Haptens

Definition

Haptens are small molecules that, when combined with larger carrier proteins, can elicit an immune response. Alone, they are not immunogenic and cannot trigger a specific adaptive immune response.

5 Must Know Facts For Your Next Test

1. Haptens require a carrier protein to become immunogenic.
2. They can bind to antibodies but do not activate T cells on their own.
3. Common examples include drugs like penicillin and small environmental chemicals.
4. The hapten-carrier complex is recognized by the immune system as foreign.
5. Hapten-induced allergic reactions are often delayed hypersensitivity reactions.

Review Questions

• Why can't haptens alone elicit an immune response?
• What is required for a hapten to become immunogenic?
• Give an example of a common hapten and explain its role in hypersensitivity reactions.

Related terms

Antigen: A substance that induces an immune response, typically by being recognized as foreign by the immune system.

Carrier Protein: A large molecule that binds to haptens and helps them become immunogenic.

Epitope: The specific region of an antigen that is recognized and bound by an antibody or T-cell receptor.