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Antibody specificity
1. Bind to a very specific molecule
2. The molecule they bind to is an antigen
3. Antibodies will be made against virtually any
molecule, even molecules that have never
existed
Antibody generation
1. At birth, you have genes coding for thousands
of antibodies.
2. These will bind weakly to most antigens.
3. Following weak binding, antibodies are
modified randomly, until more strongly binding
antibodies are produced. This process is call
affinity maturation
Antibody structure
1. Y- shaped, with 2 binding sites
2. Therefore can aggregate cells, viruses, or
other structures with more than one copy of
an antigen
3. Antibodies have a variable region and a
constant region. The binding sites are in the
variable region.
A bacteria has multiple antigens
Antibody A
Antigens
Components
of cell wall
Binding sites
Bacterial cell
Antibody B
Antibody subclasses
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IgG – most abundant
IgM – “immature” Ab, lower affinity
IgA – in secretions
IgE – responsible for allergies
IgD
Lymphocytes
1. There are 2 major types of lyphocytes: B
lymphocytes and T lymphocytes
2. B lymphocytes make antibodies
3. T lymphocytes have Ab-like molecules on
their cell membrane, which are the T-cell
receptors