What is the Difference Between Epitope and Hapten?

The main difference between an epitope and a hapten lies in their structure and immunogenicity. Here are the key differences:

• Epitope: An epitope, also known as an antigenic determinant, is the part of an antigen that is recognized by an antibody, B-cell receptor, or T-cell receptor. Epitopes are generally thought to be equivalent to 5-15 amino acids or 3-4 sugar molecules. They are portions of foreign proteins or self-proteins that are recognized by the immune system.
• Hapten: A hapten is a small molecule that by itself is not immunogenic but can act as an antigen when it binds to a larger protein molecule. Haptens are essentially incomplete antigens that can elicit an immune response only when attached to a large carrier, such as a protein. When they bind to a carrier protein, they act as epitopes.

In summary, an epitope is a portion of an antigen that interacts with the immune system, while a hapten is a small molecule that cannot elicit an immune response by itself but can act as an epitope when bound to a larger carrier protein.

Comparative Table: Epitope vs Hapten

Here is a table highlighting the differences between an epitope and a hapten:

Both epitopes and haptens are important structures involved in the immune response process, and they can bind to antibodies. However, epitopes are part of an antigen that serves as an antigenic determinant and can elicit an immune response on their own, while haptens require a larger carrier to trigger an immune response.