Hypersensitivities II Flashcards
What is type II hypersensitivity?
Antibody-mediated hypersensitivity
based off the bodys immune system attacking its own cells
What antibodies does Type II involve?
IgM or IgG
* Directed against cell or tissue surface antigen
How does the phagocytosis occur?
igM or igG binds to the cell surface antigen
C3b is deposited on the cell surface
C3b receptor on phagocyte causes phagocytosis to occur
What happens if the antibodies bind to receptors?
dysfunction
When is Fc mediated inflammation most common?
Most common when antibodies are deposited in fixed structures, e.g basement membranes, extracellular matrix
What by-products of complement activation recruit immune cells?
C5a, C3a
What is the function of the recruited immune cells?
They release enzymes and mediate tissue damage
What is myasthenia gravis?
antibodies directed against Ach receptors
What is Antibody-Mediated Cell dysfunction?
Occurs when the antibody response is directed at a cell receptor, it can either inhibit or enhance receptor function
The cells are not directly injured
When does a type II hypersensitivity reaction occur?
within hours of exposure to a sensitised host
What is type II hypersensitivity commonly involved in?
Immune-mediated and autoimmune diseases
* Autoimmune haemolytic anemia (AIHA, IMHA)
* Neonatal isoerythrolysis
* Pemphigus diseases
* Myasthenia gravis
Explain neonatal isoerythrolysis
- The mare and the foal have two different blood types
- During pregnancy the mare can become exposed to the foals blood
- The mare can then start to produce antibodies against the foals blood type
- These antibodies can cross the placenta in the last trimester of pregnancy
- Haemolysis of the foals blood cells when born
What is Antiserum specifically directed against?
the Fc portions of immunoglobulins
