Type II Hypersensitivity - Hunter Flashcards
What Ig causes type II?
IgG
What is the antigen type in type 2?
cell or matrix associated Ag
What is the effector mechanism of type 2?
FcR+ cells, aka phagocytes and NK cells
What is a good example of a type 2 reaction?
penicillin allergy
What are three types of hemolytic anemias caused by type 2?
transfusion reactions (ABO mismatch), drug induced, hemolytic disease of the newborn
Type 2 can present with autoantibodies to self proteins on cells or the (blank), or stimulate or block (blank)
on cell or INTRAcellular matrix; stim or block cell surface receptors
Explain frustrated phagocytosis?
Fc receptors on phagocytes bind to Abs on a self-cell, but can’t bind to the cell, so the granules get released into the tissue instead of the target cell and cause inflammation and injury
what are two examples of Ab-mediated cellular dysfunction?
Ab blocking of neurotransmitter uptake or Ab stimulating a receptor without a hormone present
Mismatched Transfusions Result in (blank)-Mediated RBC Destruction
Ab
What are the two paths that RBCs can be destroyed in ABO mismatch?
recipient Abs to wrong blood group bind to RBC which activates Fc receptor and is phagocytized OR Abs to ABO activate complement and cause HEMOLYSIS
How does penicillin cause hemolytic anemia?
Penicillin hapten binds to RBC; C3b binds; phagocytized; presented to CD4 T cell, TH2 activates B cells to produce anti-penicillin Abs
What class of Ig are anti-penicillin Abs?
IgG
The patient had an (blank) molecule capable of presenting drug-modified peptides
MHC
Is the first RH+ baby at risk for a Rh_ mom?
nope, second and on
what causes hemolysis of fetal RBCs in Rh problems?
maternal IgG anti-Rh Abs that cross the placenta
Severe anemia from Rh problems can cuase what in the fetus?
heart failure and massive edema (hydrops fetalis)
What are the effects of fetal hemolysis if it survives?
brain damage due to bilirubin buildup
Which coomb’s test measures the fetal blood?
direct
which coomb’s test measures the maternal blood?
indirect
describe the direct coomb’s test?
fetal blood (with maternal Ab bound) added to well, then add secondary Ab and measure agglutination
describe the indirect coomb’s test?
take maternal serum (containing anti-Rh + Abs), add fetal RBCs, then add secondary Ab and measure agglutination–SANDWICH ELISA
How do you treat hemolytic disease of the newborn?
intrauterine transfusion via umbilical vein in the placenta
If Rh ags are too sparse on the RBC surface to bind C1q and lyse via complement, how does the fetus have hemolysis?
by phagocytosis of the RBCs
Why is there less of risk of Rh alloimmunization when the baby is ABO INCOMPATIBLE with mom?
Mom will destroy the RBCs before she can become alloimmunized
Why are Rh- RBCs used for the intrauterine transfusion even though the baby is Rh+?
Mom’s Rh+ Abs won’t lyse the transfused RBCs
How long would it take a baby’s hematocrit to return to normal after birth if he suffered hemolysis in utero? Why?
6 weeks; NEED TO DEGRADE MOM’S IgG ABS!!
When do you give RhoGam?
28 weeks gestation and within 72 hours of delivery to Rh- women
How does RhoGam work?
Anti-Rh Abs oposonize Rh+ fetal RBCs for phagocytosis and prevent alloimmunization
Antibodies to Streptococcal M Antigens Cross-React with Antigens on (blank and blank) Tissue
heart and synovial
The strep cell (blank) stimulates the Ab response in rheumatic fever
cell wall
Some strep abs cross react with heart tissue causing (blank)
rheumatic fever
(blank) proteins share epitopes with proteins found in synovium, heart muscle, and heart valve
Group A Streptococcal M
(blank) contributes to the arthritis, carditis, and valvular damage
Molecular mimicry
What is the Tx for post-strep rheumatic fever?
NSAIDS, corticosteroids, and antibiotics
What determines the prognosis of post-strep rheumatic fever?
severity of the initial carditis
