How does your immune system protect you?

The immune system has a vital role in defending the body from harmful substances, germs, and thus infections. It is made up of a complex network of cells, chemicals, tissues, and organs that recognize invaders and mount an immune response to help the body fight the invasion. It recognizes invaders such as bacteria, viruses, and fungi as well as abnormal cells. Thanks to the immunological memory, some ‘germs will only make you ill the first time you encounter them, with childhood diseases like chickenpox representing an example (1).

Tasks of the immune system

The immune system helps our body fight harmful foreign and self-substances. The main tasks of the body’s immune system are

1. Fight disease-causing pathogens

The term pathogens refer to the various bacteria, viruses, and fungi that encounter our body every day and are harmful to it. Therefore, the body needs a protective system to prevent us from getting sick constantly.

2. Recognizing and neutralizing harmful substances

An efficient and healthy immune system will detect the foreign substances that pose a risk of harm and neutralize them. The immune system does this by recognizing and responding to substances known as antigens.

3. Fight disease-causing changes in the body

One of the primary functions of our immune system is to maintain a healthy dynamic of cell death and cell regeneration. Some changes that can take place in the body and lead to disease development are cells that proliferate malignantly causing cancer.

The healthier the immune system, the stronger it is to mount a defense response. Therefore, it is important to maintain a healthy diet and lifestyle habits to support our immune system and enable it to fend off whatever bacteria or virus may come its way (2,3).

How is the immune system activated?

The immune system is activated by antigens that are not recognized by the body as its own. The antigens are recognized by special receptors expressed on the immune cells and this antigen-receptor interaction gives rise to a series of processes that are involved in mounting an immune response. Our immune system also has a memory to store information about the antigen it has encountered previously and mount an even stronger response after a second exposure to the same antigen. Sometimes the immune system mistakenly attacks healthy and harmless self–substances giving rise to an autoimmune response (4).



2. Chaplin DD. Overview of the immune response. J Allergy Clin Immunol. 2010 Feb;125(2 Suppl 2):S3-23. doi: 10.1016/j.jaci.2009.12.980. PMID: 20176265; PMCID: PMC2923430.

3. Zhang Y, Liang C. Innate recognition of microbial-derived signals in immunity and inflammation. Sci China Life Sci. 2016 Dec;59(12):1210-1217. doi: 10.1007/s11427-016-0325-6. Epub 2016 Nov 23. PMID: 27888386.

4. Rossi A. Understanding the immune system. Posit Aware. 1998 Nov-Dec;9(6):28. PMID: 11366476.