It's a common misconception that antibodies are proteins that bind to antigens simply because they're both proteins. In reality, antibodies are much more complex than that and have more than just one job in the immune system. Antibodies are produced by B cells, which are immune cells in the blood that protect against pathogens and infected cells. Each B cell produces antibodies with a unique idiotype—a chain of amino acids—that determines its shape and ability to bind with an antigen. At birth, an infant has about 1 million different B cell lines producing these types of antibodies; this diversity helps ensure that our bodies can fight off any pathogen we encounter throughout our lifetimes.
You probably know that antibodies are proteins that recognize and bind to antigens. But did you know that each antibody has two different sites for binding? The first site, called the paratope, binds to a specific part of the antigen called the epitope. The second site is known as the idiotype. Each antibody can recognize only one particular antidotal epitope sequence, which means that there are millions of different possible combinations of antibodies with their own unique idiotypes!
The paratope is the part of an antibody that binds to a specific part of an antigen called an epitope. It consists of 2 domains, each of which has a different shape because it binds to a different part of the antigen.
You may be wondering how antibodies can recognize a specific antigen, such as tuberculosis or influenza, if they're produced by B cells and each B cell produces antibodies with a unique idiotype. The answer is: idiotype diversity. Each antibody can only recognize one particular epitope sequence, called the idiotype. This means that there are thousands of different immune responses possible by combining different combinations of idiotypes in each B cell population.
The chain of amino acids in this region determines the idiotype, which is unique to each antibody. The two chains are called the heavy and light chains.
The DNA molecule carries all of the information required by a cell to make proteins and perform other tasks necessary for life. The letters A, T, G and C (adenine, thymine, guanine and cytosine) form a sequence of nucleotides that encodes all of our genetic information. In humans there are approximately 20,000 genes encoded on 23 pairs of chromosomes in each cell nucleus. Each gene has an associated stretch of DNA called an exon that can be translated into protein during translation or transcription (processes where genetic information is read out). The noncoding regions between exons are called introns. Introns contain no useful information but are not removed from RNA transcripts during splicing because they code for signals telling ribosomes where to add amino acids during translation into proteins
B cells, or B lymphocytes, are a type of white blood cell. They're produced in the bone marrow and travel to the lymph nodes where they protect against pathogens and infected cells.
The body's immune system has the ability to produce millions of different antibodies. This diversity is achieved by a process called somatic hypermutation, which occurs when B cells multiply in response to an infection. During this process, the cell's DNA encodes the amino acid sequence of its antibodies and produces a new antibody with a unique idiotype (a part of an antibody that binds to an antigen). The newly encoded antibody is then secreted into the bloodstream or lymphatic fluid where it can fight against any foreign antigens that enter its path.
As you know, antibodies are proteins produced by B cells. These immune cells protect the body from foreign invaders and infected cells by recognizing antigens that are not native to our bodies. Each B cell produces a unique antibody with a different idiotype (a specific combination of CDRs), which is encoded in each cell's DNA.
This process begins at birth: at this time there are about 1 million different B cell lines producing antibodies with different idiotypes in an infant's blood—these antibodies were inherited through the mother's genes or were generated after exposure to pathogens during pregnancy.*
To understand why antibodies are so specific and target only certain antigens, you have to first understand how they work. Antibodies are proteins that are made by B cells, a type of white blood cell. They have two sites on them: the antigen binding site (Fab region) and the constant region. The antigen binding site (also called the paratope) binds to a specific part of the antigen called an epitope. The constant region helps determine when and where an antibody will bind with its epitope, or what kind of molecule it can bind with.
The paratopes for all antibodies share a common structure: two arms connected by loops to form a Y-shape
I hope that you now understand the role of antibodies and how they work. So next time you get a cold, don't worry! It's just your body's way of helping you fight off infection by making more antibodies