Avidity

Avidity is the power by which a polyvalent antibody interacts with a polyvalent antigen. This is an empirical concept that is different from affinity.

Affinity expresses the strength of the interaction of one binding site with one antigen.

Avidity increases with the affinity of one binding site for one antigen and with the number of simultaneously acting binding sites.[1] Therefore, for example, pentamer IgM, antibodies with ten binding sites, can bind antigens with very high avidity, although the affinity of the individual binding sites tends to be lower.

Literature

 * HOŘEJŠÍ, Václav a Jiřina BARTŮŇKOVÁ. Základy imunologie. 3. vydání. Praha : Triton, 2005. 0 s. s. 65.  ISBN 80-7254-686-4.