Antigens are molecules found on the surface of cells that play an important role in the human body. They are integral in helping the immune system recognize foreign invaders and providing a defense against them. In this article, we will discuss the definition of antigens, the different types of antigens and their functions.
An antigen is a molecule that is recognized by the body’s immune system and triggers an immune response. Antigens can be found on the surfaces of bacteria, viruses, fungi, parasites, and other pathogens and can also be found on foreign substances such as pollens and foods. Antigens are often proteins but can also include carbohydrates and other molecules. In order for an antigen to produce an immune response, the body must recognize it as foreign and differentiate it from its own healthy cells. This recognition is accomplished by the body’s B-cells which are white blood cells responsible for monitoring and defending against intruders. B-cells contain receptors on their surface that bind to antigens and trigger the body’s protective response. The recognition of antigens is the basis for the development of vaccines as well as antibodies which are used to fight disease.
Antigens are molecules that are recognized and bound by antibodies, creating an antigen-antibody response. There are two main types of antigens: exogenous and endogenous. Exogenous antigens are foreign substances found in foods, bacteria, viruses, and toxins. Endogenous antigens are produced naturally within the body and include proteins, enzymes, and hormones.
Exogenous antigens are recognized by the immune system as foreign and stimulate the production of antibodies. Bacteria, fungi, viruses, and other parasites, as well as toxins, can all contain antigens. These antigens can be further divided into subgroups like lipopolysaccharides, which are a type of exogenous antigen, or enterotoxins, which are toxins released from certain bacteria.
Endogenous antigens are usually proteins and peptides that are derived from the breakdown of enzymes or hormones. These proteins and peptides can be self-antigens, meaning they are recognized by the body as part of itself, or they can be foreign antigens, meaning they are not recognized by the body as part of itself, but rather as foreign. Self-antigens lead to autoimmune diseases and can be caused by genetic mutations or alterations due to environmental factors.
Antigens serve several important functions in the human body. First, they are used by the immune system to identify and combat foreign pathogens, such as viruses and bacteria. The antigen binds to specialized receptors on the surfaces of white blood cells, which then activate a cascade of immune responses designed to eliminate the invader.
In addition to this primary function, antigens also play a role in the formation of memory cells during an immune response. Memory cells can quickly recognize and attack the same foreign pathogen if it enters the body again. Lastly, antigens help the body distinguish self from non-self. This is essential for preventing the body from attacking its own healthy cells.