An Overview Of The Immune Response

The immune response is an essential mechanism of the human body and we use it to protect ourselves from external factors that can be harmful to our health. It also consists of various processes and cells. Today we tell you everything you need to know about it.

Overview of the immune response

The immune response is the series of phenomena that the body performs to recognize and eliminate external agents that it perceives as harmful. These phenomena are based on the recognition of these foreign substances, also called antigens.

Antigens are usually found on the surface of viruses, bacteria, and fungi. Similarly, they are contained in other inert substances such as chemicals. Other different materials or toxins can also be antigens. Humans have two different types of immunity. Today we are going to tell you what each of them is about.

Innate Immunity

Innate immunity is not specific. It is already present before it comes into contact with a particular antigen and as the name suggests, all humans are born with it. We can divide this type of immune response into two different mechanisms:

• Barriers can be physical, such as the skin that prevents the passage of the substance in the body or a chemical. There are many chemical barriers in the human body. Runny nose, tears, saliva or vaginal discharge for example. These substances have properties that make it difficult for a virus or bacterium to survive. We can cite the pH of vaginal discharge (Spanish link) as an example, most pathogens cannot survive there.

• Cellular mechanisms consisting of the complement system, the inflammatory mechanism and phagocytes. The basis of all three mechanisms are substances that are present in the blood and continuously circulate in the blood vessels. These systems become active in eliminating foreign substances that enter the body.

Specific types of immunity

This is the second type of immune response. Unlike the innate response, we are not born with a developed specific immunity. It takes shape when the body comes into contact with different antigens. It becomes faster and more effective in eliminating pathogens.

The tissue responsible for this type of immunity is the lymphatic tissue, consisting of organs such as the spleen or thymus, and lymphatic vessels. This tissue houses the production of lymphocytes, which are the cells responsible for carrying out this type of immune response.

For example, specific parts of the antigens, called epitopes (Spanish link), recognize the newly invading antigens. Innate immunity is activated more quickly when one of them enters the body, but it is less effective. Similarly, the adaptive version is slower, but much more effective.

A lymphocyte will recognize the epitope of an antigen. You may not know it, but lymphocytes are responsible for producing substances called antibodies, which are responsible for eliminating the pathogen.

In addition, this lymphocyte will activate more lymphocytes that will come to the site to remove the antigen. This is the primary specific immune response.

Apart from the primary immune response, there is also a production of memory lymphocytes. These memory lymphocytes will elicit specific immunity when they come into contact with the same type of antigen. They are activated even faster to eliminate the harmful substance. This is known as a secondary immune response.

Passive and Active Immunity

Active immunity has everything to do with the complex we mentioned above. The human body naturally does it when it comes into contact with an antigen. The innate immune response is activated first, then the primary specific and finally and in case of successive contacts, the secondary immune response.

In addition, specific antibodies already circulate in the body without having been in contact with antigens in passive immunity. This can only happen in two cases:

• In newborn babies, via antibodies that a mother passes on to her baby during her pregnancy.
• In vaccinated people, because vaccines can consist of antibodies or fragments of the pathogen that trigger the production of memory lymphocytes without actually causing the disease.

The immune response is an immune system

Immunity is a natural defense system of the body and there are many ways to take care of it and maintain it. We have to be up to date with vaccinations and also do everything we can to keep our immune system in good shape.