Antigens are substances that trigger the production of antibodies as an immune system response. Antigens are made up of peptides, proteins, and polysaccharides, and choosing the correct antigen protein is a critical part of any custom antibody project. This article will outline the three key types of antigen protein and their main characteristics.
Exogenous Antigen Proteins
Exogenous antigen protein are those that enter the body from the outside, rather than being generated within. These antigen proteins generally enter the body through injection, inhalation, or ingestion.
Exogenous antigen proteins include bacteria and other pathogens that lead to infection and pollen or food particles that cause allergies. Exogenous antigen proteins are only present in the extracellular spaces, body fluids, and lymph nodes, not within the cell walls.
Endogenous Antigen Proteins
In contrast to exogenous, endogenous antigen proteins are produced inside the body as a result of cell metabolism. Endogenous antigen proteins can be either self or non-self antigens. MHC class I molecules and class II molecules located on the surface of APCs mediate all antigen presentation. However, endogenous antigens are also presented by MHC class II when degraded through autophagy.
Autoantigen Proteins
Autoantigens are complex or normal proteins that are known by the immune system of patients that are suffering from particular autoimmune diseases.
Examples of Antigens
Influenza Antigen Proteins
The influenza virus is extremely dangerous for public health, largely due to its high rate of mutation. On the surface of the influenza virus, there are antigen proteins called hemagglutinin and neuraminidase. These antigen proteins are capable of changing rapidly, escaping detection by antibodies.
Blood Group Antigen Proteins
Red blood cell antigen proteins and sugars coat red blood cell surfaces. A, B, and O antigens are sugars and the Rh antigen is a protein that can be present or absent. These antigens are combined to create blood types such as O+, B-, etc. Prior to the study of antigen proteins, many blood transfusions were mismatched and many people died as a result.
Antigen Proteins for Custom Antibody Development
Singular antigen proteins are available to purchase from Fortis Life Sciences to help research and create custom antibody production. Fortis Life Sciences has a range of antigen proteins for use as a positive control in immunoassays, helping with the research and development of a range of antibodies, vaccines, and more.
