Antigen is a immunogenic portion present on the foreign cell or substance. To combat that antigen or foreign cell, our body’s immune system produces antibodies.
Differences between antigen and antibody
| Sl.No | Properties | Antigen | Antibody |
|---|---|---|---|
| 1 | Name | Anti – Against Gen – Generate/ formation | Anti – Against Body-Against the body |
| 2 | Other names | Also called as Immunogens. | Also called immunoglobulins (Igs). |
| 3 | Symbols | The antigen can be represented by the “Ag” symbol. | The antibody can be represented by the “Ab” symbol. |
| 4 | Processing | The 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 | Composition | Antigens are mostly made of proteins but also contain carbohydrates, lipids, or nucleic acids. | Antibodies are made up of only proteins like glycoprotein, lipoprotein, etc. |
| 6 | Key part in structure | 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. |
| 7 | Role | The 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 |
| 8 | Size | The 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. |
| 9 | Structural difference | The structure of the antigen shows great complexity. | The structure of all classes of immunoglobulins is Y-shaped. |
| 10 | Specificity | The specificity of the antigen depends upon its epitope. | The specificity of the antibody depends on its paratope. |
| 11 | Foreignness | An 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. |
| 12 | Types | Antigens 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 disorders. | 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. |
| 13 | Prevalence | The 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 |
| 14 | Importance | The antigens help to determine the type of microbe or substance entered into the body. | The antibodies are more important to the person to prevent diseases and also kill pathogens and fight diseases. |
| 15 | Features | There are three specific features like being 1) Exogenous 2) Endogenous, and 3) Autoantigens. | 1) Specificity. 2) Diversity. 3) Immunological memory. 4) Immune tolerance. |
| 16 | Functions | The function of the antigens is to trigger the production of the antibodies. | 1) They activate the complement system is to destroy the pathogens. 2) Promotes the phagocytosis of foreign substances by neutrophils and macrophages |