Antigen-antibody reaction

Antigen-Antibody Reaction

The antigen-antibody reaction is a specific chemical interaction between antigens produced by foreign substances and antibodies produced by the immune system. This reaction is fundamental to the body's immune response and plays a crucial role in the identification and elimination of pathogens.

Overview

An antigen is a substance that triggers the immune system to produce antibodies against it. Antigens can be bacteria, viruses, or other foreign substances in the body. An antibody, also known as an immunoglobulin, is a large Y-shaped protein produced by B-cells that is used by the immune system to identify and neutralize foreign objects such as bacteria and viruses.

Mechanism of Action

The antigen-antibody reaction involves the binding of an antibody to an antigen to form an antigen-antibody complex. This binding is highly specific, as the structure of the antibody is perfectly suited to match the structure of the antigen. This specificity is due to the unique structure of the antigen-binding site of the antibody, which is formed by the variable regions of the antibody's heavy and light chains.

The binding of the antibody to the antigen triggers a series of immune responses, including the activation of complement proteins, the phagocytosis of the antigen by macrophages and neutrophils, and the destruction of the antigen by natural killer cells.

Clinical Significance

The antigen-antibody reaction is the basis for many diagnostic tests in medicine, such as the ELISA test, the western blot test, and the immunofluorescence test. These tests use the specificity of the antigen-antibody reaction to detect the presence of specific antigens or antibodies in a patient's blood, which can indicate the presence of a specific disease or condition.

In addition, the antigen-antibody reaction is the basis for the development of vaccines. Vaccines work by introducing a harmless form of an antigen into the body, which triggers the immune system to produce antibodies against it. This prepares the immune system to quickly and effectively respond to future encounters with the actual pathogen.

See Also

• Immune system
• Immunology
• Vaccine
• Immunoglobulin