Differences Between Antigens And Antibodies

The main difference between an antigen and an antibody is that an antigen is a foreign substance that enters the body, such as bacteria or viruses, while an antibody is a protein produced by the immune system to specifically target and fight against these antigens.

Antigens vs. Antibodies

Here are the main differences between antigens and antibodies:

Factors	Antigen	Antibody
Also called	Immunogens	Immunoglobulins
Molecular Type	Usually lipids, can also be proteins, carbohydrates, and nucleic acids	Proteins
Effect	Can cause allergic reactions or illnesses	Protects against the effects of the antigen, such as lysis or immobilization of the particle
Specific Binding Site	Epitopes – regions of the antigen where it interacts with antibodies	Paratopes – variable regions of the antibody that bind to epitopes
Origins	Origins outside the body	Always originate within the body
Size	Varies in size and complexity	Consists of two heavy chains and two light chains, forming a Y-shape structure
Production	Produced by the body in response to the presence of foreign substances	Produced by B cells in the immune system
Function	Recognizes and triggers an immune response against foreign substances	Binds to specific antigens, neutralizing or eliminating them
Diversity	Can have a wide range of structures and can be unique to each individual	Exhibits high diversity due to genetic recombination and mutation
Memory	Does not possess memory of past encounters	Can generate memory cells for rapid response upon subsequent exposure to the same antigen
Role in Immune Response	Serves as a target for antibodies and activates the immune system	Key component of the humoral immune response, providing targeted defense against specific antigens
Duration	Generally stable and long-lasting	Short-lived, but can be continuously produced upon re-exposure to the antigen
Diagnostic Use	Detection of specific antigens can indicate the presence of infections or diseases	Measurement of specific antibodies can indicate past exposure or immune response to certain pathogens