Hypersensitivity is an immune response that damages the body's own tissues. There are four or five types of hypersensitivity that often described, each is a different way the immune system can damage the host.
This is mediated by IgE.
This is when a problem is caused by the presence of antibody-antigen complexes being deposited in the tissues. It is the problem in rheumatoid arthritis and serum sickness. Normally the complexes are cleared by the body, but it is not known why this doesn't happen in Type III hypersensitivity.
This is delayed type hypersensitivity, a form of hypersensitivity where antibodies are not involved. It is mediated by T-helper cells, and is a form of cell mediated immunity.
It is seen in tuberculosis.
Even though it can protect the body, it does so by damaging the host, and is thus characterised as hypersensitivity.
This is an additional type that is sometimes (often in Britain) used as a distinction to Type II. It includes diseases like Grave's disease where an antibody interacts with a cell receptor, triggering a response.Type I - anaphylactic hypersensitivity
Type II - antibody attaching to cells
Type III - immune complex hypersensitivity
Type IV - delayed type hypersensitivity
Type V - stimulatory hypersensitivity
