Characteristics
|
Antigen
|
Antibody
|
| Molecule Type |
Usually, proteins may also be polysaccharides, lipids or nucleic acids. |
Proteins |
| Definition |
These are substances that provoke an immune response. |
These are Glycoproteins that are secreted by immune cells (plasma cells) in response to a foreign substance (antigen). |
| Effect |
Cause disease or allergic reactions. |
Protect the system by lysis of antigenic material. |
| Origin |
Within the body or externally. |
Within the body. |
| Parts |
Highly variable with different structural conformations and is usually composed of different epitopes. |
Composed of three main parts:
-Two light chains
-Two heavy chains
-Four polypeptides |
| Prevalence |
Exists in all types of cells; mostly found in viruses, bacteria, and fungi. |
Only present in some types of cells. |
| Synonyms |
Immunogens |
Immunoglobulins |
| Specific binding site |
Epitope |
Paratope |
| Complexity |
Medium; exists due to random mutations in the cell’s gene. |
Very High; Complex chemical that bonds to a very specific Antigen. |
| Source |
Usually from a foreign substance (viruses, and bacterial and fungal toxins). |
Naturally produced by the body (B lymphocytes or B cells). |
| Kinds |
There are three basic kinds of antigens (Exogenous, Endogenous, and Autoantigens) |
There are five basic kinds of antibodies (IgG, IgM, IgA, IgE, and IgD). |
| Examples |
Exogenous antigens: bacteria, viruses, fungi, etc.
Endogenous antigens: Blood group antigens, HLA (Histocompatibility Leukocyte antigens), etc.
Autoantigens:Nucleoproteins, Nucleic acids, etc. |
Breast milk, tears, saliva, sweat, and mucus. |