Immune system – the primary defense mechanism

Immune system – the primary defense mechanism

The immune system is a complex biological system. In fact, after the human brain, it’s even the second most complex system. It constantly protects the body against infections and diseases. That’s why it’s important to understand how it works and why to take good care of it.

How does the immune system work?

The immune system is the primary defense mechanism that constantly protects the body against viruses and bacteria, especially during the cold and flu season. That's why it's essential to give the immune system the care it needs – so that, in return, it can take care of the body. The immune system is incredibly complicated and utterly vital for survival. Several different systems and cell types work in perfect synchrony throughout the body. Immune organs, tissues, cells, and molecules are interconnected to fight off pathogens and clear up dead cells. External threats include germs such as bacteria, viruses, fungi, and toxins. If the immune system is doing its job correctly and runs smoothly, we don't even notice it's there. However, if the immune system is compromised due to deficiency or an aggressive form of bacteria or virus, the body reacts with illness.

The immune system is activated immediately once an unknown intruder – also known as antigens – is in the body, and a series of processes are triggered. The so-called B lymphocytes make antibodies, and these proteins lock onto the antigens, to mark them. Other cells, such as the phagocytes, remove or inactivate the unknown intruders. After the immune system successfully has terminated the antigens, the body usually stores information about the intruder/antigen – how to recognize it later again and fight it faster.

The main parts of the immune system are:

  • White blood cells

    White blood cells are front and center when it comes to immune response. These cells are made in the bone marrow as part of the lymphatic system, and they look for foreign intruders and launch an immune response.

  • Antibodies

    Antibodies help fight microbes and the toxins by recognizing antigens and marking them for destruction.

  • Complement system

    The complement system consists of various proteins that help the antibodies complete their task.

  • Lymphatic system

    The lymphatic system also plays a vital role. As a network of delicate tubes throughout the body, it manages fluid levels, reacts to bacteria in the body, and deals with cancer cells and cell products that could lead to disease or disorders. The lymphatic system consists of lymph nodes, lymph vessels, and white blood cells (lymphocytes).

  • Spleen

    The spleen removes microbes and destroys old or damaged red blood cells. As a blood-filtering organ, it also makes disease-fighting components of the immune system.

  • Bone marrow

    Bone marrow is the spongy tissue inside the bones, which produces the oxygen-carrying red blood cells, the infection-fighting white blood cells, and the blood-clotting platelets.

  • Thymus

    The thymus filters and monitors blood and produces white blood cells (T-lymphocytes).

Two different immune responses

The immune system consists of immune organs, tissues, cells, and molecules that are interconnected to fight off external or internal threats. There are two main types of immune responses: innate immunity and adaptive immunity, and both are essential for health and survival:

The innate immune system

Humans and animals are born with the innate immune system. Its primary purpose is to prevent the spread of harmful agents by attacking them with cells such as scavenger cells called phagocytes (or macrophages) and releasing numerous molecules (e.g., signaling molecules, antiviral compounds) that further assist and regulate the innate immune response. The innate immune system is the first to respond when it finds an invader. The line of defense includes the skin, the eye's cornea, and the mucous membrane that lines the respiratory, gastrointestinal, and genitourinary tracts. These physical barriers protect the body against harmful germs, parasites, or cells (such as cancer). If the pathogen manages to pass the innate immune system, the adaptive immunity kicks in.

The adaptive immune system

The adaptive immune system develops during its lifetime in response to exposure to infections and toxins. Together with the innate system, it produces unique proteins (called antibodies) to recognize and kill harmful agents with which the body has previously come into contact. These antibodies are made by B lymphocytes cells after the body has been exposed to the intruder. The adaptive immune system is constantly learning and adapting, and therefore, the body can also fight bacteria or viruses that change over time. It builds up a library of antibodies to different pathogens, sometimes called immunological memory.

Both immune responses are interconnected and play a critical role in defense against infections.

The effects of a strong immune system

The immune system is a highly complex network of organs, cells, and molecules that researchers are still working to understand. However, the reasons for having a strong immune system speak for themselves.

Fewer sick days

The first and most obvious benefit of having a strong immune system is being less susceptible to viruses and bacteria because the body fights them off effectively. This, in return, means fewer sick days.

Less medication

Especially during the flu season, most people tend to take synthetic medication to fight off colds. But unlike natural medicine, synthetic medications are often accompanied by various side effects. 

Milder symptoms

A strong immune response in the early stages of a cold or flu-like infection can reduce the illness's length and the severity of its symptoms.

Better for the body

Both the innate and the adaptive immune responses need to be well balanced. An effective immune system relies on a regulated immune response to successfully eliminate viral infections without harming the body.

How to strengthen the immune system?

For the immune system to work correctly, it needs to rely on balance and harmony. Researchers are still exploring the intricacies of the immune response and what exactly may strengthen it. At the moment, there is no scientific evidence that shows what positive effects lifestyle has on the immune function. However, healthy-living strategies such as diet, exercise, meditation, or stress management have proven health benefits, and overall good health has positive effects on the immune response system.


    Regular exercise improves cardiovascular health, lowers blood pressure, helps control body weight, and protects against various diseases. In other words, it contributes directly to general good health and therefore to a healthy immune system.


    A part of a healthy lifestyle is refraining from certain things. Excessive alcohol consumption, for example, can have numerous adverse effects on the body. The same goes for smoking, which weakens the immune system, making the body more susceptible to bacterial and viral infections.


    Stress can be good, but if the body has no time to recuperate and the strain continues, stress can even suppress the immune system, increasing susceptibility to colds and other illnesses.


    Poor nutrition can have a negative effect on the immune system. Therefore, a balanced diet is good for the body, and it includes fruits and vegetables that are rich in vitamins and minerals. Primarily, Vitamin C, Vitamin B6, and Vitamin E are known for their health-promoting effects.


    The body needs sleep to fight off infectious diseases, and sleep deprivation reduces the production of infection-fighting antibodies and cells. And in addition, long-term lack of sleep increases the risk of obesity, diabetes, and cardiovascular disease.

Pharmacological approach

In terms of boosting the immune system, pharmacological treatments are rare and not the common choice. Immunotherapy, for example, is a type of cancer treatment that helps boost the immune system’s response to cancer cells. Other synthetic medications are prescribed when viruses or bacteria weaken the immune system. Most mild viral respiratory illnesses are managed symptomatically with these medications but not to boost the immune system. Some healthcare providers may recommend vitamins and supplements to boost the immune system. Vitamin C, B6, and E are the most common. However, these vitamins are already available in a healthy diet. And some supplements may cause side effects, especially when taking them in combination with other medicines. The effects of many supplements haven’t been tested in children, pregnant women, and other groups.

Natural medicine approach

Several other non-prescription plant-based medications are used for fighting off viral infections and the common cold, not just for treatment but also for prevention. The most common natural ingredient is Echinacea, also known as the coneflower. Several studies have provided some positive results in effectiveness; however, at the same time, other clinical trials reported no effect compared with placebo. Since the data are conflicting in some areas and there is a lack of consistency concerning the Echinacea species, organs, and preparations used in each study, comparisons between trials are complicated.8-10 

Other natural ingredients such as Swallowwort and Sulfur, especially in combination, affect the immune system by enhancing and supporting the body’s endogenous defense mechanisms. Studies have shown that certain natural medications with these ingredients stimulate the immune system to produce antiviral compounds, known as interferons which play a significant role in regulating immune responses.11

Heel natural medicines







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