Antigens

Antigens are substances that are recognized by the immune system as foreign and potentially harmful. They can be proteins, carbohydrates, lipids, or nucleic acids.

Exogenous antigens are those that enter the body from the outside environment, such as bacteria, viruses, and toxins. Endogenous antigens are those that are produced inside the body, such as cancer cells and proteins that are released from damaged cells.

Antigens trigger the production of antibodies by B cells, activate T cells, and cause inflammation. These responses are all part of the immune system's attempt to eliminate the antigen and protect the body from infection or disease.

Epitopes are the parts of an antigen that are recognized by antibodies. They are usually small, linear sequences of amino acids or sugars.

Haptens are small molecules that are not recognized by the immune system on their own. However, they can trigger an immune response when they are attached to a carrier protein. This is because the carrier protein makes the hapten appear larger and more foreign to the immune system.

There are a number of ways to protect ourselves from antigens, including vaccination, handwashing, using condoms, and avoiding contact with sick people.