ABO Blood Group - Correct Answer Landsteiner
- we have Ab against Ag we lack
ABO Ab are naturally occurring, stimulated by nature
- low # until 3-6 months
Ag are codominant
each person has 2 Chr 9 with one allele
Genes at 3 loci control presence and location of the A,B,H Ag = ABO, Hh, Se
A and B genes encode glycosyltransferases which transfers immunodominant sugar specificity of A and B
Ag
Group O = silent allele (no gene product)
Hh and Se on CHr 19 closely links
h and se = amorph (no detectable product = no glycosyl tranferase)
H makes glycosyltransferase acting on 2 chains on H Ag on RBCs (H on RBC)
Se = glycosyltransferase acts on 1 chains H Ag in secretions ( H in secretions)
Bombay Phenotype - Correct Answer hh
no H Ag bc no transferase
will not react with Anti-A, Anti-B or Anti-H lectin
their serum will have anti-A, anti-B, anti-A,B and Anti-H
,only can be transfused by other Bombay phenotypes
O has most H substance then A then AB
A Subgroups - Correct Answer A subgroups
80% A1
20% A2
differentiating A1 and A2 based on Anti-A1 lectin Dolichos biflorus
A1 react with anti-A1
A2 cells do not
Weak A subgroups (<A2)
A3 = mix field agglutination with Anti-A
Ax = stronger reaction with anti-A,B then anti-A
weaker ones only detected by elution and adsorption of anti-A
Antibodies to A and B Ag - Correct Answer People A and B make IgM Ab (a little IgG)
People who are O make IgG (anti-A,B)
ABO sugars - Correct Answer H Ag L-fucose
A Ag N-acetylgalactosamine
B Ag D-galactose
,ABO testing - Correct Answer Forward
reagent = monoclonal Anti-A and Anti-B
give strong reactions (>/= 3+)
Reverse grouping
A1 cells and B cells (Rh neg)
(>/= 2+)-> weaker = serum problem
other reagents
Anti-A,B = subgroups classification or confirm group O units
A2 cells (resolve discrepancies)
Lectins
Anti-A1 D. biflorus
Anti-H Ulex europaeus
1/4 Discrepancy resolution (weak or missing Ag reactivity)-> cell grouping tests - Correct Answer
Subgroups of A and B =
- A3 subgroup mixed field pattern with
anti -A (from group O or B donors)
- Ax subgroup No agglutination with
anti-A from group B but agglutinate with anti-A,B from group O donors
- Ael subgroup not agglutinated by anti-A or anti-A,B -> Ag only shown with elution
- B subgroups very rare
leukemia and new borns may have weak expression of A / B Ag
Chimera = transfusion Hx
2/4 Discrepancy resolution (Extra Ag reactivity)
, cell grouping tests - Correct Answer Acquired B
- type as AB, but serum has anti-B
*assoc with GI tract disorder (transient)
Strength of reactivity weakened with decreased pH weakens reactivity (test at pH 6.0 acidified) ->
missing fwd group?
* test cells with monoclonal anti-B reagent (doesn't detect acquired B), autocontrol will also be negative
Pos DAT
- cells agglutinate spontaneously (Rh)
- can be ABO reagents if cold reactive Ab causing pos DAT
* wash cell
OR elute Ab from RBC with DTT
Contaminated cord blood sample
Wharton's Jelly causes
wash 3-4x with saline or get heel stick sample
Unwashed cell suspension
- patient Ab can cause reagent problems
- rouleaux
¾ Discrepancy Resolution (Weak or missing Ab reactivity) -> serum grouping tests - Correct Answer low
Ab levels (newborn or older)
Missing Ab (immunocompromised)
Chimera (tolerance to both cell pop')
Sub groups
A subgroups can type as O
Titre of anti-A higher than anti-B in group O = if weak reactivity with A1 you should investigate
- we have Ab against Ag we lack
ABO Ab are naturally occurring, stimulated by nature
- low # until 3-6 months
Ag are codominant
each person has 2 Chr 9 with one allele
Genes at 3 loci control presence and location of the A,B,H Ag = ABO, Hh, Se
A and B genes encode glycosyltransferases which transfers immunodominant sugar specificity of A and B
Ag
Group O = silent allele (no gene product)
Hh and Se on CHr 19 closely links
h and se = amorph (no detectable product = no glycosyl tranferase)
H makes glycosyltransferase acting on 2 chains on H Ag on RBCs (H on RBC)
Se = glycosyltransferase acts on 1 chains H Ag in secretions ( H in secretions)
Bombay Phenotype - Correct Answer hh
no H Ag bc no transferase
will not react with Anti-A, Anti-B or Anti-H lectin
their serum will have anti-A, anti-B, anti-A,B and Anti-H
,only can be transfused by other Bombay phenotypes
O has most H substance then A then AB
A Subgroups - Correct Answer A subgroups
80% A1
20% A2
differentiating A1 and A2 based on Anti-A1 lectin Dolichos biflorus
A1 react with anti-A1
A2 cells do not
Weak A subgroups (<A2)
A3 = mix field agglutination with Anti-A
Ax = stronger reaction with anti-A,B then anti-A
weaker ones only detected by elution and adsorption of anti-A
Antibodies to A and B Ag - Correct Answer People A and B make IgM Ab (a little IgG)
People who are O make IgG (anti-A,B)
ABO sugars - Correct Answer H Ag L-fucose
A Ag N-acetylgalactosamine
B Ag D-galactose
,ABO testing - Correct Answer Forward
reagent = monoclonal Anti-A and Anti-B
give strong reactions (>/= 3+)
Reverse grouping
A1 cells and B cells (Rh neg)
(>/= 2+)-> weaker = serum problem
other reagents
Anti-A,B = subgroups classification or confirm group O units
A2 cells (resolve discrepancies)
Lectins
Anti-A1 D. biflorus
Anti-H Ulex europaeus
1/4 Discrepancy resolution (weak or missing Ag reactivity)-> cell grouping tests - Correct Answer
Subgroups of A and B =
- A3 subgroup mixed field pattern with
anti -A (from group O or B donors)
- Ax subgroup No agglutination with
anti-A from group B but agglutinate with anti-A,B from group O donors
- Ael subgroup not agglutinated by anti-A or anti-A,B -> Ag only shown with elution
- B subgroups very rare
leukemia and new borns may have weak expression of A / B Ag
Chimera = transfusion Hx
2/4 Discrepancy resolution (Extra Ag reactivity)
, cell grouping tests - Correct Answer Acquired B
- type as AB, but serum has anti-B
*assoc with GI tract disorder (transient)
Strength of reactivity weakened with decreased pH weakens reactivity (test at pH 6.0 acidified) ->
missing fwd group?
* test cells with monoclonal anti-B reagent (doesn't detect acquired B), autocontrol will also be negative
Pos DAT
- cells agglutinate spontaneously (Rh)
- can be ABO reagents if cold reactive Ab causing pos DAT
* wash cell
OR elute Ab from RBC with DTT
Contaminated cord blood sample
Wharton's Jelly causes
wash 3-4x with saline or get heel stick sample
Unwashed cell suspension
- patient Ab can cause reagent problems
- rouleaux
¾ Discrepancy Resolution (Weak or missing Ab reactivity) -> serum grouping tests - Correct Answer low
Ab levels (newborn or older)
Missing Ab (immunocompromised)
Chimera (tolerance to both cell pop')
Sub groups
A subgroups can type as O
Titre of anti-A higher than anti-B in group O = if weak reactivity with A1 you should investigate
