To know:
the different blood group types
their antigens and antibodies
Clinical significance of the antibodies
The mode of inheritance
The biochemistry of their synthesis
Inter group donors and recipient
How ABO grouping is done using the different
methods available
Until 1900, all blood were thought to be the
same
Led to frequently fatal transfusions of animal
blood into humans and hazardous transfusions of
blood between people
Human blood is not the same
Peoplebelong to different blood groups,
depending upon the surface markers found on
the red blood cell
Allauthenticated antigens belong to one of
the following classifications:
System
Collection (200 collections)
Low incidence series (700 collections)
High incidence series (901 collections)
Blood group systems:
• ABO blood group system
• Rh blood group system
• Other blood group systems
Discovered by Karl Landsteiner in 1900
Mostimportant system in relation to transfusion or
organ transplantation medicine
ABOantigens are the most immunogenic of all the
blood group antigens
Itconsist of three allelemorphic genes ABO
encoded by one genetic locus ABO locus
There are four blood groups in this system A, B,
AB, O
Consist of antigens and antibodies
Phenotypes are determined by presence or
absence of two antigens
ABO antigens are membrane carbohydrate ‘sugar’
structures
ABO antigens are present even at 1st trimester
Antibodiesare present in serum/plasma and are
usually IgM. IgG also exist
They are naturally occurring in adults and older
children
Undernormal conditions, if an antigen (Ag) is
present on a patients red blood cells the
corresponding antibody (Ab) will NOT be present in
the patients plasma
Bloodgroup A individuals have A antigen and anti-
B antibodies
Group B individuals have B antigen and anti-
A antibodies
Group O has no antigens and A,B antibodies
GroupAB has A and B antigens and no
antibodies in serum
They are significant for 2 reasons. they can
cause:
-Transfusion reaction
Group O receiving blood from group A or B
individuals
Fatal intravascular haemolysis leading to AHR
which result in DIC, renal failure, shock, death
- HDN
Group O mother carrying A or B child
Cases usually not so severe
Although regarded as RBC antigens, they are
actually expressed on a wide variety of human
tissues
Also
expressed on most epithelial and
endothelial cells and on my tissues including
heart, kidney, pancreas, lung etc
Eachhuman RBC expresses about 2 million ABO
blood group antigens
Otherblood cells, such as T cells, B cells, and
platelets, have ABO blood group antigens
In individuals who are "secretors", a soluble form
of ABO blood group antigens is found in saliva and
all body fluids except CSF.
Certainillnesses may alter ones ABO phenotype
eg. necrotising infection
haematological cancers
Others result in loss of ABO antigen eg. thalasemia
ABOgene is autosomal and located on
chromosome 9
A and B genes are dominant over the O gene
A and B are co-dominant ( express its
character when present in either
homozygote or heterozygote form
ABOalleles are passed on to offsprings by
parents
Genotype Phenotype
OO O
AA or AO A
BB or OB B
AB AB
Mother’s group O; Child’s group O
– Father 1?? – group A
– Father 2 ?? – group AB
Mother’s group A; child’s group A
– Father 1 ?? – group A
– Father 2 ?? – group B
A carbohydrate structure, H antigen is the
precursor for A and B antigens
Enzymes (glycosyltransferases) encoded by ABO
genes act on this to produce A and B antigens
α1,3-N-acetylgalactosaminyltransferaseattaches
N acetyl galactosamine to the H precursor make
A antigen
α1,3-galactosyltransferase
attaches D galactose
to the H precursor to make the B antigen
Twodifferent fucosyltansferases enzymes
code for the synthesis of the H antigen
FUT1 (H gene) and FUT2 (Se gene) encode
the H antigen expressed on RBCs and
secretions respectively
H antigen is the precursor for the synthesis of
both A and B antigens
Lack
of H antigen is known as Bombay
phenotype
Rare
In india (1 in 10,000), in Taiwan (1 in 8000), europe (1
per million
Individuals inherit the non functional form of the H
(hh) and secretor (sese)
H antigen is not expressed on RBCs.
H antigen is not found in saliva.
Serum contains anti-H.
Genotype: h/h se/se
Rare
H antigen is weakly expressed on RBCs.
H antigen may be present or absent in saliva.
Serum contains anti-H.
Genotype: (hh), Se/Se or Se/se
Group AB can receive red cells safely from any
of the ABO groups
Group O red cells can be given safely to any of
the ABO groups.
However, it is inadvisable to give O whole blood
as it may contain hyper immune anti A and Anti
B
Any other mismatch will cause a transfusion
reaction due to the presence of naturally
occurring antibodies
The four basic ABO phenotypes are O, A, B, and AB
Blood group A reacts differently to a particular
antibody (later Anti A1)
Blood group A further divided into A1 and A2
RBCs with the A1 phenotype react with anti-A1 and
make up about 80% of blood type A
A2 phenotype do not react with anti-A1
Both A1 and A2 types of red cell react with anti-A
A1 cells express about 5 times more A antigen
than A2 type red cells hence A2 cells react
more weakly than A1 with anti-A
A2 or A2B patients may sometimes be wrongly
classified as blood group O or B respectively
Other subgroups of blood group A exist which
tend to weakly express the A antigen
React more weakly with anti A
ABO antigens can be detected on red cells of
embryos As early as 5-6 weeks of gestation
However quantity on cord red cell is less than in
adults
Adult levels are generally expressed by age 2-4
years
Anti A and B are not present at birth
Antibody production start around 3-6 months
Nearly
all children express the appropriate
isohaemagglutinin by age 1
In adults ABO titre vary from 4-2048 or higher
Certain individuals have been found to have high
levels of anti A and B. eg. Multiparous group O
women and patients taking bacteria based
nutritional supplement-
Isoagglutinindecreases with increasing consumption
of processed food
Elderly????
No diseases are known to result from the lack of
expression of ABO blood group antigens
Susceptibility to a number of diseases has been
linked with a person's ABO phenotype
Still highly controversial
Eg include:
-Gastric cancer common in group A individuals
-Gastric and duodenal ulcers more often in O
-Group O ind have 25% less vWF and FVIII
therefore susceptible to excessive bleeding
-Non O ind increased risk of ischemic heart
disease and thromboembolic disease
In ABO grouping both cell grouping (forward
grouping and serum grouping ( reverse grouping)
are performed to avoid potential errors during
testing
In forward grouping, a known anti-serum
(commercially prepared anti A, anti B) is reacted
with unknown cells to test for the presence of
antigen A, B, O
In reverse grouping, known red cells containing
A,B,O antigens are reacted with unknown patient
serum to test for the presence of anti A and anti B
ABO grouping could be performed using:
1. Tile/ Slide method
2. Tube method
3. Microwell/ microtitre plate
technique
Newer methods
4. Gel columns method
5. Solid phase agglutination
Setup the tile as shown
Centrifuge and separate cells from serum
Wash cells three times in saline and make 20-25%
of the cells in saline
Puta drop of each anti serum in the appropriate
square for red cell grouping (forward grouping)
Puta drop of patient serum in appropriate square
and add a drop of 20-25% cell suspension of known
A (A1 or A2 )cells and B cells
Mixwith swab stick, rock tile forward and
backwards for 3 minutes. Read and record
results
Controlgroup ( drop of AB serum + drop of 20%
suspension of washed patient cells or drop of
patient serum) should be added to the test.
(what result is expected?????????)
Set up seven precipitin tubes and label them
Intotube 1 and 2 put two drops of anti sera A and
B respectively and add one drop of 5% cell
suspension of test cells.
Intotubes 3-5 put two drops of test sera and add
one drop of 5% suspension of known A (A1 or A2)
cells, B cells and O cells respectively
Set
up a control using 2 drops of AB serum and 1
drop of 5% suspension of washed cells
Mix and quick spin
Read(microscopically or macroscopically and
record results
Based on the principle of gel filtration
Gelconsist of a microtubes containing a dextran
gel matrix
The gel contains anti A, anti B
Red blood cells are dispensed into the tube
Withthe gel acting as a sieve, antigens
complementary to the antibody in the gel form an
agglutinate and are trapped in the gel
unagglutinatedred blood cells form a pellet at
the bottom of the microtube
The method depends on the
immobilisation of one of the
reactants so that during
testing the immobilised
component captures
additional reactants from the
liquid phase and binds them
to the solid phase
Positive
reaction appears as a button at the
bottom of the plate
Negative reaction appears as a diffuse
reaction
Reid ME, Bird GW. Associations between
human red cell blood group antigens and
disease. Transfus Med Rev 1990; 4:47-55.
O'Donnell J, Laffan MA. The relationship
between ABO histo-blood group, factor VIII and
von Willebrand factor. Transfus Med 2001;
11(4):343-51.
Fuchs CS, Mayer RJ. Gastric carcinoma. N Engl
J Med 1995; 333:32-41.
Reid ME and Lomas-Francis C. The Blood
Group Antigen Facts Book. Second ed. 2004,
New York: Elsevier Academic Press.
Daniels G. Human Blood Groups, Second ed.
2002, Blackwell Science
Stayboldt C, Rearden A, Lane TA. B antigen
acquired by normal A1 red cells exposed to a
patient's serum. Transfusion 1987; 27:41-4.
