This is how the specific & non-specific immune defense works: acquired and innate immune system explained simply

Simple definition: the specific and non-specific defense of the immune system

The non-specific defense is a part of our body's immune response and is present from the beginning. This means that the non-specific immune system is already functioning at birth and is also referred to as the innate immune system. It sounds the alarm as soon as our body comes into contact with pathogens such as viruses and bacteria, and includes the first defense mechanisms of our body¹.

The specific defense only develops over the course of our lives. That's why it is also called the acquired or adaptive immune system. This only kicks in when the innate immune defense has failed. At this point, the pathogens have already entered our body.

What is the difference between non-specific and specific defense?

There are several differences between the non-specific and specific defense mechanisms. The timing at which each part of the immune response forms is crucial for its function. The non-specific immune response recognizes and eliminates foreign substances, regardless of whether our body has already come into contact with the pathogen. It is a kind of general defense mechanism.

Our acquired (adaptive) immune system must first develop and continues to evolve throughout life. It is the specific part of our defence system that responds to certain pathogens. What makes it special is that the specific defence adapts, recognises the intruder and stores it in what is known as immunological memory.

What is the non-specific immune response exactly and how does it work?

At the non-specific defense, as the name suggests, the non-specific immune system defends against foreign substances in the body. This means that the non-specific immune system is not specialized in specific pathogens. For example, it cannot recognize and neutralize a virus that causes measles. Instead, all pathogens are fought in the same way.

For example, the skin and the small cilia of the mucous membranes take on the defense function. The first physical or chemical barriers also include the acid mantle of the skin, stomach acid, saliva, and our tears. All these barriers are intended to prevent bacteria, viruses, and others from entering the body on one hand, and on the other hand from establishing themselves there. Fever is a non-specific defense reaction of the body. This is an innate defense mechanism that tries to fight bacteria and viruses by using heat.

If these defense mechanisms are not sufficient and pathogens enter our body, special proteins and defense cells take over. These cells are mainly white blood cells (phagocytes), which literally devour the pathogens. Natural killer cells also belong to the non-specific immune defense, which can target infected cells.

To the non-specific immune cells include the following white blood cells:

• Granulocytes

• Monocytes

• Macrophages

• Dendritic Cells

• Mast cells

• Natural killer cells

With the exception of mast cells and natural killer cells, all are phagocytes (also known as scavenger cells). These cells almost completely engulf the pathogen, only a small part attaches to their surface and can thus be recognized by the specific immune system as such.

The non-specific humoral immune response - A brief explanation of the complement system

This type of defense mainly works through proteins that are dissolved in body fluids. These proteins can bind to pathogens and become activated. By triggering an inflammation, the defense cells can better reach the site of infection. They also attract phagocytes, which promptly fulfill their task. Additionally, the proteins can attach to pathogens and mark them, making them easier to be recognized by the phagocytes. The proteins always alert more proteins, creating a kind of chain reaction and rapidly strengthening the immune system.

There is not only the distinction between acquired and innate immune system, but also in cellular and humoral. The cellular part is responsible for already infected cells and is carried out by cells, while the humoral immune response works through antibodies.

What is the specific immune response and how does it work?

Children are more susceptible to infections because they lack the acquired immunity that adults have developed over the course of their lives. But you can also strengthen children's immune system. Because our specific immune system is something like the secret weapon of the immune system and takes over when the pathogens have managed to penetrate the barriers and spread in our body. The pathogens first reach the lymphoid organs, such as the lymph nodes or the thymus. There, the lymphocytes (T and B lymphocytes, natural killer cells) are already waiting, which attach to the appropriate antigens. Parts of acquired immunity are:

• T-lymphocytes: These are also called T cells and activate B lymphocytes, phagocytes, and other immune cells. T cells have various functions, but the most important one is: they initiate the specific defense mechanism.

• B-lymphocytes: They transform into plasma cells after being activated by a T cell, which produce a variety of antibodies. A portion of the activated cells transform into so-called memory cells.

• Antibodies: Antibodies are produced by the immune system to neutralize pathogens. They bind to antigens (specific surface structures) according to the so-called lock-and-key principle.

The reason why the specific immune response is considered the secret weapon of our immune system lies mainly in the memory cells. These store information about harmful intruders so that our body can react much faster the second time - not within a few days or weeks, but rather hours. One develops a certain immunity and because our immune system keeps learning more, we become immune to more and more pathogens. Nevertheless, it is important to support our immune system.

How can one support the specific and non-specific immune defense?

Our immune system is busy around the clock. Even the smallest cut is enough to put our body's defense system on high alert. That's why it's important that we strengthen our immune system. This can be achieved, for example, through sufficient sleep, a healthy diet with plenty of vitamins for the immune system, lots of exercise, and less stress. But all of this is not only good for our immune system, but also for ourselves.