Antibodies are protein molecules that can identify and neutralise antigens. They are also known as immunoglobulins.
An antibody is made of four polypeptide chains with disulfide bridges in between. There is a constant region which allows it to bind to the phagocytic receptor. There is a variable region that is specific - it is complementary to the antigen it is binding with. This is dependant upon the primary structure of the polypeptide. There is also a hinge region which allows for a degree of flexibility when the antibody binds with more than one antigen.
How they work
A pathogen will probable have a use for its antigen. It could be used as a binding site to bind to the host cell. The antibody, by binding to the pathogen, will have blocked its binding site. This is known as neutralisation.
A large antibody has more than one specific variable region. This means that it can bind to more than one antigen and so many pathogens. The group of pathogens will be too large to enter the host cell. This is known as agglutination.
When the body is first infected, it takes a few days for the immune system to produce enough antibodies to combat the infection. This is known as the primary immune response. At the second infection, the immune response is much faster and antibodies are made at a rapid speed. Thisi s the secondary immune response.
Types of vaccination
Vaccination is a deliberate exposure to antigenic material, which activates the immune system to make an immune response and create immunity. The immune system manufactures antibodies and memory cells.
The antigenic material can be in different forms:
- Whole, live microorganisms with similar antigens but less harmful
- Harmless version of pathogen
- Dead pathogen
- Antigens from the pathogen
There are two ways to use vaccination. One is herd vaccination which provides immunity to all of the population at risk. Once enough people are immune, the disease can no longer spread. Another is ring vaccination. This is used when a new case of a disease is reported. All the people in the immediate vicinity are vaccinated.
Active immunity is immunity achieved by activation of the immune system. Lymphocytes manugacture antibodies and release them into the blood. This is long-term.
Passive immunity is provided by antibodies that may have been provided across the placenta or by intravenous injection. This is short-lived.
Natural immunity is gained in the normal course of living processes.
Artificial immunity is gained by deliberate exposure to antibodies or antigens.
Antibodies provided via breast milk makes the baby immune to diseases. This is natural, passive. Antibodies as a result of an infection are natural, active.
Antibodies provided by injection are artifical, passive. Antibodies made as a result of a vaccination are artificial, active.
Finding new drugs
New drugs are discovered by
- Accident e.g. penicillin
- Traditional medicine through plants
- Observation of wildlife e.g. animals self-medicating
- Modern research
There is a need to maintain biodiversity in order to find new potential uses in medicine.