Download - ABO blood system
-
7/29/2019 ABO blood system
1/31
ABO BLOOD GROUP
DR. MOHAMMED H SAIEM ALDAHR
Faculty of Applied Medical Sciences
BLOOD BANK
MEDICAL TECNOLOGY
KAAU
-
7/29/2019 ABO blood system
2/31
ABO BLOOD GROUP
History1. Landsteiners discovered the ABO Blood Group
System in 1901
2. He and five co-workers began mixing each others redblood cells and serum together and accidentallyperformed the first forward and reverse ABOgroupings.
3. Landsteiners Rule: If an antigen (Ag) is present on apatients red blood cells the corresponding antibody (Ab) willNOTbe present in the patients plasma, under normalconditions.
-
7/29/2019 ABO blood system
3/31
ABO BLOOD GROUP
Importance of ABO
There are two principles
1-almost all normal healthy individuals above 3-6months of age have naturally occurring Abs to the
ABO Ags that they lack
These Abs termed naturally occurring because they
were thought to arise without antigenic stimulation
-
7/29/2019 ABO blood system
4/31
ABO BLOOD GROUP
Importance of ABO
2- These naturally occurring Abs are mostlyIgM class.That means that, they are Abs capable of agglutinatingsaline/ low protein suspended red cell withoutenhancement and may activate complement cascade.
-
7/29/2019 ABO blood system
5/31
Major ABO Blood Group
Forward blood grouping using anti-sera and red blood cells
ABO
Group
AntigenPresent
AntigenMissing
AntibodyPresent
A A B Anti-B
B B A Anti-A
O None A and B Anti-A&B
AB A and B None NoneIf an antigen (Ag) is present on a patients red blood cellsthe corresponding antibody (Ab) will NOT be present in thepatients plasma, under normal conditions.
-
7/29/2019 ABO blood system
6/31
ABO BLOOD GROUP (Forward blood grouping )Determination ofABO antigens found on patient red blood cells using reagent anti-sera. Serum from BG Baggl ARBCs, that an Ab to AAg was present in Grp B serum, serum fromAagg Grp B RBCs
Patient Red Cells Tested With
InterpretationAnti-BAnti-APatient
O001
A04+2
B4+03
AB4+4+4
-
7/29/2019 ABO blood system
7/31
Reverse Grouping (Confirmatory grouping)
Patient Serum Tested With reagent red blood cellsSerum from GRP O individual aggl bothAand B cells indicate the presence ofAbs to bothAand B in group O serum
InterpretationB CellsA1 CellsPatient
O4+4+1
A4+02
B04+3
AB004
-
7/29/2019 ABO blood system
8/31
FORWARD & REVERSE ABO BLOODGROUPING
Reaction of Cells TestedWith
Reaction of SerumTested Against ABO
Group
Anti-A Anti-B A1 Cells B Cells
1 0 0 + + O
2 + 0 0 + A
3 0 + + 0 B
4 + + 0 0 AB
-
7/29/2019 ABO blood system
9/31
-
7/29/2019 ABO blood system
10/31
ABO INHERITANCE
T2Dad =A/O
and
Mom = B/O
Mom
B O
DadA A/B A/O
O O/B O/O
-
7/29/2019 ABO blood system
11/31
ABO groups of the offspring from the various possible ABOmating
Phenotypes Genotype offspringAxA AAxAA A (AA)
AAxAO A (AA or AO)
AOxAO A (AA or AO),O(OO)
BxB BBxBO B (BB or BO)
AxAB AAxAB AB (AB) or A (AA)
AOxAB AB (AB), A (AA, AO), B(BO)
-
7/29/2019 ABO blood system
12/31
Inheritance
Definition
Isoagglutinins: are defined as antibodies that agglutinateblood cells of some individuals of the same species
Glycosyltransferases: are enzyme that facilitate thetransfer of carbohydrate (sugar) molecules ontocarbohydrate precursor molecules
Immunodominant sugar: is the sugar molecule thatcomplete the antigenic determinant when combined withthe precursor substance
-
7/29/2019 ABO blood system
13/31
ABH ANTIGEN
The inheritance of the ABO blood group was
demonstrated that each individual inherits one ABO gene
from each parent and these two genes determine which Agsare present on RBCs membrane
One position or Locus, on each chromosome number
nine is occupied by an A, B, or an O gene
-
7/29/2019 ABO blood system
14/31
ABH ANTIGEN
ALocus termed H and the final product of the genes atthat locus, H antigen, was necessary for the expression ofnormalABO antigens (Allele: any alternate form of a gene that can occupy a givenchromosomal location (locus).
ABHAgs of the RBC membrane are found partly asglycolipids,but primarily as glycoproteins. It may alsooccur in the secretion as glycoproteins.
-
7/29/2019 ABO blood system
15/31
ABH Antigens
Ags belonging toABH blood group system are present onRBCs and other body cells and body fluids.
The presence of A,B, and O Ags on RBCs depends uponthe allelic genes, A,B, and O
An Hgenes at a separate locus codes for the precursorsubstance on which theAand B gene products act
The products of theA and B genes are enzymes that act asa specific transferases
-
7/29/2019 ABO blood system
16/31
ABH Antigens
H gene products is an enzyme that produce H substance
The O gene is a silent allele
It does not alter the structure ofH substance.
-
7/29/2019 ABO blood system
17/31
Formation of A1B& H Antigen
TheABO genesdo not code for the production ofABOantigens, BUT rather produce specific glycosyltransferases
ABO produces a specific glycosyl transferases that add
sugars to a basic precursor substance on the RBCs
A donor nucleotide derivative supplies the sugar thatconfers (gives) ABO specificity (is the sugar molecule thatcomplete the antigenic determinant when combined with
the precursor substance )
The formation ofABH antigens results from theinteraction of ABO genes with several other separate,
independent blood groups.
-
7/29/2019 ABO blood system
18/31
Formation of A1B& H Antigen
The inheritance of at least one H gene (HH or Hh) elicits(obtain) the production of an enzyme called, -2-L-Fucosyl transferase, which transfers the sugar from the
Guanosine diphosphate L-fucose (GDP-Fuc) donornucleotide to the terminal galactose of the precursorchain.
The H substance must be formed for the other sugars to
be attached in response to an inherited A and /or B genes
-
7/29/2019 ABO blood system
19/31
ABH Ag
There are two potential precursors substance (PS) both arecomprised of identical sugar (galactos-N- acetylgluctosamin - galactose -glucose) but different in linkage.
Type I PS has a terminal galactose (Gal) linked to asubterminal N acetylgucoseamine (GlcNAc) in 1-3linkage
Type II PS, has the same sugar combine in 1-4 linkage
ABH Ags on RBCs are derived from Type II chains.
-
7/29/2019 ABO blood system
20/31
ABO Genetics
Genes at three separate loci control the occurrence andlocation of A and B antigens
1. Hh genes Hand h alleles
Hallele codes for a fucosyltransferase enzyme thatadds a fucose on Type 2 chains (primarily) to form theH antigen onto which A and B antigens are built onred blood cells.
h allele is a silent allele (amorph)
-
7/29/2019 ABO blood system
21/31
ABO Genetics
A, B and H antigens are built
on oligosaccharide chains of 4types. The most commonforms are Type 1 and Type 2.
Type 1: #1 carbon of Gal is
attached to the #3 carbon ofGlcNAc.
Type 2: #1 carbon of Gal isattached to the #4 carbon of
GlcNAc.
-
7/29/2019 ABO blood system
22/31
ABO Genetics
2- Se genes
Se and se allelesSe allele codes for a fucosyltransferase enzyme that
adds fuscos onto Type 1 chains (primarily) insecretory glands. Controls expression of H antigens in
secretions (i.e. saliva, body fluids, etc.) se allele is an a morph
3. ABO genes A,B and O alleles
A and Balleles code for (glycosyltransferase)afucosyltransferase enzymes that add a sugar onto Hantigens to produce A and B antigens
O allele does not code a functional enzyme
-
7/29/2019 ABO blood system
23/31
ABO Genetics
1. Occurance
a. The presence or absence of theABH antigens onthe red blood cell membrane is controlled by theHgene
b. Presence or absence of theABH antigens insecretions is indirectly controlled by theSe genes.
-
7/29/2019 ABO blood system
24/31
ABO Genetics
1. Hh gene Hand halleles (h is an a morph)
2. Se gene Se and sealleles (se is an amorph)
3. ABO genes A, B and Oalleles
1. Controls presence of H,A, and B antigens onboth RBCs and in
Secretions
2. Controls presence of Hantigen in the secretions
3. Inherit 1 gene from eachparent that codes for anenzyme that adds asugar to the H antigen
-
7/29/2019 ABO blood system
25/31
H gene acts on
a Precursor
substance(PS)*
by addingFucose
H Antigen
*PS = oligosaccharide chain
attached to either glycosphingo-
lipid, Type 2 chain (on RBC) or
glycoprotein, Type 1 chain (in
secretions)
TheHgene codes for an enzyme (fucosylytranferase) that adds a
Fucose to the terminal sugar of a Precursor Substance (PS*).The biochemical structure below constitutes the H Antigen. (hgene is an amorph.)
-
7/29/2019 ABO blood system
26/31
ABO Genetics
H antigen is the foundation upon which A and Bantigens are built.A andB genes code for
enzymes that add an immunodominant sugar tothe H antigen.
-
7/29/2019 ABO blood system
27/31
Formation of theA Antigen
TheA gene codes
for an enzyme that
adds GalNAc(N-Acetyl-D
galactosamine)
to the terminal
sugar of theH Antigen. The biochemical structure
constitutes the A antigen.
-
7/29/2019 ABO blood system
28/31
Formation of theB Antigen
Bgene codes for an
enzyme that adds
D-Galactoseto the terminal sugar
of the H Antigen.
The biochemical structure
constitutes theB Antigen.
-
7/29/2019 ABO blood system
29/31
The H antigen is found on
the RBCs when there is anHh
orHHgenotypes but NOT
with the hh genotype.
The A antigen is found on
the RBCs when there isHh,
HH, andA/A,A/O or A/B
genotypes.
The B antigen is found on
the RBCs when there isHh,
HH, andB/B,B/O or A/B
genotypes.
-
7/29/2019 ABO blood system
30/31
Amount of H Antigen According to Blood Group
Blood Group O peoplehave red blood cellsrich in H antigen.
Why?
Neither the A or B genes have converted the Hantigens to A or B antigens - just a whole bunch ofH!
O allele at the ABO locus (amorph)It does not alter the structure of Hsubstance.
GreatestAmount of H
LeastAmount of H
O > A2 > B > A2B > A1 > A1B
-
7/29/2019 ABO blood system
31/31
Donor Nucleotides & Immundominant Sugars responsible
for H, A, and B Ags specificity
AntigenImmunodominant sugarNucleotideGlcosyltransferaseGene
HL-fucoseGuanosine
GDP-FUC
L- fucosyl trnsferasH
AN-acetyl-D-galactoseamine
Uridine
UDP-GALNAC
N acetylgalactosaminyl
transferaseA
BD-galactoseUridine
UDP-GALD- galactosyltransferase
B