exam 4: tissue graft & transfusions Flashcards
what are the four different types of tissue grafts and their immune responses
- autograft - animals own tissue; no rejection
- syngenic graft - genetically identical animals; no rejection
- xenograft - grafts from different species; rejection
- allogenic graft - unrelated animals of same species; rejection
what is the difference between a graft disease and host disease
graft: immune response to alloantigens in the graft
host: donor T cells are activated by recipient APCs & attack recipient cells
how does the body tolerate fetal tissue?
- placental sequestration
- local factors
- systemic factors
what is placental sequestration?
fetal derived tissue that…
-does not express MHC II
-restricted MHC I expression,
- indolemaine 2,3-dioxygenase (IDO) production to dampen Th1 response
- regulatory cytokine production (Treg) to minimize fetus rejection
what are local factors to tolerate fetal tissue
uterine entrapment of APC
chemokine gene silencing by decidual stromal cells
what are systemic factors to tolerate fetal tissue
-expansion of maternal Treg cells with fetal specificity
-release of tolerogenic placental debris into maternal circulation
-immune modulation by progesterone and its downstream factors
what type of immunity predominates during pregnancy?
Th2
what is a type II hypersensitivity reaction due to blood transfusion
type II hypersensitivity reactions due to antibodies binding RBC proteins = complement activation, phagocytosis of RBC, and direct lysis
what is an alloimmune reaction due to blood transfusion
alloimmune: antibody from another member of the species binds antigen on affected patients RBC; could be due to mismatched blood transfusion or neonatal isoerythrolysis
what is a primary transfusion reaction
primary: patients antibody binds the patient’s self RBC antigen
what is a secondary transfusion reaction
secondary: patients antibody binds absorbed antigen on RBC
what are types of RBC antigens
glycoproteins, receptors, transport proteins, structural proteins, absorbed factors
in most species, does the primary or secondary immune response more likely to cause damage, why?
what species are the exception?
secondary immune response is more likely to cause damage because antibodies are formed after exposure to antigen
cats & humans are the exceptions because their antibodies are strong enough to cause damage the first time
what clinical signs may be observed during a transfusion reaction
pale mucous membranes
icterus
apnea
tachycardia
lethargy
what are the major blood groups in equine?
what antigens are of importance for isoerythrolysis?
what naturally occuring antibodies can horses have? is this rare?
7 blood groups = ACDKPQU
Aa & Qa are of importance for neonatal isoerythrolysis
anti-Aa & anti-Ca are rare, naturally occuring antibodies
describe neonatal isoerythrolysis in equine
-forms during blood exchange at birth
- negative Aa/Qa mares, positive Aa/Qa foals
-usually occurs with mares second foal, not the first
-colostrum with maternal antibodies will target paternal antigen present in foal causing hemolysis
what are naturally occurring antibodies in canines? what do they do?
DEA-3, DEA-5, DEA-7
these naturally occuring antibodies cause increased RBC removal during the first transfusion
what causes neonatal isoerythrolysis in canines? why is this important in 2nd transfusions?
DEA-1
will cause severe hemolysis in 2nd transfusions
which blood groups can cause severe hemolysis in 2nd transfusions in canines
DEA-1 & Dal
what blood group for canines is a good donor
DEA-4
what are feline blood groups? which ones are common or rare
type A (genetically A/A or A/B) common
type B (genetically B/B) rare
type AB (genetically A/A or A/B but have second gene that modifies some A into B so both are expressed on RBC) extremely rare
what antigen is unique to felines
the Mik antigen
what causes severe transfusion reactions in felines
A+ blood to B+ cats
mik+ blood to mik- cats
what are the naturally occuring antibodies in felines? what do each of them cause?
anti-A –> severe hemolysis
anti-B –> increased RBC removal during first transfusion of mismatched blood
anti-Mik –> hemolysis
what causes neonatal isoerythrolysis in felines? what can this cause
type B queens (they have anti-A Ab) mate with a type A tom and have type A/B or AB kittens
late term abortion
what test can be used to prevent transfusion reactions in dogs and cats
blood typing to screen for major antigens on RBC and avoid giving blood to different type:
dogs test for DEA-1
cats test of A,B or AB blood type
what is cross-matching?
determines if there are any antibody:antigen interactions
what is a major cross match?
1 drop donor RBC + 2 drops patient serum
patient Ab against donor RBC (problem)
what is a minor cross match?
1 drop patient RBC + 2 drops donor serum
donor Ab against patient RBC
what will mismatched blood samples result in?
agglutination or hemolyze
when should transfusions be performed?
only when necessary for patient survival…PCV < 10-15% or 50% acute decrease in PCV
