Antibodies are the defense system of the human body, it is that army that detects elements that can be harmful to an individual and neutralizes them. Antibodies are called immunoglobulins that synthesize a type of leukocyte called B lymphocyte. A simple example that can help a little to understand such complicated terms is when a bacterium from outside the body enters it, the antibodies turn on their alarms and battle with the virus or bacteria to keep the person from getting sick.
Antibodies have a very similar structure, almost generic for all of them, they are formed by a protein that has a Y shape, what differentiates them is that at their ends a region of the protein is variable, allowing a great variety and the creation of millions of different antibodies, capable of fighting any type of disease that enters the body. This variable part of the protein is called a hypervariable.
The human body has the possibility of manufacturing millions of antibodies that in turn undergo mutations that generate greater diversity than what already exists in the body.
The B lymphocytes are classified into two types:
- Those that are responsible for the production of antibodies to fight infection.
- Those that remain in the body for years as part of the immune memory that each individual possesses. The latter makes it possible for the immune system to remember the presence of a harmful agent and proceed to neutralize it much faster.
The immunoglobulins are essentially proteins that function as antibodies. The terms antibody or immunoglobulin are basically the same. These are found in the blood, in various tissues and fluids. They are made by plasma cells that are derived from the B cells of the immune system, these in turn become plasma cells when activated by the binding of a specific antigen on their antibody surfaces.
Classically antigens are any foreign substance that elicits an immune response. They are also called immunogens. The specific region on an antigen that an antibody recognizes is called the epitope, or antigenic determinant.
An epitope is generally made up of a long chain of amino acid 5-8 on the surface of the protein. Amino acid chaining does not exist in a 2 dimensional structure if it does not appear as a 3 dimensional structure. An epitope can only be recognized in its form as it exists in solution, or its native 3D form. If the epitope exists on a single polypeptide chain, it is a continuous, or linear epitope. The antibody can only bind to denatured fragments or segments of a protein or to the original basic protein.
