Antigen-antibody interaction

In the blood, the antigens are specifically and with high affinity bound by antibodies to form an antigen-antibody complex.

The first correct description of the antigen-antibody reaction was given by Richard J. Goldberg at the University of Wisconsin in 1952.

The antigenic determinant or epitope is recognized by the paratope of the antibody, situated at the variable region of the polypeptide chain.

[4] The principles of specificity and cross-reactivity of the antigen-antibody interaction are useful in clinical laboratory for diagnostic purposes.

Acquired immunity depends upon the interaction between antigens and a group of proteins called antibodies produced by B cells of the blood.

[5] In an antibody, the Fab (fragment, antigen-binding) region is formed from the amino-terminal end of both the light and heavy chains of the immunoglobulin polypeptide.

This region, called the variable (V) domain, is composed of amino acid sequences that define each type of antibody and their binding affinity to an antigen.

Such indirect bonds can contribute to the phenomenon of cross-reactivity, i.e. the recognition of different but related antigens by a single antibody.

Reciprocally, the equilibibrium dissociation constant Kd will be: The antibody-antigen binding kinetic can be described by the rate equation of a second-order reversible reaction.

[17][18] Antigen-antibody interaction is used in laboratory techniques for serological test of blood compatibility and various pathogenic infections.

[19] Sophisticated applications include ELISA,[20] enzyme-linked immunospot (Elispot), immunofluorescence, and immunoelectrophoresis.

[27][28] It acts on antigen-antibody reaction in which the antibodies cross-link particulate antigens resulting in the visible clumping of the particle.