What role does a carrier molecule play in immunity?

A carrier molecule plays a crucial role in enhancing the immunogenicity of haptens, which are small molecules that typically cannot elicit an immune response on their own due to their low molecular weight. When a hapten is chemically linked to a larger carrier protein, the combination creates a new entity that can be recognized by the immune system. This coupling transforms the hapten into a more complex structure that has the ability to stimulate a stronger immune response, including the production of specific antibodies.

While the other options mention potential roles related to the immune system, they do not directly address the specific mechanism by which carrier molecules function alongside haptens. The enhancement in immunogenicity is fundamental to vaccine design and the development of immunotherapeutics, wherein small antigens are made more visible and recognizable to immune cells through their association with carrier proteins.