Week 9 Flashcards
(23 cards)
What is an anomaly
When reactions dont fit the pattern
-discrepancy between the forward and reverse
-dont assign a blood group until the investigation is done
What do you do if you cant resolve the anomaly
give the patient group O red cells and AB plasma
What are subgroups of A
-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
What is the A2 phenotype
-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
What are lectins
-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
Rare A subgroups
-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
Weak ABO Antigen production
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
When is Antigen strength is depressed
Leukemia, Hodgkin’s Lymphoma, and
Hematopoietic stress
◦ Individuals have weaker A and B antigens (Bone Marrow Stressed)
When are Antigens not be detectable
Stomach or Pancreatic Cancer associated with
loss of ABO antigens
‘Acquired’ or pseudo-antigens
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
transfusion related antigen problems
- 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
When will you see Weak or Missing Antibodies
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
When will you see an Unexpected Antibody or Extra
Antibody Reaction
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
What would occur when Could be an antibody reacting with the antigens
on the RA/RB cells
◦ Test serum against a different lot of RA/RB cells
◦ Phenotype the RA/RB for the corresponding
antibody
◦ Use Screen cells for testing
What if you have a Cold Auto Antibody
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)
What is Rouleaux
- 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.
When you are investigating Anomalies what do you do
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
What are cold antibodies
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
how is the H antigen produced
H gene allows the L-fucose to be added to the terminal sugar of the precursor chain
how is the A antigen produced
A gene allows the N-acetyl-galactosamine to be added to the H substance,
how is the B antigen produced
B gene causes D-galactose to be added to the H substance,
producing B antigen
What is the Oh type
hh genotype
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
how do you know you have the Oh type - hh genotype and Bombay phenotype
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
