Haptens are small chemical groups that cannot stimulate antibody responses in their free soluble form, because they cannot cross-link B-cell receptors and do not recruit T-cell help.

Are haptens immunogenic?

Haptens are small compounds that penetrate skin and bind to epidermal proteins, generating “modified self” proteins as immunogenic antigens.

Why are haptens not Antigenic?

Haptens are incomplete antigens that do not cause an immune response upon binding because they cannot bind to MHC complexes. Haptens may bind with a carrier protein to form an adduct, which is also a complete antigen.