Examples. For example, exogenous antigens are pathogens like bacteria, viruses, etc. or allergens like pollen and toxic food while endogenous antigens are the by-products of regular cell metabolism or molecular components of pathogens inside the infected cells.
Endogenous antigens are signals produced within your body's own cells (having been infected by a virus) that start an immune response. They alert cytotoxic T cells that a body cell is either infected with a virus, such as influenza, or has become cancerous.
Foreign antigens originate from outside the body. Examples include parts of or substances produced by viruses or microorganisms (such as bacteria and protozoa), as well as substances in snake venom, certain proteins in foods, and components of serum and red blood cells from other individuals.
Antigens generated endogenously within these cells are bound to MHC-I molecules and presented on the cell surface. This antigen presentation pathway enables the immune system to detect transformed or infected cells displaying peptides from modified-self (mutated) or foreign proteins.
The endogenous pathway is used to present cellular peptide fragments on the cell surface on MHC class I molecules. If a virus had infected the cell, viral peptides would also be presented, allowing the immune system to recognize and kill the infected cell.
Exogenous antigens are antigens that have entered the body from the outside, for example, by inhalation, ingestion or injection. The immune system's response to exogenous antigens is often subclinical.
There are three main types of antigen The three broad ways to define antigen include exogenous (foreign to the host immune system), endogenous (produced by intracellular bacteria and virus replicating inside a host cell), and autoantigens (produced by the host).
There are different types of antigens on the basis of origin:Exogenous Antigens. Exogenous antigens are the external antigens that enter the body from outside, e.g. inhalation, injection, etc. ... Endogenous Antigens. ... Autoantigens. ... Tumour Antigens. ... Native Antigens. ... Immunogen. ... Hapten.