Immunogenicity Health Dictionary

The characteristic of a substance that can provoke an immune response (see IMMUNITY). This includes how ‘foreign’ a substance entering or contacting the body is; route of entry; dose; number and period of exposure to antigen; and the genetic make-up of the host. The characteristics of molecules that determine immunogenicity are:

Foreignness: molecules recognised as ‘self’ are generally not immunogenic; the body tolerates these self-molecules. To be immunogenic, molecules must be recognised as non-self or foreign.

Molecular size: proteins with high molecular weights (over 100,000) are the most e?ective immunogens; those below 10,000 are weakly immunogenic; and small ones, for example, AMINO ACIDS, are non-immunogenic.

Chemical complexity: the greater the chemical complexity, the more immunogenic the substance.

Dosage, route and timing of antigen administration: all these are important factors.

n. the property that enables a substance to provoke an immune response, including foreignness (see antigen), size, route of entry into the body, dose, number and length of exposures to the antigen, and host genetic make-up.