Our adaptive immune system is critically dependent on how well the antigen receptors on our lymphocytes can distinguish invading antigens in our body. With the bonding of an antigen to the antigen receptor the proper response can be triggered. Antigen receptors that are found on a specific cell are identical but receptors on other cells differ. Due to this structural variation area that interacts with antigens, cells can distinguish many antigens. The variations of antigens are vast therefore the antigen receptor only binds to a small portion of the antigen that are structurally complementary. The topic of antigen receptors is crucial to our various responses of foreign materials and how we are able to fight off new viruses continuously.
The role of antigen receptors:
Antigen receptors differ on B lymphocytes and T lymphocytes. On B cells there are membrane-bound antibodies and on T cells there are T cell receptors (TCR’s). Membrane bound antibodies can recognize many types of chemical structures. B cell receptors and secreted antibodies can recognize shape conformation of macromolecules; proteins, lipids, carbohydrates, nucleic acids and chemical moieties. T cell antigen receptors only recognize peptide bounded to (MHC) molecules. This means T cells can only recognize cell associated microbes. Antigen receptor chains are associated with membrane proteins that function to deliver intracellular signals. With antigen recognition the signals are transmitted to the cytosol and the nucleus can cause the lymphocyte to divide into an identical clone. The B cells can also release antibodies which are also called immunoglobulins to fight of alien substance. These antibodies are the effector molecules of humoral immunity. They are responsible for attacking antigens that triggered the response. Antibodies can remain in the body for months providing immunity without the presence of the antigen.
Information about antibodies:
The antibody is almost identical to the antigen receptor of the cell that produced it. The basic structure of an antibody is a y shape. The structure of the antibodies has two polypeptide chains that are linked by peptide bonds. There are heavy chains in the structure and light chains. The light chains are made up of a V (variable) domain and one C (constant) domain, while the heavy chains can have up to four c domains. According to the C domains the antibodies can be grouped into several groups and based on their group they can also do different activities. Some example of the immunoglobulin groups is IgG, IgM, IgA, IgD, and IgE. During maturation of the lymphocytes genes that encode antigen receptors are brought together. For example, in B cells the Ig gene undergoes recombination in the bone marrow, and the TCR gene in T cells undergo recombination in the thymus.
As a precaution during their maturation lymphocytes have to go through several checkpoints. Lymphocytes with functional antigen receptors can be expanded. Other lymphocytes that recognize their self- antigens are negatively selected and don’t pass the checkpoints. These checkpoints are there to ensure that cells won’t harm themselves.
Therefore, through these points given it is evident that antigen receptors play key roles. With antigen receptors we are able to provide proper responses to foreign invaders aiding are adaptive immune system. Antigen receptors come in various forms leading to a more complex defend system. On top of that our system double checks itself to make sure that before maturation lymphocytes meet all their useful requirements. Antigen receptors play such an important role in our immune system studying in detail replication and recombination may help us develop counter measures to new viruses.