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| Home > Resource
> Antibody > Classification of antibodies |
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| Clonality |
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The antibody-binding site of an antigen is called an epitope.
Monoclonal antibodies are identical in binding to only one epitope, because
they were produced by clones of a single plasma cell. They were produced by
Kohler and Milstein for the first time in 1975. It is possible to produce
monoclonal antibodies from hybridoma cells, which is created by the fusion of
precursors of plasma cells with immortal cells in B cell lineage. Contrary to
monoclonal antibodies, antibodies recognizing antigens without distinguishing
epitopes are called polyclonal antibodies.
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Monoclonal |
Polyclonal |
| Source |
Hybridoma cell (spleen cell) |
Serum |
| Characteristics |
Homogeneous |
Heterogeneous |
Same immunoglobulin class and
subclass |
Diverse immunoglobulin classes |
| Recognize a single epitope |
Recognize diverse epitopes |
| No difference between batches |
Different with batches |
Produced from hybridoma cells
created by cell fusion |
Collected from serum of mammals
after immunization |
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| Isotypes |
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According to differences in their heavy chain constant
domains, antibodies are classified into five isotypes: immunoglobulin G (IgG),
immunoglobulin M (IgM), immunoglobulin A (IgA), immunoglobulin E (IgE),
immunoglobulin D (IgD). The five types of heavy chains are γ, μ, α, ε, δ.
There are subclasses in IgG, which are IgG1, 2. 3. 4 in humans.
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| Characteristics |
Ig G |
Ig M |
Ig A |
Ig E |
Ig D |
| Heavy chain |
γ |
μ
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α
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ε
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δ |
| Light chain |
λ or κ |
λ or κ |
λ or κ |
λ or κ |
λ or κ |
| Molecular weight |
150,000 |
900,000 |
160,000 for
monomer |
200,000 |
180,000 |
Additional protein
subunits |
-
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J |
J and s |
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| Structure |
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| Concentration in serum |
8-16 mg/ml |
0.5-2 mg/ml |
1-4 mg/ml |
10-400 ng/ml |
0-0.4 mg/ml |
| Percent of total Ig |
80 |
6 |
13 |
0.002 |
0.2 |
| Half-life |
23 days |
5 days |
5.5 days |
2. days |
2.8 days |
| Distribution |
Intravascular and extravascular |
Mostly intra-vascular |
Intravascular
and secretions |
On basophils and mast cells present
in saliva and nasal secretions |
Present on lymphocyte surface |
| Function |
Secondary response |
Primary
response |
Protects mucous membranes |
Protects against parasites(?) |
? |
Antiviral activity, antibacterial activity(gram
negative),
antitoxin activity |
Antiviral activity, antibacterial activity(gram
negative with lysozyme), |
Antiviral activity, antibacterial activity(gram
negative with complement), |
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Allergic activity |
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