Describe the serological differences between the A subgroups, focusing on the A1, A2, A3, and Ax subgroups*(is that and correctly?)
- A1: a-B Ab 4+
- A2: “ “ “ & a-A 1+
- A3: sometimes produce a-A
- Ax: sometimes produce a-A
- all contain a-B Ab
describe the bombay blood group
- not have ≥1 H allele = hh phenotype
- lack FUT1 (H) gene => not produce H Ag
= anti -H, -A, -B Abs
how do you screen blood from bombay blood group & what’s the suitable blood to give them
a) Ulex europeus (lectin) - clumps H Ag, so expect neg rxn bc no H Ag
b) transfused w/ blood from other Bombay individuals
describe the para-bombay blood group
- Weak / no expression of H Ag
- weak expression of A / B Ag if person produces A / B transferase
- Anti-H weaker than bombay
formation of para-bombay blood groups*(dc makes sense after revising)
- inactive FUT1 gene, active FUT2 (Se) gene => Type 1 H susbstance produced
Explain the difference between an adsorption and an elution
- Adsorption: plasma Ab bind to Ag on RBC (step 1)
- Elution: dissociate Ab (bound on Ag) measure the presence of the Ab bound
Describe how Dolichos biflorus (lectin) are used in transfusion science
Identify A2 subgroup bc
- A1 c = agglutinate
- A2 c = not agglutinate
What it meant by the term “mixed-field agglutination”?
- Some RBC not agglutinated
- Some RBC agglutinated
=> see 2 lines on CAT = 4+ & 0 rxn grades seen
how to distinguish A1 & A2 subgroups
Dolicous biflorus (anti-A1)
- A1 = pos
- A2 = neg
Ulex Europeus (anti-H)
- A1 = neg
- A2 =pos
Describe the general production of the ABO antigens
H, A, B Ag are produced by +ing single CHO residue (immunodominant) on precursor substance by glycosyltransferase
Type 2 precursor substance -> H Ag -> A or B Ag)
Describe the sugars on the type 2 precursor substance
- Gal (D-galactose)
- AcGlu (N-acetylglucosamine)
- Gal (D-galactose)
- Glu (Glucose)
RBC Membrane
Describe the production of the H antigens
a-2-L-fucosytransferase adds L-fucose to terminal D-galactose on T2 precursor substance 4. Gal –––– L-fucose 3. AcGlu 2. Gal 1. Glu RBC Membrane
Describe the production of the A antigens
a-3-N-acetylgalactosaminyltransferase adds N-acetyl-D-galactosamine to terminal D-galactose on H Ag
4. Gal ==== L-fucose + N-acetyl-D-galactosamine
3. AcGlu
2. Gal
1. Glu
RBC Membrane
*NOTE: A Ag hides H Ag
Describe the production of the B antigens
a-3-D-galactosyltransferase adds D-galactose to terminal D-galactose on H Ag 4. Gal ==== L-fucose + Gal 3. AcGlu 2. Gal 1. Glu RBC Membrane *NOTE: B Ag hides H Ag
how are A1 & A2 Ag differnet from each other
A1 = N-acetyl-D-galactosamine A2 = mutant a-3-N-acetyl-D-galactosaminyltransferase = less efficient in converting H Ag -> A Ag = less A Ag
difference b/w type 1 & type 2 precursor substance
Type 1: H Ag secreted from secretory tissues
Type 2: H Ag found only on RBC surface
difference b/w FUT1, FUT2, FUT3
- FUT1 (H) > encodes α-4-L-fucosyltransferase = H Ag
- FUT2 (Se) > encodes for a-1,4-fulcosyltransferase = secretory ABO Ag
- FUT3 (Le) > encodes for a-1,4-fucosyltransferase = Le Ag
What’s lectin?
- made from plant/seed extracts
- act like Abys - bind to specific sugar residues = agglutinate RBC
