruses. When they locate a threat, they alert other white blood cells, which rush to the site to help defend the body from attack. This white blood cell army produces antibody proteins which attach to the foreign organism and destroy it(5).


Antibodies are important in identifying potentially harmful foreign substances such as pathogens and toxins (antigens) and marking them for “destruction” by phagocytic cells. When the immune system detects antigens it responds by producing antibodies or cells that directly attack the pathogen.

The lymphatic system

The lymphatic system is a network of vessels, lymph nodes and white blood cells. Its main role is to keep body fluid levels in balance and defend the body against infections and harmful bacteria and viruses.

Is the immune and lymphatic system the same?

The lymphatic system and the immune system are not quite the same. The lymphatic system is considered an informal part of the immune system and is important to its functioning(6). The full extent of the lymphatic system’s role in immunity is still being explored, but there is no doubt that it is a critical component(6).

How does your immune system work? (7)(3)

The immune system is activated when the body recognises something that is not meant to be there. When this happens, the immune cells attach to the foreign matter and work together to destroy it.

Once our immune system encounters a pathogen for the first time, it stores information about it and how to fight it. This way, if we come into contact with it again, our immune system will know how to efficiently fight it straight away.

Your immune system is always learning and adapting and is therefore also able to fight bacteria and viruses that change over time.

This is how vaccines work; they introduce antigens to our body which trigger the body’s immune response without causing illness expose your body to a small amount of a antigens so that our body is able to recognise it and fight it quickly if it is exposed to it in the future.

It’s also important to remember that overall nutrition status and pattern of food intake (comprised of foods, nutrients and non-nutritive bioactive compounds) impact the functioning of the immune system(8).

Why do we need an immune system? (9)

We are continuously exposed to potentially harmful foreign substances (for example by inhaling, swallowing or through the skin). Whether or not these substances make us unwell depends on what the substance is, how harmful it is to our body and the ability of our immune system to defend the body from the substance.

How does the gut play a role in immune health?

The human gut is home to billions of bacteria (known as the gut microbiota) which play a fundamental role in our immune system. The gut microbiota protects against foreign microorganisms by its barrier effect. In return, our bodies provide the microbiota with food and nutrients so that a delicate balance is at play(10). Disruption to this balance can be caused by medications such as antibiotics, dietary patterns or disease states(11) but this is still the topic of much scientific research.

How do you improve your immune health?

  • Healthy immune system warriors need good, regular nourishment so make sure your diet includes immune-boasting nutrients such as zinc, selenium, iron, copper, magnesium, folic acid, and vitamins A, B6, C & D.
  • Your overall nutrition status, state of nourishment, and pattern of food intake (comprised of foods, nutrients and non-nutritive bioactive compounds) impact the functioning of the immune system.
  • Take care of your gut health as the gut can be an entry point to pathogens: Gut microbiota works with the immune system to maintain our health.
  • Keep active: Exercise can support the immune system by reducing inflammation in the body.
  • The stress response is the body’s way of protecting you but stress may weaken the response of your immune system and trigger inflammatory activity. It is important to minimize stress to support the natural immune response.
  • Getting enough sleep is important. During sleep, your immune system releases proteins called cytokines which are essential for regulating immune responses.



  1. Immune system. Betterhealth.vic.gov.au. (2020). Retrieved 31 March 2020, from https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/immune-system.
  2. Immune system. Healthdirect.gov.au. (2020). Retrieved 31 March 2020, from https://www.healthdirect.gov.au/immune-system.
  3. University of Rochester Medical Centre. What Are White Blood Cells? https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentID=35&ContentTypeID=160 Retrieved 24 July 2023
  4. University of Michigan, Michigan Medicine. Understanding White Blood Cells’ Defense Mechanisms Could Lead to Better Treatments. https://www.michiganmedicine.org/health-lab/understanding-white-blood-cells-defense-mechanisms-could-lead-better-treatments Retrieved 2 August 2023.
  5. Tigner A, Ibrahim SA, Murray IV. Histology, White Blood Cell. In: StatPearls. Treasure Island (FL): StatPearls Publishing; November 14, 2022.
  6. Randolph GJ, Ivanov S, Zinselmeyer BH, Scallan JP. The Lymphatic System: Integral Roles in Immunity. Annu Rev Immunol. 2017;35:31-52. doi:10.1146/annurev-immunol-041015-055354
  7. InformedHealth.org [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-. How does the immune system work? [Updated 2020 Apr 23]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK279364/
  8. Parkin J, Cohen B. An overview of the immune system. Lancet. 2001;357(9270):1777-1789. doi:10.1016/S0140-6736(00)04904-7
  9. Venter C, Eyerich S, Sarin T, Klatt KC. Nutrition and the Immune System: A Complicated Tango. Nutrients. 2020; 12(3):818. https://doi.org/10.3390/nu12030818
  10. Kamada N, Seo SU, Chen GY, Núñez G. Role of the gut microbiota in immunity and inflammatory disease. Nat Rev Immunol. 2013;13(5):321-335. doi:10.1038/nri3430
  11. McBurney MI, Davis C, Fraser CM, et al. Establishing What Constitutes a Healthy Human Gut Microbiome: State of the Science, Regulatory Considerations, and Future Directions. J Nutr. 2019;149(11):1882-1895. doi:10.1093/jn/nxz154
Swisse Wellness

Swisse Wellness - Swisse Wellness

The copywriting team at Swisse Wellness plan, research and generate blog content with inputs from multiple teams across the business. With access to our industry-leading Science team, Product Development team, Customer Service team as well as informative Brand Managers, we have the contacts to deliver a well-rounded suite of blogs tailored to an array of wellness interests....