Antigen-antibody interaction

Antigen-antibody interaction refers to the specific chemical interaction between antigens and antibodies. This interaction is fundamental to the body's immune response to foreign substances.

Overview

Antigens are substances (usually proteins) on the surface of cells, viruses, fungi, or bacteria. Nonliving substances such as toxins, chemicals, drugs, and foreign particles can also be antigens. The immune system recognizes and destroys, or tries to destroy, substances that contain antigens.

Antibodies, also known as immunoglobulins, are Y-shaped proteins produced by the immune system to help stop intruders from harming the body. When an antigen enters the body, the immune system produces antibodies that can attach to the antigen and make it easier for the immune cells to destroy the antigen.

Antigen-Antibody Binding

The binding of an antigen to an antibody is a key initial step in the immune response to eliminate the antigen. The strength of the binding between an antigen and an antibody is determined by the affinity of the antibody for the antigen. This affinity is created by the non-covalent interactions between the antigen and the antibody, including hydrogen bonding, electrostatic forces, and Van der Waals forces.

Types of Antigens

There are several types of antigens, including:

• Exogenous antigens: These are antigens that have entered the body from the outside, for example, by inhalation, ingestion, or injection.
• Endogenous antigens: These are antigens that have been generated within the body, usually as a result of cell death or the intracellular activities of bacteria or viruses.
• Autoantigens: These are the body's own proteins (or protein complexes) that can trigger an immune response.

Types of Antibodies

There are five different types of antibodies, including:

• IgG: This is the most common type of antibody. It's found in all body fluids and protects against bacterial and viral infections.
• IgM: This is the first antibody the body makes when it fights a new infection.
• IgA: This antibody is found in the linings of the respiratory tract and digestive system, as well as in saliva, tears, and breast milk.
• IgE: This antibody triggers allergic reactions.
• IgD: The function of this antibody is not entirely clear, but it appears to play a role in the immune response to certain foreign antigens.

See Also

• Immune system
• Immunology
• Antigen
• Antibody

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