- Immune system cells
- How it works
- Innate or natural immune response
- Adaptive or acquired immune response
- What are antigens and antibodies
- Types of immunization
- Active immunization
- Passive immunization
- How to strengthen the immune system
The immune system, or immune system, is a set of organs, tissues and cells responsible for combating invading microorganisms, thus preventing the development of diseases. In addition, it is responsible for promoting the balance of the organism from the coordinated response of cells and molecules produced in response to the pathogen.
The best way to strengthen the immune system and make it respond well to invading microorganisms is through eating and practicing healthy habits. In addition, it is important that vaccination is carried out, especially as a child, to stimulate the production of antibodies and prevent the child from developing diseases that can interfere with their development, such as polio, also called infantile paralysis, which can be prevented through the VIP vaccine. Know when to get the polio vaccine.
Immune system cells
The immune response is mediated by cells responsible for fighting infections, the leukocytes, which promote the health of the body and the person. Leukocytes can be divided into polymorphonuclear and mononuclear cells, each group having some types of defense cells in the body that perform distinct and complementary functions. The cells belonging to the immune system are:
- Lymphocytes, which are the cells that are normally more altered during infections, since it guarantees specificity to the immune response. There are three types of lymphocytes, B, T and Natural Killer (NK), which perform different functions; Monocytes, which are temporarily circulating in the blood and can be differentiated into macrophages, which are important for combating the organism's aggressive agent; Neutrophils, which circulate in higher concentrations and are the first to identify and act against infection; Eosinophils, which are normally circulating in smaller amounts in the blood, but have their concentration increased during allergic reactions or in case of parasitic, bacterial or fungal infections; Basophils, which also circulate in lower concentrations, but may increase due to allergies or prolonged inflammation.
From the moment that a foreign body and / or infectious agent enters the body, the cells of the immune system are activated and act in a coordinated manner in order to combat the offending agent. Learn more about leukocytes.
How it works
The immune system is responsible for protecting the body against any type of infection. Thus, when a microorganism invades the organism, the immune system is able to identify this pathogen and activate defense mechanisms in order to fight infection.
The immune system is composed of two main types of responses: the innate immune response, which is the body's first line of defense, and the adaptive immune response, which is more specific and is activated when the first response does not work or is not sufficient.
Innate or natural immune response
The natural or innate immune response is the organism's first line of defense, having been present in people since birth. As soon as the microorganism invades the organism, this line of defense is stimulated, being characterized by its speed and little specificity.
This type of immunity consists of:
- Physical barriers, which are the skin, hair and mucus, being responsible for preventing or delaying the entry of foreign bodies in the body; Physiological barriers, such as stomach acidity, body temperature and cytokines, which prevent the invading microorganism from developing in the body, in addition to promoting its elimination; Cellular barriers, which consists of cells considered as the first line of defense, which are neutrophils, macrophages and NK lymphocytes, responsible for encompassing the pathogen and promoting its destruction.
Due to the efficiency of the innate immune system, infections do not occur all the time, and microorganisms are quickly eliminated. However, when natural immunity is not sufficient to fight the pathogen, adaptive immunity is stimulated.
Adaptive or acquired immune response
The acquired or adaptive immunity, despite being the second line of defense of the organism, has great importance, since it is through it that memory cells are generated, preventing infections by the same microorganism from occurring or, if they do, become milder.
In addition to giving rise to memory cells, the adaptive immune response, although it takes longer to establish, is more specific, since it can identify specific characteristics of each microorganism and, thus, lead to the immune response.
This type of immunity is activated by contact with infectious agents and has two types:
- Humoral immunity, which is a response mediated by antibodies produced by type B lymphocytes; Cellular immunity, which is the immune response mediated by type T lymphocytes, which promote the destruction of the microorganism or the death of infected cells, since this type of immunity is developed when the pathogen survives innate and humoral immunity, becoming inaccessible to antibodies. Learn more about lymphocytes.
In addition to humoral and cellular immunity, the adaptive immune response can also be classified as active, when acquired through vaccination, for example, or passive, when it comes from another person, such as through breastfeeding, in which antibodies can be transmitted from mother to baby.
What are antigens and antibodies
In order for the immune system to respond, antigens and antibodies are needed. Antigens are substances capable of triggering an immune response, being specific for each microorganism, and that binds directly to the lymphocyte or an antibody to generate the immune response, which normally results in the destruction of the microorganism and, thus, an end to infection.
Antibodies are Y-shaped proteins responsible for protecting the body against infections, being produced in response to an invading microorganism. Antibodies, also called immunoglobulins, can be acquired through breastfeeding, which is the case for IgA, even during pregnancy, in the case of IgG, or be produced in response to an allergic reaction, in the case of IgE.
| Immunoglobulins | Characteristics |
| IgA | Protects the intestine, respiratory and urogenital tract from infections and can be obtained through breastfeeding, in which the antibody is transmitted from the mother to the baby |
| IgD | It is expressed together with IgM during the acute phase of infections, however its function is still unclear. |
| IgE | It is expressed during allergic reactions |
| IgM | It is produced in the acute phase of infection and is responsible for the activation of the complement system, which is a system formed by proteins responsible for facilitating the elimination of the invading microorganism |
| IG G | It is the most common type of antibody in plasma, it is considered the memory antibody and protects the newborn, as it can cross the placental barrier |
In response to infections, IgM is the antibody first produced. As the infection is established, the body starts to produce IgG which, in addition to fighting infection, remains in the circulation, being considered a memory antibody. Learn more about IgG and IgM.
Types of immunization
Immunization corresponds to the body's mechanism of promoting protection against certain microorganisms, which can be acquired naturally or artificially, as in the case of vaccines, for example.
Active immunization
Active immunization is one acquired through vaccination or due to contact with the agent of a particular disease, stimulating the immune system and causing it to produce antibodies.
Active immunization is capable of generating memory, that is, when the body comes into contact again with the agent that causes a certain disease, the body recognizes and fights the invading agent, preventing the person from developing the disease or having it more seriously.. Thus, this type of response is long-lasting, however it takes time for it to be established, that is, immediately after exposure to the harmful agent, there is no immediate formation of an appropriate immune response. The immune system takes time to process and assimilate this information.
Natural exposure to the pathogen is a way to obtain active immunization. In addition, it is important to obtain active immunization artificially, which is through vaccination, thus preventing future infections. In vaccination, the person is given the dead microorganism or its activity is reduced in order to stimulate the immune system to recognize the pathogen and create immunity against it. See what the main vaccines are and when they should be taken.
Passive immunization
Passive immunization happens when a person acquires antibodies produced by another person or animal. This type of immunization is normally obtained naturally through the passage of immunoglobulins, mainly of the IgG type (antibody), through the placenta, that is, through direct transfer from the mother to the baby.
Passive immunization can also be acquired artificially, by injecting antibodies from other people or animals, as in the case of snake bites, for example, in which the snake venom serum is extracted and then administered directly to the person. Learn about first aid for snakebite.
This type of immunization generates a faster immune response, but it is not lasting as is the case with active immunization.
How to strengthen the immune system
To improve the immune system it is important to adopt healthy lifestyle habits, such as regular exercise and a balanced diet, with foods rich in vitamin C, selenium and zinc. See what foods can strengthen the immune system.
Check out other tips to improve your immune system:
