Antigens

Antigens are any substances that can trigger an immune response in the body. These foreign invaders can be proteins, polysaccharides, lipids, or nucleic acids, and they are typically found on the surface of pathogens like bacteria, viruses, fungi, and parasites. They can also be present on non-infectious substances, such as pollen, toxins, or even transplanted organs. When the immune system detects antigens, it initiates a cascade of events, including the production of antibodies and activation of immune cells to eliminate the threat and provide immunity against future encounters.

Antigens meaning with examples

• Exposure to the influenza virus introduces various antigens into the body, stimulating the immune system to produce antibodies specifically designed to combat these viral proteins. The generated immune response often results in the signs and symptoms of the flu. This specific recognition and targeting of the flu's antigens allows the body to recognize and combat the virus, hopefully, building up a form of immunity that might last through the flu season.
• Individuals with allergies react to environmental antigens such as pollen or dust mites, triggering an immune response that leads to symptoms like sneezing, itching, and inflammation. Their immune system mistakenly identifies these usually harmless substances as threats. This misdirected response indicates the presence of an allergen, which is a specific type of **antigen** triggering the immune system to go into overdrive.
• In blood transfusions, matching blood type antigens is critical to prevent a potentially life-threatening immune reaction. If incompatible blood types are mixed, the recipient's body will perceive the donor's blood cell antigens as foreign invaders, mounting a severe attack that can lead to hemolysis and organ failure, where their own immune system could kill the incoming blood.
• Vaccines work by introducing weakened or inactive antigens into the body, priming the immune system to recognize and respond to a real infection. This process allows the body to build immunological memory without causing illness. By being exposed to the attenuated virus's antigens, it allows the immune system to learn about this infection so that they can attack if there's a second infection.
• Autoimmune diseases arise when the immune system mistakenly attacks the body's own tissues because it identifies self-antigens as foreign. In conditions like rheumatoid arthritis, the immune system attacks the cells lining the joints as they don't recognize the antigens of your body as self. This misguided response triggers chronic inflammation and tissue damage.