Chapter 6: The ABO Blood Group System (P) Flashcards
What is the most important blood grp system among all blood grps in transfusion practice?
The ABO system
What is the characteristic of ABO blood grp system?
It is the only blood grp system in w/c people have Abs in their serum to Ags that are absent from their RBCs
What is the result since Abs are present in the ABO blood grp system?
Due to these Abs, transfusion of incompatible ABO type may result in immediate lysis of donor’s RBCs
What is the leading cause of death that is still present until today?
Transfusion of wrong ABO grps w/c results in hemolytic transfusion rxn fatalities reported by FDA
What are the processes or principles present under routine ABO testing?
1) Forward grouping
2) Reverse grouping
What is the principle of forward grouping?
The pt’s RBCs w/ commercial antisera
What is the principle of reverse grouping?
The pt’s serum w/ commercial RBCs
What are the routine rgnts used for ABO testing (in forward typing)?
1) Anti-A
2) Anti-B
3) Anti-D
4) Rh Control
What are the routine rgnts used for ABO testing (in reverse typing)?
1) A1 cells
2) B cells
3) A2 cells: also available but not routinely used
*What are the concepts for routine ABO testing?
1) Ags are present on the RBCs
2) Abs are present in the pt’s plasma / serum
Answer the ff questions w/ regards to ABO frequencies in the given blood grp:
1) What is the frequency of ABO for white individuals?
2) What is the frequency of ABO for black individuals?
Given blood grp: O
1) 45%
2) 50%
Answer the ff questions w/ regards to ABO frequencies in the given blood grp:
1) What is the frequency of ABO for white individuals?
2) What is the frequency of ABO for black individuals?
Given blood grp: A
1) 40%
2) 26%
Answer the ff questions w/ regards to ABO frequencies in the given blood grp:
1) What is the frequency of ABO for white individuals?
2) What is the frequency of ABO for black individuals?
Given blood grp: B
1) 11%
2) 20%
Answer the ff questions w/ regards to ABO frequencies in the given blood grp:
1) What is the frequency of ABO for white individuals?
2) What is the frequency of ABO for black individuals?
Given blood grp: AB
1) 4%
2) 4%
What is the relationship bet forward and reverse typing?
Forward typing is inversely related to reverse typing
Is reverse typing performed in infants? Why or why not?
No, because they do not have ABO Abs at birth
Since reverse typing is not performed to infants, what is only performed?
Forward typing
In reverse typing for infants, what is the sx used?
Cord blood
Most Abs present in the cord blood serum are from whom?
From the mother (maternal)
Reciprocal ABO Abs are what?
These are naturally occurring Abs
*When are reciprocal ABO Abs fully developed?
These are fully developed at 3 - 6 mos after birth
*Postulated role of bacteria
*What is the predominant Ig present in ABO Abs?
IgM (pentamer)
What is the main Ig present in anti-A (from a B person) and anti-B (from an A person)?
IgM
Even if IgM is mainly present in anti-A and anti-B, what is the other Ig present in small quantities in anti-A and anti-B?
Small quantities of IgG
*What are the Abs produced by O persons?
1) Anti-A
2) Anti-B
3) Anti-A,B
What Ig is anti-A,B?
IgG
True or False
Anti-A,B is a combination of anti-A and anti-B
False, because anti-A,B is not a combination of anti-A and anti-B
*What is the characteristic of anti-A,B?
It is a separate “cross-reacting” Ab
*What are the fxns of ABO Abs?
1) To activate complement
2) To produce strong direct agglutination rxns
*At what temp are ABO Abs present (or stable?)?
Room temp (22 DC) or colder
*What are the characteristics of the rgnts used in routine ABO testing?
1) Rgnt anti-A is used
2) Rgnt anti-B is used
3) Rgnt anti-A,B is used
4) Can be monoclonal antisera
5) Can be polyclonal antisera
6) Considered in routine blood bank testing
Is rgnt anti-A,B routinely used? Why or why not?
It is not routinely used because commercial, monoclonal anti-A and anti-B can detect most weak A and B Ags
What is the contribution of the work of Bernstein?
It is the 1st to demonstrate inheritance of ABO gene - one from both parents
When is the work of Bernstein presented?
1924
*What are the characteristics of inheritance by Mendelian genetics?
1) Codominant expression
2) O gene is considered an amorph
3) O phenotype can only be produced by 2 O genes (OO)
4) Phenotype vs Genotype
Why is O gene considered an amorph?
Because there is no detectable Ag produced by the inheritance of this gene
What is the corresponding phenotype of the given genotype?
Given genotype: A1A1
A1
What is the corresponding phenotype of the given genotype?
Given genotype: A1A2
A1
What is the corresponding phenotype of the given genotype?
Given genotype: A1O
A1
What is the corresponding phenotype of the given genotype?
Given genotype: A2A2
A2
What is the corresponding phenotype of the given genotype?
Given genotype: A2O
A2
What is the corresponding phenotype of the given genotype?
Given genotype: A1B
A1B
What is the corresponding phenotype of the given genotype?
Given genotype: A2B
A2B
What is the corresponding phenotype of the given genotype?
Given genotype: OO
O
What is the corresponding phenotype of the given genotype?
Given genotype: BB
B
What is the corresponding phenotype of the given genotype?
Given genotype: BO
B
ABH Ag formation results from what?
It results from the interaction of genes at 3 separate loci (ABO, Hh, and Se)
*What is the characteristic of the genes that interact w/c results to ABH Ag formation?
These genes do not code for production of Ags but rather to produce sp glycosyltransferases that add sugars to a basic precursor substance
What is the characteristic of H Ag?
It is the precursor structure on w/c the A and B Ags are made
Where are H and Se genes present?
These are present on chromosome 19
What is the relationship bet H and Se genes?
These are closely linked
Se gene are inherited to form what?
To form the ABO Ags in secretions
*At what age grp are A, B, and H Ags produced?
In fetal and adult life
What is the percentage of Ags present in the RBCs of newborns in comparison to those found on adult RBCs?
25 - 50% of Ags of those that are found in adult RBCs
What is the result since RBCs of newborns carry 25 - 50% of Ags to those found on adult RBCs?
Newborn rxns in the forward typing are weaker than those in adults
When are ABO Ags fully expressed?
These are fully expressed at 2 - 4 yrs of age
Are ABO Abs present until 3 - 6 mos?
No, these are not present until 3 - 6 mos
Immunodominant sugars confer what?
These confer blood grp specificity
What is the immunodominant sugar present to the given gene and Ag?
Given gene and Ag: H
L-fucose
What is the immunodominant sugar present to the given gene and Ag?
Given gene and Ag: A
N-acetyl-D-galactosamine
What is the immunodominant sugar present to the given gene and Ag?
Given gene and Ag: B
D-galactose
Where is ABO gene located?
It is located on chromosome 9
What is the composition of ABO gene?
It consists of 7 exons
*What is present at the ABO locus?
Diversity
What are integral parts of the membranes of various cells?
ABH Ags
Where can ABH-soluble Ags be found?
These can be found in all body secretions
*ABH-soluble Ags w/c are present in secretions is dependent on what?
These are dependent on ABO and secretor genes inherited
*Are nonsecretors possible to be dependent on ABO and secretor genes inherited?
Yes
What are ABO subgrps?
These are phenotypes that show weaker variable serological reactivity w/ the commonly used human polyclonal anti-A, anti-B, and anti-A,B rgnts
What type of rgnts are used routinely for ABO subgrps?
Monoclonal typing rgnts
Who 1st described A subgrps?
von Dungen
When are A subgrps 1st described?
1911
What are the A subgrps?
1) A1 subgrp
2) A2 subgrp
At what aspects are A1 and A2 different?
1) Quantitative
2) Qualitative
Which is more generally common bet A subgrps and B subgrps?
A subgrps generally are more common > B subgrps
*What is present among A subgrps?
Differences in conversion of H precursor substance
*What are present at the ABO locus?
Effects of polymorphism
*What is the result if forward grping rgnt anti-A is used?
It strongly agglutinates both A1 and A2 phenotypes
What are the fxns of anti-A1 lectin rgnt (in connection w/ A subgrps)?
1) It is used in the differentiation of A1 and A2 phenotypes
2) It agglutinates A1 (or A1B) cells but does not agglutinate A2 (or A2B cells)
What are the exs of lectins used in BB?
1) Dolichos biflorus
2) Bandeiraea simplicifolia
3) Ulex europaeus
What is the fxn of Dolichos biflorus?
It agglutinates A1 or A1B
What is the fxn of Bandeiraea simplicifolia?
It agglutinates B cells
What is the fxn of Ulex europaeus?
It agglutinates O cells (H specificity) and other ABO blood grps depending on the amt of H Ag available
*Do the concentration of H Ag vary among blood grps?
Yes
What is occasionally found in the serum?
Anti-H
*What are the characteristics of H Ag?
1) It is a naturally occurring IgM cold agglutinin that reacts best below room temp
2) It can produce possible problems in Ab screening procedures
3) It can be detected via the use of anti-H lectin
*What is the frequency of appearance of subgrps weaker than A2?
These occur infrequently
*How are weak A subgrps most often recognized?
These are most often recognized through an ABO discrepancy (unexpected rxns in the forward and reverse grping)
*varying expression of 4 characteristics
Weak A subgrps can be distinguished as what?
1) A3
2) Ax
3) Aend
4) Am
5) Ay
6) Ael
What are the characteristics of weak B subgrps?
1) These are very rare and less frequent > A subgrps
2) These are usually recognized by variations in the strength of the rxn using anti-B and anti-A,B antisera
3) These are the result of alternate alleles at the B locus
*How many criteria are used for differentiation of weak B phenotypes?
5
What can be used to characterize B subgrps as weak B subgrps?
Serologic techniques
*What are the ff categories of B subgrps w/c are considered as weak B subgrps?
1) B3
2) Bx
3) Bm
4) Bel
The Bombay phenotype is denoted as what?
Oh
Who 1st reported the Bombay phenotype?
Bhende
When did Bhende 1st reported the Bombay phenotype?
1952
When did Bhende 1st reported the Bombay phenotype?
In Bombay, India
What is the characteristic of hh genotype?
It is a very rare genotype
How can genotype hh be produced?
Via the inheritance of a double dose of the h gene
What are the characteristics of the Bombay phenotype?
1) It has no H Ag made
2) ABO genes can’t be expressed
3) ABH genes can’t be formed
4) RBCs are devoid of normal ABH Ags
5) It fails to react w/ anti-A, anti-B, and anti-H
6) It is an IgM Ab
If only anti-A and anti-B antisera are used in RBC testing, the Bombay would phenotype as what blood grp?
O blood grp
Where is anti-H occasionally found?
In the serum of A1 and A1B individuals
The Bombay anti-H can often be potent and reacts strongly at what temp?
37 DC
What are the fxns of the Bombay phenotype?
1) It can bind complement
2) It can cause RBC lysis
True or False
Considerations for transfusions for Bombay phenotype must be present
True
Who is/are the pt/s that can donate blood to a pt w/ Bombay phenotype?
Blood w/ Bombay phenotype is the only blood that is compatible
Why should only a Bombay (donor) can donate blood to another Bombay (recipient)?
Because underlying molecular defect of the Bombay phenotype may be present
What are the characteristics of Para-Bombay phenotypes?
1) These are rare phenotypes
2) RBCs are completely devoid of H Ags or
3) Small amts of H Ag are present
*True or False
ABH Ags and leukemias are associated
True
Leukemias that are associated w/ ABH Ags demonstrates what?
Hypogammaglobulinemia
Provide an ex of leukemia w/c is associated w/ ABH Ags
Chronic lymphocytic leukemia (or Chronic lymphoid leukemia) (CLL)
*What are the diseases that can be present in ABH Ags and Abs in disease?
1) Other leukemias w/ chromosome 9 translocations
2) Any hemolytic disease inducing stress hematopoiesis (ex. thalassemia)
3) Acquired B phenomenon in grp A1 individuals
What are the causes of the occurrence of unexpected rxns in the forward and reverse grping?
1) Problems w/ the pt’s serum
2) Problems w/ the pt’s RCs
3) Problems w/ both the serum and cells
What is affected if problems w/ the pt’s serum (as cause of occurrence of unexpected rxns in the forward and reverse grping) are present?
Reverse grping
What is affected if problems w/ the pt’s RCs (as cause of occurrence of unexpected rxns in the forward and reverse grping) are present?
Forward grping
What is affected if problems w/ both the pt’s serum and cells (as cause of occurrence of unexpected rxns in the forward and reverse grping) are present?
Forward and reverse grping
What is the characteristic of ABO discrepancies?
These can appear as extra (+) or weak / missing rxns
What must be done to ABO discrepancies if these are present prior to reporting a pt or donor’s ABO grp?
These must be resolved
What are the resolutions that can be done to common grp II discrepancies?
1) Enhancing weakly reacting Ags w/ room temp incubation
2) Pretreatment of RBCs w/ enzymes
3) In connection to acquired B Ag
What are the diff categories of ABO discrepancies?
1) Grp I discrepancies
2) Grp II discrepancies
3) Grp III discrepancies
4) Grp IV discrepancies
What are the resolutions for common grp III discrepancies?
1) In connection to effects of rouleaux
2) In connection to effects of Wharton’s jelly
What are the resolutions for common grp IV discrepancies?
1) In terms for consideration of cold autoAbs
2) The pt’s RBCs can be tested w/ Dolichos biflorus to confirm the presence of an ABO subgrp
3) Unexpected alloAbs in the pt’s serum other than ABO isoagglutinins may cause a discrepancy in the reverse grping
