What is Antigen? Definition, Meaning & Example
An antigen is a foreign substance that the immune system recognizes and attacks, stimulating an immune response.
TL;DR: An antigen is a foreign substance that the immune system recognizes and attacks, stimulating an immune response.
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Antigen: An antigen is a foreign substance that the immune system recognizes and attacks, stimulating an immune response.
Explanation
Antigens can be proteins, carbohydrates, or other molecules on the surface of pathogens or cells. When the immune system detects antigens, it produces antibodies that bind to and neutralize the antigen. The immune system remembers antigens it has encountered before, providing immunity to future infections. Vaccines work by introducing antigens that stimulate immune response without causing disease. The human immune system distinguishes self from non-self by recognizing antigens. Transplant rejection occurs when the immune system recognizes foreign antigens on donor tissue. Understanding antigens is essential for immunology, vaccination, and treating autoimmune diseases.
Example
When you get a vaccine, you receive antigens that stimulate your immune system to produce antibodies against a disease without getting sick.
Frequently Asked Questions
How does the immune system recognize antigens?
The immune system produces antibodies that have specific shapes complementary to antigens. When an antibody binds to an antigen, the immune system recognizes the pathogen as foreign. Memory cells remember antigens from past infections.
Why do some infections cause immunity while others do not?
Pathogens that produce strong antigenic responses trigger good immune memory. Pathogens that hide antigens or mutate quickly evade immunity. The variability in antigenic strength determines immune durability.
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