Week 9

Question 1

What is an anomaly

Answer 1

When reactions dont fit the pattern
-discrepancy between the forward and reverse
-dont assign a blood group until the investigation is done

Question 2

What do you do if you cant resolve the anomaly

Answer 2

give the patient group O red cells and AB plasma

Question 3

What are subgroups of A

Answer 3

-differences in A gene that code for different amounts of enzyme
-fewer antigens on RBC membrane
-A1 antigens are branched and linear
-A antigens are linear
individuals have Anti B plasma

Question 4

What is the A2 phenotype

Answer 4

-Red cell membrane only has linear A antigens
-can produce Anti A1
-could have weaker reactions with Anti-A antisera in forward reactions
-pts have Anti A1 and Anti B in plasma

Give these patients Group O RBC PC or A1 negative PC

Question 5

What are lectins

Answer 5

-seed extracts that agglutinate with human red blood cells
-from plants
-Anti-A1 Dolichos biflorus - will react with A1 cells but not A2 NOT THE SAME AS HUMAN ANTI A1

Anti H - ulex europaeus

Question 6

Rare A subgroups

Answer 6

-weak or no reactions with Anti A or Anti A, B reagents
-no agglutination with Anti A1 lectin
-presence of absence of Anti A1 in serum
-strong agglutination with Anti H
-Adsorption and elution studies
-do molecular to confirm testing

Question 7

Weak ABO Antigen production

Answer 7

ABO antigens are not NOT WELL DEVELOPED AT BIRTH
-Enzymes that transfer carbohydrate sugars are not well developed in newborns
-Lower levels of enzymes and fewer antigens on
red cells
-can cause weaker reactions
-Monoclonal antisera are strong which make the forward reaction visible

Question 8

When is Antigen strength is depressed

Answer 8

Leukemia, Hodgkin’s Lymphoma, and
Hematopoietic stress
◦ Individuals have weaker A and B antigens (Bone Marrow Stressed)

Question 9

When are Antigens not be detectable

Answer 9

Stomach or Pancreatic Cancer associated with
loss of ABO antigens

Question 10

‘Acquired’ or pseudo-antigens

Answer 10

Acquired B’ antigen was found in Group A patients with lower intestinal tract disorders like cancer, infection, or obstruction.
-Some A antigens are altered and become more like the B antigen and react with Anti-B Antisera
- Anti-B still detectable in the patient’s serum

Question 11

transfusion related antigen problems

Answer 11

• in emergency group O blood can be given to group A, B , AB and then the pts blood will contain O RBC mixed with pt blood
  -youll see mixed field (strong positive reaction with patient cells and some un-agglutinated O cells in the background)
  -Patients with Bone Marrow Transplants can exhibit Mixed
  mixed-field reaction

Question 12

When will you see Weak or Missing Antibodies

Answer 12

Age (Babies don’t make antibodies until four months of age, and Elderly’s immune system produces less antibodies)- Wartons Jelly can interfere
* Disease (Immune disorders such as Hypogammaglobulinemia and
Agammaglobulinemia)
* Immunosuppressive Drugs

Question 13

When will you see an Unexpected Antibody or Extra
Antibody Reaction

Answer 13

Subgroup of A (A2 produce Anti A1 but can have Anti A1 and Anti B in the plasma)
* Allo Antibodies (Reaction with RA/RB reagents)
* Auto Antibodies (Cold Agglutinins since the optimal temperature is Room Temperature)
* Rouleaux

Question 14

What would occur when Could be an antibody reacting with the antigens
on the RA/RB cells

Answer 14

◦ Test serum against a different lot of RA/RB cells
◦ Phenotype the RA/RB for the corresponding
antibody
◦ Use Screen cells for testing

Question 15

What if you have a Cold Auto Antibody

Answer 15

set up a cold panel to determine what is causing the extra reaction
◦ prewarm technique to avoid interference of reactions (if found to be clinically insignificant)

Question 16

What is Rouleaux

Answer 16

• looks like agglutination in tubes
  -look MICROSCOPICALLY
  -stack of coins
  -do saline replacement
  -rouleaux will disperse and agglutination will stay

it has : Increased protein, seen patients with MM.

Question 17

When you are investigating Anomalies what do you do

Answer 17

1.Repeat sample
2. Check all reagents and samples
3. Retrieve patient history and diagnosis
4. Adjust test conditions to strengthen reactions
5. Run additional tests using other reagent cells or antisera
6 Collection of new sample

Question 18

What are cold antibodies

Answer 18

insignificant and would be missed by MTS and Capture R methods
-you would not detect a cold antibody in group O blood because it would be masked by ABO antibodies
-if an allo antibody is detected , it must be worked up

Question 19

how is the H antigen produced

Answer 19

H gene allows the L-fucose to be added to the terminal sugar of the precursor chain

Question 20

how is the A antigen produced

Answer 20

A gene allows the N-acetyl-galactosamine to be added to the H substance,

Question 21

how is the B antigen produced

Answer 21

B gene causes D-galactose to be added to the H substance,
producing B antigen

Question 22

What is the Oh type

hh genotype

Answer 22

No H gene (hh genotype) means no H, A, or B antigens can be produced

Allele is H = so no enzyme produced
-Forward types as a Group O because there are no reactions with Anti-A, Anti-B and Anti-A,B but plasma reacts with both A1 and B cells.
-Serum contains Anti-A, Anti-B, Anti-A,B and Anti-H
-Naturally occurring just as they are in other ABO types
-Anti H is IgM so it binds complement and has a big temperature range
-reacts with Antibody screens and panel cells in both MTS or solid phase method
-must be transfused with a Bombay donor

Question 23

how do you know you have the Oh type - hh genotype and Bombay phenotype

Answer 23

 All screening cells and panel cells would react with the plasma at RT, 37˚C, and IAT
 Only the Auto control would be negative
 Use the Lectin Anti- H, Ulex europaeus to type the cells
 Find hh individuals and request them to donate and freeze their blood regularly.
 Directed Donation
 If the patient is healthy, have them freeze their blood