Type II & III hypersensitivity Flashcards
Type II hypersensitivity is mediated by?
antibodies
Which antibodies mediated in Type II hypersensitivity? against what?
IgM and IgG against tissue Antigens(Ag)
Type III hypersensitivity is mediated by?
IgM and IgG immune complexes
what so bad about immune complexes?
deposition in glomeruli
C3b does what?
opsonisation
C5b and C5a do what?
C5a: enhance inflammation/phagocytes
C5b: MAC
2 main outcomes for Type II hypersensitivity?
- injury due to MAC
2. abnormal physiology (activation/inhibition)
2 example of abnormal physiology Type II hypersensitivity?
Graves Disease
Myasthenia Gravis
Classic Type II hypersensitivity injury?
transfusion reactions
tissue rejection
what are some transfusion reactions?
haemolysis, shock, nausea, vomiting, pain
why are erythrocytes targets for Type II hypersensitivity responses for drug allergies?
drugs like penicillin bound to RBCs/platelets, get targeted by immune system = splenic macrophages causing haemolytic anaemis or thrombocytopenia
what is haemolytic disease of newborn?
Mom is Rh -ve, baby is Rh +ve, mom makes antibodies against baby during birth. 2nd birth, mom’s antibodies attack fetus RBCs if they are Rh+ve
How to treat haemolytic disease of newborn?
Give mother anti-Rh antibodies within 24 hrs of delivery to remove fetal RBCs in circulation
What is Goodpasture syndrome?
antibodies made against type IV collagen: basement membrane > glomerular disease
What happens in Type II hypersensitivity for Graves disease?
TSH negative feedback loop is useless because antibodies are made that continuously activate the TSH receptor = hyperthyroidism (
What happens in Type II hypersensitivity for Myasthenia Gravis disease?
antibodies attack acetylcholine receptors in neuromuscular junction, internalized and degraded (inhibit function)
Type III hypersensitivity immune complexes occurs why? 2 reasons
complexes excessively produced
inefficiently cleared
How are immune complexes normally dealth with?
cleared by splenic macrophages
good efficient immune complexes are usually made up of what antibodies?
IgG with fixed complement
which are better? large or smaller immune complexes? why?
large complexes better because they activate complement better, removed from circulation efficiently by RBCs
3 reasons why immune complexes not cleared?
excess antigen
law affinity Ab
inefficient complement activation
How do immune complexes cause pathology?
deposition on vessel walls > inflammation >complement > activate mast, basophils, platelets
3 common outcomes of Type III hypersensitivity?
vasculitis
glomerulonephritis (BMs)
arthritis (joint synovium)
Farmer’s Lung is e.g. of what kind of hypersensitivity?
Type III hypersensitivity
