Type II HSRs Flashcards
What are type II HSRs?
IgM/IgG recognizes an innocuous cell surface molecule as foreign leading to Ab-mediated cell death
What are the 3 Ab-mediated cell deaths?
- complement activation = MAC
- ADCC (NK Cells)
- opsonization = phagocytosis (IgG!!)
Ig___ mainly activates complement
IgM
Ig___ mainly activates ADCC
IgG1
What receptor do NK cells express that IgG binds to induce cell lysis?
FCGRIII
What are 3 examples of type II HSRs?
- mismatched blood transfusions
- hemolytic disease in new borns
- drug induced anemia
What is mismatched blood transfusions?
IgM binds to blood antigens due to the wrong blood type being presented
What is hemolytic disease in new borns?
Rh+ fetus and Rh- mother.
Anti-D IgG made in second pregnancy resulting in fetal RBC lysis
What is drug induced anemia?
antibodies formed against mediation that binds to RBC surface resulting in lysis
Why do most people possess IgM against blood antigens they don’t express?
common microbes express similar antigens resulting in Ab against any non-self blood antigen
What is dangerous about RBC lysis?
high levels of hemoglobin that breaks down into porphyrin which metabolizes to toxic billirubin
How does the mother’s immune system create protection for re-exposure of Rh+?
the mother will generate anti-D memory B cells which generate IgG for next exposure
Why is a mother’s secondary exposure of D+ easier to achieve with fewer D+ RBC than the first exposure?
she has memory B cells which have a lower threshold for activation
Ig___ can pass the placental barrier
IgG
What does it mean the fetal RBC are attacked?
mothers anti-D antibodies bind to fetal Rh+ RBC and fetus own NK cells lyse fetal RBC
