What is an antibody?

Our body is programmed to react to protect itself against all kinds of organisms and chemicals that are foreign to it. Accordingly, the contact of our body’s immune system with a substance that is not familiar activates the mechanisms for removing this substance from the body and a conflict begins within the body. One of the important mechanisms among these mechanisms is antibody production.


What is an antibody?

Antibody (antibody) or immunoglobulin; They are complex molecules that can recognize and bind biological substances called antigens, which are found on substances found in nature or on cells belonging to living things and recognized by our body. Accordingly, each antibody has an antigen compatible with it and can only recognize it. In other words, individual antibodies are produced against each antigen. In this sense, our body has the capacity to produce antibodies against almost every biological substance found in nature.

Antibody production is a very complex process. It takes place under the control of a wide variety of donor cells and regulatory mechanisms. Accordingly, our immune system learns all the antigens in the body from infancy during the development process and does not develop an immune response against them. Apart from these, a foreign molecule entering the body immediately activates the cells called macrophages located in the front line of the immune system. Antigens are separated from these molecules that are processed by macrophages in a special way and presented to lymphocytes. Lymphocytes, on the other hand, initiate the production of an antibody compatible with the antigen and ensure that foreign molecules in the body are bound and excreted by antibodies.

There are 5 different types of antibodies detected in our body. These are called immunoglobulins (Ig) and differ in shape and function. It is named as IgG, IgA, IgM, IgD and IgE, respectively.

• IgG is the most abundant in blood and tissues; able to pass into breast milk and the unborn baby; It is a type of antibody that provides permanent immunity against diseases. The type of antibody that is expected to increase in the blood after vaccination is IgG. Likewise, it is an antibody given in serum therapy.
• IgA accumulates especially on the walls of the respiratory tract, mouth and digestive system; It prevents harmful factors from entering the body in these tissues that are in direct contact with the outside.
• IgM; It is an antibody that is produced rapidly in the first encounter with a harmful agent and provides an immune response.
• IgD; It is one of the main components of B lymphocytes responsible for antibody production.
• IgE; It is produced specifically for parasitic infections. In addition, the main antibody responsible for the allergy response is IgE.


What does an antibody do?

Our body consists of two different immune systems, natural and acquired. Natural immune elements; It creates a general response to factors that can harm the body and responds with the same response when faced with similar factors. However, elements of acquired immunity form an immune memory by performing detailed analysis against foreign factors. In this way, when similar factors enter the body again; Acquired immunity protects the body by giving a more effective and stronger response to the previously known factor. Here antibodies are one of the factors that make up acquired immunity.

Thanks to acquired immunity, people can catch some diseases only once or gain resistance in certain diseases for a temporary period. Similarly, thanks to this system, vaccines can be developed against various diseases. For; Thanks to antibody production, if harmful agents enter the body for the second time, the agents are destroyed by the antibodies. The ultimate aim of vaccine development studies is; It is to trigger the production of antibodies in the body without causing disease by the antigens of weakened microorganisms or factors.



The roles antibodies assume in the body can be summarized as follows:

• With the help of antibodies, immune cells in the body can easily bind to harmful substances and destroy or remove them.
• Antibodies surround the antigens all around and prevent harmful substances or microorganisms from acting.
• Extracellular elements of the immune system such as the complement system allow microorganisms to be killed by adhering to them by means of antibodies.
• Specific antibody derivatives such as IgA; By settling in tissues such as mouth, gastrointestinal walls and respiratory tract, it ensures that harmful factors are kept and disposed before they enter the body.
• Antibodies produced by the mother during pregnancy; passing through the placenta into the baby’s circulatory system; It protects the baby against diseases instead of the immune system that has not yet developed in the baby.
• Similar to pregnancy, postnatal breastfed babies; thanks to protective antibodies that pass into breast milk; It is protected against diseases during the breastfeeding period.



Diseases and Antibody Relationship

Antibodies are one of the important weapons of the immune system in fighting diseases. Especially in the fight against viral, bacterial and parasitic infections, the effective cleansing of the body from microorganisms depends on the correct and sufficient antibody response. In parallel with this, in various deficiencies and diseases of the immune system affecting antibody production; Since sufficient antibodies cannot be produced, susceptibility to diseases occurs. Likewise, antibody production is severely impaired in AIDS disease, which is considered the last stage of HIV infection, and this situation prepares the ground for the development of opportunistic infections.

In addition, antibody production itself can directly cause disease. Antibodies produced by the body against foreign substances under various conditions; It can bind to the body’s own antigens due to antigenic similarity, and this may cause disease. For example, since antibodies against the antigens of some bacteria that cause throat infection can bind to heart cells or kidney cells; Heart problems or kidney problems may occur in people for a few weeks after a throat infection.

Another problem is; during the healthy development of the body; The immune system, which is responsible for learning its own antigens, has a problem in performing this function. Accordingly, some cells may perceive the body’s own antigens as a threat and produce antibodies to the body itself. Also known as autoimmune disease, the body is at war with itself. Especially nowadays, health problems such as joint rheumatism, Type 1 diabetes, multiple sclerosis, inflammatory bowel diseases occur in this way.

Due to some diseases, the immune system is in the production of large amounts of antibodies randomly. As a result, an excessive antibody load is tried to be expelled by the kidney. Ultimately, kidney diseases can occur in the body as a result of obstruction and protein loss in the renal tracts.



Where are antibodies used?

In addition to the functions of antibodies in the body, they have various uses in medicine. These can be summarized as follows:

• Antibodies are used in blood tests of various diseases for diagnostic purposes. Antibodies are placed in test tubes to assist in the isolation and detection of special substances in the blood. Most of the blood tests are done in this way.
• Similarly, in various diseases, the types and amount of antibodies that rise in the body are measured by blood tests, and the diagnosis and follow-up of the disease is made. In this; diagnosis and follow-up of hepatitis; infections; autoimmune diseases such as celiac, arthritis, or lupus; Some cancers include typing and follow-up.
• According to the antibody response in the body, it can be determined whether the disease is still active, whether it has passed or whether the immune response is completed. It can also be understood by these serological tests that the agent was encountered before.
• Depending on the amount of antibody formed, information about the strength and effect of the immune response in the body can be obtained. Accordingly, when a high titer antibody response is received, it is understood that the body creates a strong immune response against the agent.
• Antibodies formed in the body can be isolated by special methods and used in serum treatment. Accordingly, especially in infectious diseases, antibodies produced by individuals are purified and the treatment of the disease is attempted by giving them to the blood of other patients through serum.
• Another treatment method used in recent years is monoclonal antibodies. These antibodies are bio-based drugs purified for a specific antigen and are used in the treatment of various allergic, rheumatological, autoimmune or specific diseases such as cancer.

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