Hypersensitivity Type II- Hunter Flashcards
How can you get immunohemolytic anemias?
transfusion reations (ABO mismatch)
drug-induced (e.g. penicillin)
hemolytic disease of the newborn
What are four types of type II hypersensitivity?
Immunohemolytic anemias
Microbal cross-reactions with host tissues (e.g. rheumatic fever)
Autontibodies to self-proteins on cells or intracellular matrix
Autoantibodies that block or stimulate cell surface receptors
What is this:
you get opsonization and phagocytosis of red blood cells resulting in hemolysis and anemia.
autoimmune hemolytic anemia
What is this:
you get opsonization and phagocytosis of platelets resulting in bleeding.
autoimmune thrombocytopenic purpura
What is this, epidermal cadherin is targeted resulting in antibody-mediated activation of proteases, and disruption of intercellular adhesions. Patients show up with skin vesicles (Bullae)
pemphigus vulgaris
What is this:
Neutrophil granules proteins are targeted and then neutrophils degranulate which reuslts in inflammation and vasculitis
vasculitits caused by ANCA
What is this:
noncollagenous proteins in basement membranes of kidney glomeruli and lung alveoli are attacked and results in complement and Fc receptor mediated inflammation. THe clinical manifestation is nephritis, ung hemorrhage.
goodpasture syndrome
What is this:
strep cell wall antigen cross reacts with myocardial antigen resulting in inflammation and macrophage activation in the heart and body. The clinical manifestation is myocarditis and arthritis
Acute rheumatic fever
What is this:
acetycholine receptor is attacked resulting in antibodies that inhibit acetylcholine binding which down-modulates receptors and results in muscle weakness and paralysis.
myasthenia gravis
What is this:
TSH receptors are targeted which results in antibody-mediated stimulation of TSH receptors that results in hyperthyroidism.
graves disease (hyperthyroidism)
What is this:
insulin receptors are targeted and you get antibody inhibition binding of insulin so people become hyperglycemic and ketoacidodic.
insulin-resistant diabetes
What is this;
intrinsic factor of gastric parietal cells are neutralized and you get decreased absorption of vit B12 thus you have abnormal erythropoiesis and anemia.
pernicious anemia
How can you get antibody mediated pathology?
antibody can bind to self and cause C3b to bind leading to opsonization and phagocytosis. f phagocyte cnnot phagocytize the tissue, it gets frustrated and releases its products onto the tissues causing inflammation and tissue damage.
Mismatched transfusions wil result in what?
antibody-mediated RBC destruction
What are the 2 mechanisms of anti-mediated RBC destruction?
1: anti-RBC antibodies engage Fc receptors on macrophages and promote phagocytosis and kiling
2: anti-RBC antibodies can activate complement and promote RBC hemolysis
Explain how you can get immunohemolytic anemia via drug induction…. use penicilin for your example.
RBC surface protein gets modified with a penicillin hapten-> this RBC/pencilin complex meets up with CD4 T cell-> this tell B cells to produce anti-penicillin antibodies-> antibodies bound to penicllin modifed RBC cause their destrution either by phagocytosis or my complement-mediated hemolysis
WHy is it scary to be a RH- mama with an RH+ fetus?
first pregnancy no big deal but the mom will see the positive RH+ and make antibodies to it. SOOO if she has another pregnancy with an RH+ baby the IgG antibodies will cross the placenta and cause hemolysis of fetal RBCs
What can severe anemia in a fetus cause?
heart failure and massive edema (hydrops fetalis)
If an anemic fetus survives, what are some complications that could develop?
brain damage due to heme metabolites (bilirubin)
What is the direct coombs test?
you take babies blood and moms antibodies and then take a fluorescent anti-antibody and see if it binds-> then you know if you will have an RH problem
What is the indirect coombs test?
take maternal serum, add Rh+ RBCs and wash out unbound antibody and then add anti-antibody and see if it binds
How do you give a baby a blood transfusion?
through the umbilical vein in the placenta
so how do you determine if Rh- mother has anti-Rh antibodies?
coombs test
How do you fix it if Rh- mother has anti-Rh antibodies?
give her Rhogamat 28 weeks of gestation and within 72 hours of delivery to Rh- women.
How does Rhogam work?
anti-Rh antibodies opsonize Rh+ fetal RBCs for phagocytosis and prevent alloimmunization
antibodies to streptococcal M can cross react with antigens on the heart and cause what?
rheumatic fever
How do you treat rheumatic fever?
NSAIDS, corticosteroids, antibiotics
