Avidity
The avidity (from Latin avidus, "greedy", also functional affinity ) of an antibody is the strength of a multivalent bond between antigen and antibody. This binding can be specific or multispecific. It is multispecific when an antibody reacts with different antigen determinants ( cross-reactivity ).
Monovalent interactions have a low avidity, bivalent interactions a high and polyvalent interactions a very high avidity.
A distinction must be made between the avidity and the affinity (also intrinsic affinity ) of an antibody: Affinity is the extent of a single antigen-antibody bond (expressed by the dissociation constant ). The avidity is the totality of these affinities . The avidity between a monovalent antigen and a bivalent antibody is therefore identical to the affinity.
In the course of an immune response , both the concentrations of ( polyclonal ) antibodies and the avidity against the antigen increase.
Web links
- Hans-Martin Jäck: Concepts of Immunology , pp. 10–11 ( PDF )
Individual evidence
- ↑ Axel M. Gressner, Torsten Arndt: Lexicon of Medical Laboratory Diagnostics . ISBN 978-3-540-23660-3 , p. 163.
- ↑ Wolfram Gerlich: Medical Virology. ISBN 978-3-131-53562-7 . P. 112.