¿Cómo funciona nuestro sistema inmunológico?
White blood cells seen under a microscope. (Photo: iStock)

In H. G. Wells’ War of the Worlds, humans use a secret weapon to defeat the beings from another planet who seek to eradicate them: their immune system, developed over millions of years.

Our immune system is with us from birth and helps us cope with the world around us. Even when we are at an embryonic stage, our innate defenses are beginning to develop. As we grow, there are factors that work against it and prevent it from mounting an adequate defense.

How do we define it?

The immune system runs throughout our bodies. It is made up of tissues, cells, and molecules in the blood. Its activity defines our individuality because it is capable of differentiating between what is our own and what is foreign, like viruses or bacteria.

This ability defends the body because it allows it to recognize the particular characteristics of each pathogen, characteristics that are called antigens, and which the immune system tries to destroy.

The key cells within the immune system are lymphocytes, while important specific proteins are called antibodies. The primary lymphoid organs are the red bone marrow and the thymus, while lymph nodes are the secondary organs.

Your immune system is unique and matures throughout your body’s life, as it acquires and develops an immune memory. One part of that memory is ancestral.

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Innate and acquired

“Innate immunity comes from the barriers that prevent harmful materials from entering the body. Coughing, tears, skin, gastric acid in our stomach, and hairs in the nose are an important part of this innate immunity,” shares the endocrinologist Jorge Yamamoto.

Yamamoto says that both before and after birth, we begin to gain an acquired immunity: when our mother shares antibodies with us in the womb and then through breast milk. This strengthens our immune system’s ability to respond to infections. This is known as active immunity and is our body’s response to viruses or bacteria.

Thanks to scientific breakthroughs, from birth onwards we also have access to another type of support for our immune system. This is artificial active immunity, which comes in the form of vaccines that help to keep us healthy.

An ally against diseases

Vaccination is one way to strengthen our immune system. “If you don’t get vaccinated and you get measles, it’s extremely serious. If you get vaccinated and you get it, you’ll only get three or four blotches. The difference is in the immune response: the way you’ve trained your body to defend itself,” Yamamoto points out.


Other allies of your immune system include:

Doing exercise


A balanced diet

Only taking vitamins prescribed by a doctor

Just as you can improve and maintain an adequate defense system, there are also factors which prevent our bodies from responding to infections.

Enemies of the immune system

Chronic stress is one of biggest enemies of your immune system. And it is different for each person. It can start out as pre-depression and then get worse.

“It’s been proven that lack of sleep and chronic stress can alter the immune system’s response”, says Alejandro Garza Alpirez, a specialist in Immunology and Rheumatology from the Institute of Internal Medicine at TecSalud’s Zambrano Hellion Hospital.

This situation is complicated because stress can be caused by different individual situations. “We generally see it in people with generalized anxiety or depressive disorders. But it doesn’t have to be depression; it could be dysthymia,” adds the specialist.

Treating chronic stress will prevent a lowering of the body’s defenses. “Any general practitioner, family doctor, or internist will notice this. Stress has different triggers. For one person, it might be having a very strict boss; for someone else, it might be her husband not getting home at eight o’clock in the evening,” explains Garza.

Other factors that weaken the immune system are being overweight or obese, because they are both inflammatory states. The body’s defenses work by mounting an inflammatory response, so people in these conditions can have an “overreaction”.

Alcoholic beverages in excess can also alter the immune system. A lack of physical activity is another factor in having a low immune response.

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Defenses against Covid-19

As the body has its own mechanism for defending itself against external threats, overreaction can complicate relief. This is one of the situations we see with a new virus like the one that causes SARS-CoV-2.

“Imagine the immune system as an army that must defend the president. The defense cells are the soldiers that will defend you. If the soldiers use nuclear bombs against the attacker, they’re going to take out the president in the process,” says Garza.

This means that the consequences of the body’s overreaction can cause death. Unfortunately, there is no way to avoid an overreaction, as it depends on the individual patient.

“There’s no medicine that you can prescribe the patient, there are no herbs, there are no balms. There’s nothing anyone can do to prevent this overreaction of the immune system,” says the TecSalud specialist.

However, factors such as having a restful sleep routine, exercising, keeping a balanced diet, avoiding being overweight, and moderating alcohol intake are a good start.

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