15 Differences between antigen and antibody

An antigen is an agent present on foreign cell which is recognized by or immune system. It is an immunogenic portion present on the foreign cell or substance. These antigens are also present on cancer cells.

When the body recognizes them, it releases suitable antibodies that help to destroy those foreign or cancer cells.

To combat that antigen or foreign cell, our body’s immune system produces antibodies.

Differences between antigen and antibody
Antibody bound to an antigen

Differences between antigen and antibody

Sl.No Properties Antigen Antibody
1 NameAnti – Against
Gen – Generate/ formation
Anti – Against
Body-Against the body
2Other namesAlso called as Immunogens.Also called immunoglobulins (Igs).
3SymbolsThe antigen can be represented by the “Ag” symbol.The antibody can be represented by the “Ab” symbol.
4ProcessingThe antigen will be processed by the Macrophages, Dendritic cells, and B-cells are of
Antigen Processing cells (APC)
The Antibody will be processed by the Plasma and Memory B-cells.
5 CompositionAntigens are mostly made of proteins but also contain carbohydrates, lipids, or nucleic acids.Antibodies are made up of only proteins like glycoprotein, lipoprotein, etc.
6Key part in
An antigen contains the epitope region. It is the region that attaches to the antibodies.Antibody contains a paratope region. It is a variable region that
specifically binds to an epitope.
7RoleThe antigen plays a role in causing disease or evoking an allergic reaction.Antibody plays a role in the nullification of pathogens or harmful substances. They
precipitate the antigenic substance, lyse it or and lead to phagocytosis
8SizeThe antigen Size varies from one to another; the greater the size of the molecule, the higher
is its antigenicity.
The size of immunoglobulin is
variable according to the type of antibody.
The structure of the antigen shows great complexity.The structure of all classes of immunoglobulins is Y-shaped.
10SpecificityThe specificity of the antigen depends upon its epitope.The specificity of the antibody depends on its paratope.
11ForeignnessAn antigen from the outside environment is highly antigenic. So it is a foreign substance to the body.The antibody is produced by our
body’s immune system.
12TypesAntigens are grouped into two divisions
1) Foreign Antigens: It is also called Heteroantigens, these
antigens present in
bacteria, viruses, snake
venom, etc.
2) Self Antigens: It is also called Autoantigens; these antigens are present within the body and lead to autoimmune
Antibodies are divided into 5 different types

1) Immunoglobulin G: Most important of all the antibodies. It is present in the bloodstream and other body fluids. The important function is it can cross the placenta.

2) Immunoglobulin A: It plays an important role in
neutralizing the bacteria and virus. It is widely present in respiratory
secretions, saliva, tears, etc.

3) Immunoglobulin M: The function of the IgM is the same as IgG, but it cannot cross the placenta. It is the largest-sized antibody.

4) Immunoglobulin E: It is a secondary antibody. It helps to diagnose allergic-
reaction and diseases.

5) Immunoglobulin D: It is also a secondary antibody. They help in the activation of the B cell for the defense mechanism.
13PrevalenceThe antigens are found on bacteria, fungi, and viruses and also all different types of cells and biological substances.The antibodies are produced only by the lymphocytes
14ImportanceThe antigens help to determine the type of microbe or substance entered into the
The antibodies are more
important to the person to prevent diseases and also kill pathogens and fight diseases.
15FeaturesThere are three specific
features like being
1) Exogenous
2) Endogenous, and
3) Autoantigens.
1) Specificity.
2) Diversity.
3) Immunological memory.
4) Immune tolerance.
16FunctionsThe function of the antigens is to trigger the production of the
1) They activate the
complement system is to
destroy the pathogens.
2) Promotes the phagocytosis of foreign substances by neutrophils and macrophages

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