Flashcards in Immunohematology ABO/Rh (complete) Deck (33):
How common are the blood types?
In US white pop'n:
In US black pop'n:
same but more B and less A
Very different throughout the world
O common for South Am, rare in China
B common in Vietnam
OVERALL: AB is the RAREST blood type
What are the red cell Ags in the blood types?
O => H Ag
A => A Ag
B => B Ag
AB => split 50/50 A&B
Bombay => h Ag
Which ABO antibodies are in the plasma of each blood type?
O => anti-A & anti-B
A => anti-B
B => anti-A
AB => none
Bombay => anti-A, anti-B, & anti-O
Persons w/ O blood can receive which type of blood?
Persons w/ A blood can receive which type of blood?
A & O
Persons w/ B blood can receive which type of blood?
B & O
Persons w/ AB blood can receive which type of blood?
Persons w/ O blood can donate which type of blood?
Persons w/ A blood can donate which type of blood?
A & AB
Persons w/ B blood can donate which type of blood?
B & AB
Persons w/ AB blood can donate which type of blood?
What are the possible genotypes of O blood?
What are the possible genotypes of A blood?
AA or AO
What are the possible genotypes of B blood?
BB or BO
What are the possible genotypes of AB blood?
What is the antibody class of most ABO isohemagglutinins?
This is especially important when you think about pregnancy!
Mom doesn't launch immune response to fetus b/c IgM can't cross the placenta
Explain the ABO Ag situation in a person with Bombay blood type
- Final sugar not placed in "core" Ag b/c they lack the transferase gene that does this
- Therefore no additional sugars (e.g. A or B) can be put on penultimate sugar
Those w/ Bombay blood can still have functioning glycosyltransferases that put A or B on penulti sugar, but they can't do so w/o final sugar on the end of "core" Ag
What are the consequences of a transfusion of non-Bombay blood into a patient with Bombay blood?
Bombay blood has anti-O, anti-A, and anti-B
A non-Bombay transfusion would launch an immuno response on the pt's own blood
Define the crossmatch
A lab test! Done after matching ABO and Rh
- Prospective recipient's plasma is mixed w/ prospective donor's RBCs
- If red this indicates hemolysis
NOT compatible if it turns red or there is clumping
Explain why the crossmatch is important
- Otherwise complement-mediated hemolysis would occur
- This can lead to acute renal failure
Explain how red cells are destroyed following a mismatched transfusion and why this may be devastating to the pt
- Via complement-mediated hemolysis
- Free Hb is then deposited in the kidneys => acute renal failure
What are the techniques of a direct antiglobulin test?
- Take recipient RBCs
- Wash them
- Add anti-IgG Ab
- If agglutination, *positive* test
What are the techniques of a indirect antiglobulin test?
- Take donor RBCs
- Add recipient plasma
- Wash unbound proteins
- Add anti-IgG Ab
- Agglutinates if positive
Antiglobulin crosslinks the bound Abs
The direct antiglobulin test is designed to answer which questions?
Is there Ab *already* on these cells?
The indirect antiglobulin test is designed to answer which questions?
Is there unexpected Ab to red cell Ags in the plasma of this potential recipient?
What is a heterophile Ab?
- Cross-reactive Abs
What is a common disease in which one type of heterophile Ab is increased enough to be useful diagnostically?
- Abs produced in mono also cross-react w/ horse RBCs
- A quick and cheap test!
In the Hemolytic Disease of the Newborn explain the consequences of severe hemolysis in the newborn
- Causes high levels of bilirubin (presents as jaundice)
- Bili can cross the BBB and damage the basal ganglia => cerebral palsy or fetal death
In the Hemolytic Disease of the Newborn explain the way in which the mother becomes sensitized
- Happens in last trimester, especially at time of delivery
- Rh(D)- mom is exposed to Rh(D)+ baby's blood
- Mom produces IgM to Rh(D) => becomes IgG and produces memory T cells to Rh(D)+
- Those Abs cannot be used b/c there's no more baby
In the Hemolytic Disease of the Newborn explain the class of antibody to Rh(D) the mother makes
CAN cross the placenta in future pregnancies
In the Hemolytic Disease of the Newborn explain the consequences of sensitization to subsequent fetuses
- Mom's IgG from previous exposure can now cross the placenta and can attack fetus's RBCs
- leads to jaundice and potentially other problems
In the Hemolytic Disease of the Newborn explain the role of Rh-immune globulin (RhoGAM)
- Mom receives IgG Ab to Rh(D)+ at the time of delivery
- These Abs combine w/fetal RBCs, opsonize them and are destroyed before they immunize her
- Whole point is to prevent sensitization (immunization) of mom to Rh(D)+
- Mom must do this at each pregnancy
Prevent hemolytic disease of the newborn