Immunohemotology ABO/Rh

Question 1

1. What are the 4 main blood types
   
   • Can you name the rare 5th blood type?
2. What is the most & least common blood types
3. What blood type is the universal donor and which is the universal acceptor?
4. What antibodies does each bloodtype make?
5. What antigen does each blood type present?
6. What genotypes give rise to each blood type?

Answer 1

1. The 5th rare form is the Bombay blood type, and they can only receive bombay blood. Very rare.

Question 2

Name the antibody class of most ABO isohemagglutinins

Answer 2

Predominantly IgM

Question 3

Bombay Bloodtype

1. What causes this?
2. What blood types look foreign to these people?
   
   • What kind of blood can a bombay phenotype person receive in a transfusion?

*Be sure to open the attachment/picture

Answer 3

1. Bombay people lack the transferase gene to put the final fucose sugar (red triangle) on the “core”.
   
   • Often mistyped as “O”
   • Make anti-A, anti-B, and anti-O … RUH ROH!
2. Unfortunately, because they can’t even make the H antigen, ALL blood (even O) looks foreign to Bombay type.
   
   • Can only receive bombay blood in a transfusion

Question 4

1. What is cross matching?
2. What would a positive test look like in the test tube?
3. What is the main risk of not properly crossmatching?

Answer 4

1. Performed prior to a blood transfusion in order to determine if the donor’s blood is compatible with the blood of an intended recipient
   
   • Compatibility is determined through matching of ABO and Rh antigen system, and/or by directly testing for the presence of antibodies against a sample of donor tissues or bloodA
2. Agglutination (cloudy) and hemolysis (red)– indicate antibody reactions with complement activation – Don’t use.
3. If pregnant, the baby will not be protected against the immune response

Question 5

Direct Cooomb’s Test

1. What diseases is it useful for?
2. What does it detect?
3. What question does it answer?

Answer 5

Direct Coomb’s test: Useful for Autoimmune hemolytic disorders

• Detect human Ig on the surface of RBCs
• Asks the question: Is there antibody already on the cells that I am interested in?

Question 6

Indirect Coomb’s Test

1. What is it used for?
2. What does it detect?
3. What question does it ask?

Answer 6

Indirect Coomb’s test: Useful for crossmatching before transfusion

• Detect human Ig in plasma
• Asks the question: Is there unexpected antibody to red cell antigens in the plasma of this recipient?

Question 7

What is a heterophile antibody?

Answer 7

1. An antibody that has the capacity to bind with multiple antigens (that are similar but not exactly the same)

Example:

Antibody that appears in someone infected with EBV (mononucleosis).

Happens to also react with horse red blood cells.

Since horses are easier to find than mono, you can do a quick and cheap test for mono (Monospot)

Question 8

What is Hemolytic Disease of the Newborn (HDN)?

a.k.a – erythoblastosis fetalis

Answer 8

HDN: Occurs in Rh(D)+ babies of Rh(D)- mothers

• Last trimester, and especially upon delivery, red cells from the baby enter mom’s circulation
• If mom is Rh(D)- and the baby is Rh(D)+, then she can make anti-Rh(D).
  
  • Cool, so baby is gone and doesn’t care
• BUT, if mom has another baby that is Rh(D)+, she’s got the memory to make those anti-Rh(D) antibodies and have them cross the placenta to kill baby’s blood cells
• Baby born jaundiced;High levels of bilirubin can cross BBB and damage the basal ganglia → cerebral palsy or death

Question 9

What treatment options to prevent HDN?

Answer 9

Preventable if @ time of first Rh(D)+ delivery you can give her IgG antibody to Rh(D). (RhoGAM)

• These opsonize with baby’s cells that cross the placental barrier and destroy them before she can mount a response
• Note: She is NOT made tolerant to Rh(D), so she MUST receive RhoGAM each pregnancy that she may be exposed to Rh(D)+ cells

Question 10

When can ABO hemolytic disease of the newborn can occur?

Answer 10

Some women make anti-ABO IgG (can cross the placenta via class switch) so they make IgG anti-A or anti-B

• Supposed to be IgM
  
  • If dad doesn’t have the same blood group as mom, then the baby may have a different blood group from mom
  • Similar HDN disease based upon the ABO group instead of the Rh
    
    • Mom’s anti-A or anti-B would then attack and kill the baby’s RBCs.

Question 11

What does direct vs indirect immunoflorescence test for?

Answer 11

Direct: tissue from patient is placed on slide, fluorescently-labelled antibodies to known bacterial antigens are poured onto tissue. This is a test for antigen.

Indirect: known bacteria are placed on slide, patient’s serum is poured onto bacteria, after washing, fluorescently-labelled goat anti-human Ig is poured over. This is a test for antibody.