What is acquired immunity?

The immune system is the best ally when it comes to dealing with diseases. This is composed of an innate component and an acquired one. Do you know how acquired immunity works?

The immune system, both innate and acquired, is essential for optimal health. But what does acquired immunity consist of? How is it strengthened over time? Resolving these doubts is essential to enjoy a routine without diseases. This time we want to detail more about it.

Symptoms such as ongoing colds, recurrent fevers, and repeated bacterial infections can be indicative of a weakened immune system. According to the American Academy of Allergy, Asthma and Immunology, more than three episodes of bacterial sinusitis or more than two antibiotic treatments annually, denote immune problems.

About biological barriers

The human body presents containment barriers beyond the immune system. These are divided into three types:

  • Primary barriers: according to various studies, the skin is the first containment barrier against possible pathogens. Lipids and keratin are elements in its composition that make the epidermis a true retaining wall against viruses and bacteria.
  • Secondary barriers: once the primary mechanisms fail, neutrophils and macrophages (white blood cells) are in charge of enveloping and destroying pathogens. This is known as phagocytosis, and it is a clear example of a secondary barrier.
  • Tertiary barriers: Many structures produced by pathogens are recognized by T and B lymphocytes, which effectively inactivate or destroy them.

This distinction of biological barriers is essential, since it allows us to understand that when we speak of the acquired immune system we are dealing with a tertiary biological barrier.

What is acquired immunity?

Thus, the acquired immunity system is defined as a set of highly specialized cells and systemic processes that eliminate or avoid pathogenic threats. According to  immunological research, this system is unique to vertebrates.

Its function is to recognize germs in a specific way to be able to fight them more effectively and quickly. Although it may seem surprising, it can be said that this biological barrier has a memory, since the response to the same pathogen is increasingly powerful.

What elements compose it?

The effectors of this protection system are T lymphocytes and B lymphocytes (blood leukocytes), which are produced in the thymus and bone marrow, respectively.

The acquired immune system cannot be understood without the innate one, since as indicated by various sources, it is the cells of the innate system that process antigens (viral and bacterial substances) and present them to the lymphocytes so that they act accordingly.

In order not to complicate things too much, we will limit the importance of lymphocytes to the following:

  • Each type of lymphocyte has a receptor for each antigen presented by the pathogen.
  • This information is replicated in each new generation of these cells and generates an even more effective defense system against each wave of infection.

Symptoms of a weakened immunity

As we have advanced at the beginning, there are various signs that trigger suspicion when the acquired immune system is not working as it should. Some of them are the following:

  • More than two antibiotic treatments a year.
  • More than four ear infections annually.
  • Development of two pneumonia in close periods of time.
  • Three or more episodes of chronic sinusitis annually.
  • Need for preventive antibiotics to reduce the risk of infections.
  • Development of serious infections from common bacterial pathologies.

When meeting these requirements, it is essential that the patient goes for a medical check-up immediately. The results will be treated by an immunologist, who will diagnose the underlying reason for the immunosuppression.

How to strengthen the acquired immune system?

As we have seen, the most effective way to strengthen this tertiary barrier is none other than exposure to pathogens. This does not mean that we seek to get sick, because vaccines were devised precisely for this purpose.

According to the World Health Organization (WHO)vaccines are preparations with weakened or dead forms of harmful microorganisms, which promote the stimulation of antibodies (receptors for the aforementioned lymphocytes) when introduced into the human body.

The acquired immune system responds to these stimuli, since it destroys and remembers the possible threats present in vaccines, although these do not pose a real harm to the patient. Thus, when the actual pathogen is present, the lymphocytes will recognize it immediately before an infection occurs.

What to remember about acquired immunity?

Acquired immunity is an extremely important tertiary biological barrier, since it repeatedly protects humans from an infinity of pathogens. Therefore, it is essential to learn about the vaccination schedules in each country and region, and to follow them strictly.

Vaccines not only protect us by encouraging the specialization of the acquired immune system, but also generate a herd immunity that protects the weakest and sickest.

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