Theantigenis a molecule that is capable of binding to the product of immune response, such asantibodies.Immunogen是一种分子,能够绑定到公司吗mponents of an immune system and thereby triggering an immune response. Therefore, an immunogen is necessarily an antigen, but antigen may not necessarily be an immunogen.
Epitopespresent on the surface of the antigen allow for recognition by an antibody.
These are antigens that have entered the body externally e.g. through inhalation, ingestion, injection. Exogenous antigens will be taken up byantigen-presenting cells (APCs)and presented onto the cell surface viaMHC IImolecules. These will be recognized byCD4+ (T helper, Th) cells. The immune system will be activated to remove the invading pathogen expressing the foreign exogenous antigen from the body. This is the way researchers can generate specific antibodies in animals that bind to human proteins.
These antigens arise due to viral or intracellular bacterial infection. In this case,MHC Imolecules present these endogenous antigens toCD8+ (T cytotoxic, Tc) cells, which then secrete chemicals that cause the lysis of the infected cell.
An autoantigen is a protein, DNA or RNA that is recognized by the immune system to be foreign and hence becomes targeted for removal. This only occurs in patients suffering from autoimmune diseases such as Multiple Sclerosis and Systemic Lupus Erythematosus.
Viral antigens are those found on invading viruses.
Tumor antigens are produced by tumor cells and trigger an immune response in the host. These antigens can be presented by either MHC I or MHC II molecules on the surface of tumor cells. Tc cells that recognize these antigens may be able to destroy tumor cells. Tumor antigens are also useful as tumor markers in identifying tumor cells.
This is a class of antigens that cause non-specific activation of T cells which results in high numbers of polyclonal T cells and a cytokine cascade, leading to outbreaks of rashes and fever. Some examples of superantigens are bacterial enterotoxins and exotoxins.