(P) ABO BGS Flashcards
The detection of ABO incompatibility between the donor and the recipient is the basis or foundation of _________________________
.
Pre-transfusion testing
The transfusion of ABO-incompatible blood will result to ____________ of donor RBC which would lead to very severe transfusion reaction and could be fatal and lead to death.
lysis
What is the leading cause of death due to transfusion
TRALI (transfusion related acute lung injury)
- 1st person to perform both the forward and reverse method of blood typing
- discovered ABO in 1901
Karl Landsteiner
- most important blood group systems in terms of blood transfusion
- 1st and simplest human BGS known
*
ABO BGS
The only blood group system in which the reciprocal antibodies are consistently and predictably present in the sera of normal people whose RBCs lack the corresponding antigen(s)
ABO BGS
This is the rule wherein the reciprocal antibodies are consistently and predictably present in the sera of normal people whose RBCs lack the corresponding antigen(s)
Landsteiner’s rule
what is the only BGS that have the Landsteiner’s rule
ABO
ABO genes are located on ?
chromosome 9
in what manner are ABO genes inherited?
codominant
Which ABO gene is considered an amorph / recessive gene
O
a silent gene wherein no detectable Ag is produced in response to the inheritance of this gene.
amorph gene
O gene can only be detected when performing ______________
genotyping
when we do blood typing in the laboratory, we are doing _____________
a. genotyping
b. phenotyping
b. phenotyping
- the A/B/O gene inherited codes for the production of ____________
- this adds immunodominant sugars to a basic precursor substance (paragloboside) to be added the the Red cell
Glycosyltransferases
Which type of paragloboside?
- β 1→3 linkage: #1C of D-galactose connects to #3 C of Nacetylglucosamine
Type 1 Precursor chain
Which type of paragloboside?
β 1→4 linkage: #1 C of D-galactose connects to #4 C of Nacetylglucosamine
Type 2 precursor chain
Development of A and B antigens
- detected on embryonic red cells as early as _______
- A and B antigens are detectable in the red cells as early as _______ week of fetal life.
- Expression is fully developed by __________
- five weeks after conception
- 37th week of fetal life
- 2 to 4 years of age
What is the pre requisite for the production of glucosyltransferases to add immunodominant sugars to a basic precursor substance
H gene must first attach to its own immunodominant sugar to the paragloboside
matching type
a. H gene
b. A gene
c. B gene
- α-3-Nacetylgalactosaminyl transferase
- α-2-Lfucosyltransferase
- α-3-D’Galactosyltransferase
- B
- A
- C
Matching type
a. H gene
b. A gene
c. B gene
- D’Galactosyltransferase
2.L-fucose - N-acetyl-D’Galactosamine
- C
- A
- B
These are the 0.01 of individuals that do not have the H gene
- they are unable to express their own antigens on the red cells
- they can transmit normal A and B gene to their offspring
Bombay blood group
Explain how H gene influences A and B antigenic expression
- H gene codes for fucosyl transferase production -> catalyzes the addition of L-fucose attached on to Type 2 precursor chain
- A and B specified products can act to add sugars to the chains that carry H
which ABO gene elicits a higher concentration of transferase?
- can effectively convert H gene to its own antigen
A gene
which ABO gene competes more efficiently for the H substance?
B gene
which ABO gene does not produce an active form of transferase
O gene
Which ABO group has the greatest amount of H antigen on the red cells
O gene
O > A2 > B > A2B > A1 > A1B
Which has the least amount of H antigen
A1B
Hello just please review the genotypes and phenotypes as well as the punnet square
me thinks alam niyo naman na ‘yan
What are the 2 genes that make up the H gene
dominant H and h (silent genus)
serves as the precursor molecule on which A and B antigens are built/ can attach their own sugars
H antigen (L-fucoseimmunodominant sugar)
- the reagent used to detect H antigen
ULEX EUROPAEUS (Anti-H lectin)
Why are groups A. AB, and B that produce anti-H clinically insignificant ?
(i hope this made sense my brain is fried)
they react at room temperature
Therefore tethers are higher chances for blood transfusion reactions to take place
Which is more significant?
a. IgM
b. IgG
b
- IgM - optimum reactivity is RT so it is clinically insignificant
*IgG - more significant because they react at body temperature and can produce transfusion reactions when transfused
Para-Bombay phenotypes: Ah, Bh, ABh) virtually always reacts at room temperature
IgM
________________________ have no A, B, or H antigen, forms a potent clinically significant anti-H which reacts well over a wide thermal range and with all RBCs, except those of the same Oh people.
Rare Oh (hh) phenotype
T or F
Bombay phenotype has all antibodies, it can agglutinate all the red cells
T
Why is the Oh phenotype called “BOMBAY”
it was first discovered in Bombay, India in 1952
This phenotype occurs when an individual inherits two (2) silent state hh genes in a homozygous state.
They lack the H gene necessary for H antigen production
- these cannot attach their own sugars as they don’t have the H antigen
Bombay phenotype
T or F
people with the Bombay phenotype have potent A, B, AB, and H antigens
F (potent anti-A, anti-B, anti-A B and Anti-H which is most clinically significant)
CONFIRMATORY TESTING FOR Oh
what is the expected result of a patient with Anti-H?
no agglutination = positive result for Bombay
CONFIRMATORY TESTING FOR Oh
Patient’s serum (will / will not) agglutinate Oh cells
will NOT
regulates the formation of H antigen and subsequently, of A and B antigens in body fluids, secretion (saliva, tears, urine, digestive juices, bile, milk, amniotic fluid, etc.)
This also useful since we use this in determining or confirming the blood type of a patient, especially when there are discrepancies. This done by performing the Saliva test.
Sese system
Sese codes for production of ________________________ that modifies Type-1 precursor to form H substance, modified to A & B substance, if corresponding gene is present, in saliva and other body fluids
ά-2-Lfucosyltransferase
a. secretor
b. non secretor
- Inherits SeSe and Sese
- The gene se, is an amorph, like the O gene
- There can be no Se when se is present on both chromosomes
- Presence of A, B, and/or H substances in the saliva
- A
- B
- B
- A
a. secretor
b. non secretor
- Absence of A, B, and H substances
- inherits sese
- “silent gene”
- B
- B
- B
T or F
secretor genes are directly linked to the ABO locus, they are inherited together
F (The secretor genes are not linked to the ABO locus, they are inherited independently)
this gene produces a weaker than normal red cell antigen (decreased antigenic sites) in some cases because of a difference in the transferase sites
variant gene
a. A1 cell
b. A2 cell
- Accounts for 80% of the population
- Accounts for 20% of the population
- There are some H antigen remaining that is not converted into A antigen
- Has only A antigen
- Has both A1 and A antigen
- A
- B
- B
- B
- A
a. A1 cell
b. A2 cell
- the transferase this produces is more efficient in converting H to A
- There are some H antigen remaining that is not converted into A antigen
- POSITIVE to anti-H lectin
- NEGATIVE to anti-H lectin
- almost all H are used up and no exposed H antigen in red cell
- A
- B
- B
4.A - A
a. A1 cell
b. A2 cell
- Has a stronger reaction during direct typing
- Have a weaker reaction due to crowded antigenic sites
- Positive for anti-A1 lectin, negative for Anti-H
- A
- B
- A
What is the immunodominant sugar in A1 and A2?
N-acetyl-D-galactosamine
OTHER SUBGROUPS A
Characterized by mixed-field agglutination (small agglutinates within predominantly unagglutinated cells)
A3
OTHER SUBGROUPS A
- not agglutinated by anti-a reagent
- agglutinated by anti-a, b
- antigenic sites (4000/RBC)
- Produce anti-A1
Ax
OTHER SUBGROUPS A
- Mixed filled reaction
- only 10% of RBCs agglutinate
- antigenic sites (3500/RBC)
- some w/ anti-A1
- with possible variants (Afinn, Abantu)
Aend
OTHER SUBGROUPS A
* not agglutinated or weakly agglutinated by anti-A and anti-A, B
* antigenic sites (200-1900/RBC)
* does not produce Anti-A1
Am
OTHER SUBGROUPS A
*Not agglutinated by anti-A and anti-A,B
* Usually do not produce anti-A1
*germline mutation of A gene within the family
Ay
OTHER SUBGROUPS A
- not agglutinated by anti-a and anti-a, b
*usually produce anti-A1 and anti-A
Ael
SUBGROUPS OF B
- characterized by mixed-field agglutination with anti-B and anti-A,B
- produce anti-b
*most frequent weak b phenotype
B3
SUBGROUPS OF B
- weak agglutination with anti-b and anti-a, b
*produce weak anti-b
Bx
SUBGROUPS of B
- unagglutinated with anti-B and anti-A,B
- formed as a result of reduced activity of B enzyme in hematopoietic tissue
- Transforms to normal B phenotype if incubated with normal B plasma plus uracil diphosphate (UDP)-galactose
*No anti-B present in the serum
*product of interacting modifying genes closely linked to ABO locus - frequent in Japan
Bm
SUBGROUPS OF B
- unagglutinated by anti-B and anti-A,B
*unique mutation in exon 7 of B gene
*May have weak anti-B in serum
Bel
Antibodies are generally too low for detection until infants are _____________-
3-6 mos old
why cant babies be reversed type?
- Most or all antibodies present are IgG from maternal origin = test will be INVALID
- Antibodies generally too low for detection for ages up to less than 6 months of age
when does antibody production peak?
5-10 years old
can the elderly be reversed typed?
Elderly people usually have lower levels of anti-A and antiB; therefore, antibodies may be undetectable in the reverse grouping.
GENERAL CHARACTERISTICS OF ANTIBODIES TO ABO
What type of antibodies are ABO predominantly are?
IgM
GENERAL CHARACTERISTICS OF ANTIBODIES TO ABO
these antibodies are __________________ because they are produced without any exposure to RBCs
naturally occuring
GENERAL CHARACTERISTICS OF ANTIBODIES TO ABO
ABO antibodies produce ________________ reactions during ABO testing
strong direct agglutination
GENERAL CHARACTERISTICS OF ANTIBODIES TO ABO
T or F
Agglutinates saline suspended platelets, no additional reagents needed but still has a strong reaction
F (platelets -> red cells)
GENERAL CHARACTERISTICS OF ANTIBODIES TO ABO
may produce hemolysis in:
a. in vivo
b. in vitro
c. both
d. neither
c
ANTIBODIES TO ABO MATCHING TYPE (some items may have more than one answer)
a. anti-a
b. anti-b
c. anti-a,b
d. none
- blood group A
- blood group B
- blood group AB
- blood group O
- B
- A
- D
- A,B,C
useful in determining the subgroups and also during the blood typing of babies because they still have very weak antigens and antibodies
Anti-A,B or O serum
- Test unknown cells with known antisera OR detecting RBC antigens with known antisera
Sample used: RBC suspension
*It is performed for the detection of antigens
Reagents used: Commercially prepared antisera
red cell / forward / direct typing
what color is the commercially prepared antisera
anti-A =
anti-B =
Anti-A (BLUE)
Anti-B (YELLOW)
*Test unknown serum/plasma with known RBCs of known antigens OR detecting antibodies in the serum/plasma using known antigens
*Sample used: Serum/plasma (it is where antibodies are found)
* It is performed for the detection of antibodies
SERUM/ REVERSE/ INDIRECT TYPING
a. False positive
b. False negative
- When agglutination occurs not because the antigen is present, but because cells may already be clumped
2.One in which the cells are not clumped because there are too many cells or not enough reagent.
- You cannot determine or use the optimum ratio and you cannot avoid zonal reaction in slide method because we do not prepare red cell suspension
- In the slide method, whole blood or capillary blood are used.
- Unlike in tube method, an RBC suspension 2-5% is prepared to prevent zonal reaction
- Excess antibody will lead to false negative (PROZONE effect)\
- False positive
2-5 false negative - false positive
at what temps should antisera be stored at?
2-8 deg celsius
in performing quality testing, what should the reaction be before employing to the patient?
+3 or +4
What might be the cause of turbid antisera?
bacterial contamination
the slide is tilted back and forth for how long to observe for agglutination of the RBCs?
forward typing
if an RBC contains the A antigen, the red blood cells will be agglutinated by anti-A which indicates a
positive reacton
If an RBC does not have the A antigen, there will be NO clumping indicating a
negative reaction
If an RBC contains the B antigen, the red blood cells will be agglutinated by anti-A indicating
positive reaction
f an RBC does not have the B antigen, there will be NO clumping by anti-B indicating a
negative reaction
Interpreted as negative both for anti-A and anti-B, thus it is type _______
o
Both positive in anti-A and anti-B, thus it is type
AB
If you are Type A, what is the antigen and antibody present on your red cell?
antigen A and antibody B
FORWARD TYPING
O
anti-A:
anti-B:
anti-A: -
anti-B: -
FORWARD TYPING
A
anti-A:
anti-B:
anti-A: +
anti-B: -
FORWARD TYPING
B
anti-A:
anti-B:
anti-A: -
anti-B: +
FORWARD TYPING
AB
anti-A:
anti-B:
anti-A: -
anti-B: -
REVERSE TYPING
O
anti-A:
anti-B:
anti-A: +
anti-B: +
REVERSE TYPING
A
anti-A:
anti-B:
anti-A: +
anti-B: -
REVERSE TYPING
B
anti-A:
anti-B:
anti-A: +
anti-B: -
REVERSE TYPING
AB
anti-A:
anti-B:
anti-A: -
anti-B: -
GRADING OF REACTION TUBE METHOD
MATCHING TYPE
a. 4+
b. 3+
c. 2+
d. 1+
- One solid agglutinate, no free cells, clear supernatant fluid (macroscopic)
- Several large agglutinates, few free cells, clear supernatant (macroscopic)
- Medium-sized agglutinates, some free cells, clear supernatant (macroscopic)
- Small agglutinates, many free cells, turbid background reddish supernatant (macroscopic & microscopic reading)
- A
- B
- C
- D
GRADING OF REACTION TUBE METHOD
MATCHING TYPE
a. 1w
b. MF
c. H
d. PH
1, Partial hemolysis, some RBCs remain
2. complete hemolysis
3. Mixed-field, few isolated agglutinates with large areas of unagglutinated cells, reddish supernatant (microscopic)
4. Very small/tiny agglutinates (microscopic), turbid background, reddish supernatant (microscopic)
5. Negative, no agglutination, smooth suspension of cells
- D
- C
- B
- A
- A
what is the sample used for:
tube method
slide method
tube = 5% red cell suspension
slide = whole blood
Identify the method:
Principle: Sequestration of agglutinated cells in polyacrylamide gel
gel method
what is used in gel method instead of a tube or slide?
gel card
what should the result for control be in the gel method?
always negative
What is the charge of sodium in the gel card?
neutral
GRADING OF REACTION FOR GEL METHOD
a. 4+
b. 3+
c. 2+
d. 1+
e. 0
- Red cell agglutinates through length of column
- Solid band of red cells on the top of the gel
- RBC agglutinates mainly in lower half of gel column with some unagglutinated red cells pelleted at the bottom
- Agglutinated red cells in the upper half of the gel column
- Negative, pellet at the bottom and no agglutinates in the matrix of the gel column
- C
- A
- D
- B
5.E
Any deviation from the expected pattern of antigen on the cell and the opposite antibody in the serum
ABO Discrepancies
