Autoantigens are the self substances that elicit an immune response against the host’s cells or tissues.
- Usually, they become immunogenic after some structural modifications. For instance, one group of autoantigens comprises the structures isolated behind the blood-tissue barriers.
- These substances include the eye lens (behind the blood-ocular barrier), spermatozoids and seminal gland, thyroid gland, CNS cells, and some other structures.
- Under ordinary conditions, they do not come into contact with the host immune system.
- Therefore, antibodies don’t give rise against “hidden” cells, tissues and organs. However, if these structures are injured, the autoantigens become exposed to the immune cells.
- This enables the production of antibodies and autoreactive T cells that might be deleterious against the primary isolated tissues that become autoantigenic.
- Also, the origination of autoantigens is possible under the influence of various external factors – radiation, tissue crush, extreme cooling, drug treatment (e.g., nonsteroidal anti-inflammatory drugs, sulphonamides, colloidal gold products and others) as well as by impact from bacterial proteins and toxins or under the action of viruses (e.g, in case of infectious mononucleosis, viral hepatitis and many other viral infections).
Pathological autoantigens appear due mainly to the structural changes after the damage of macromolecules, cells and tissues (in burn disease, in cancer patients, after exposure to radiation, severe tissue crush and other similar cases).