Type 2 Hypersensitivity Flashcards
What is type 2 hypersensitivity?
Antibody mediated
Which antibodies are involved?
IgG
IgM
What cells are targeted?
Cell bound antigens
- exogenous = blood group antigens, rhesus D antigen
- endogenous = self antigens
What are the mechanisms?
Tissue/cell damage
Physiological change
How can it cause tissue/cell damage?
Complement activation
- cell lysis
- neutrophil recruitment (C3a/5a)
- opsonisation (C3b)
Antibody-dependent cell cytotoxicity
- NK cells
What diseases are due to complement activation?
Haemolytic disease of the new-born
Transfusion reactions
What is the antigen for haemolytic disease of the new-born?
Rhesus D
What is the antigen for transfusion reactions?
ABO system
What disease are due to anti-body dependent cell cytotoxicity?
Autoimmune haemolytic anaemia
Goodpasture’s syndrome
What is the mechanism of transfusion reactions?
Incompatibility in ABO or rhesus D antigens
RBC lysis induced by type 2 hypersensitivity - IgM
What is the mechanism of haemolytic disease of the newborn?
Rh+ father + Rh- mother
Rh+ antigens get into mothers blood during delivery
Next child - mother has IgG against Rh+
How is haemolytic disease of the new-born investigated?
Coombs test
What is a direct coombs test?
Direct antiglobulin test - tests in vitro
What is an indirect coombs test?
Indirect antiglobulin test - tests in vivo
How is haemolytic disease of the newborn managed?
RhoGAM given to mother after birth of Rh+ child
How can it cause physiological change?
Receptor stimulation
Receptor blockade
What disease is due to receptor stimulation?
Graves’ disease
What is the antigen for Graves’ disease?
TSH receptor
What disease is due to receptor blockade?
Myasthenia Gravis
What is the antigen for myasthenia gravis?
Acetylcholine receptor
How can type 2 hypersensitivity be managed?
Anti-inflammatory drugs
Plasmapheresis
