ABO Blood system Muhammad Asif zeb Lecturer –Hematology Khyba medical university Peshawar
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ABO Blood systemMuhammad Asif zebLecturer –HematologyKhyba medical university Peshawar
Blood Grouping
History - Karl Landsteiner
Discovered the ABO Blood Group System in 1901
He and his five co-workers began mixing each others red cells and serum together and inadvertently performed the first forward and reverse ABO groupings
Landsteiners Rule
Karl Landsteiner’s law : If an antigen is present in the RBC’s of an individual, the corresponding antibody must be absent from the plasma
If an antigen is absent in the RBC’s of an individual, the corresponding antibody must be present from the plasma
’.
Major ABO Blood Group
ABO Group
Antigen Present
Antigen Missing
Antibody Present
A A B Anti-BB B A Anti-AO None A and B Anti-A&B
AB A and B None None
ABO Basics
Blood group antigens are actually sugars attached to the red blood cell.
Antigens are “built” onto the red cell.
Individuals inherit a gene which codes for specific sugar(s) to be added to the red cell.
The type of sugar added determines the blood group
Principle of blood grouping
There are two principles 1-almost all normal healthy individuals above 3-6 months 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
Principle of blood grouping
2- These “naturally occurring” Abs are mostly IgM class. That means that, they are Abs capable of agglutinating saline/ low protein suspended red cell without enhancement and may activate complement cascade.
ABO and H Antigen GeneticsABO chromo 9O gene on chrom 19
Ags belonging to ABH blood group system are present on RBCs and other body cells and body fluids.
The presence of A,B, and O Ags on RBCs depends upon the allelic genes, A,B, and O
An H genes at a separate locus codes for the precursor substance on which the A and B gene products act
The products of the A and B genes are enzymes that act as a specific transferases
Genetics
The ABO genes do not code for the production of ABO antigens, BUT rather produce specific glycosyl transferases
ABO produces a specific glycosyl transferases that add sugars to a basic precursor substance on the RBCs
RBC Precursor Structure Glucose
Galactose
N-acetylglucosamine
Galactose
Precursor Substance (stays the
same)
RBC
There are two potential precursors substance (PS) both are comprised of identical sugar (galactos-N- acetyl gluctosamin - galactose -glucose) but different in linkage.
Type I PS has a terminal galactose (Gal) linked to a subterminal N acetylgucoseamine (GlcNAc) in 1-3 linkage
Type II PS, has the same sugar combine in 1-4 linkage
ABH Ags on RBCs are derived from Type II chains
H Antigen
The inheritance of at least one H gene (HH or Hh) elicits (obtain) the production of an enzyme called, α-2-L-Fucosyl transferase, which transfers the sugar from the Guanosine diphosphate L-fucose (GDP-Fuc) donor nucleotide to the terminal galactose of the precursor chain.
The H substance must be formed for the other sugars to be attached in response to an inherited A and /or B genes
Formation of the H antigen Glucose
Galactose
N-acetylglucosamine
Galactose
Precursor Substance (stays the
same)
RBC
H antigen
Fucose
A and B Antigen
The “A” gene codes for an enzyme (transferase) that adds N-acetylgalactosamine to the terminal sugar of the H antigen N-acetylgalactosaminyltransferase
The “B” gene codes for an enzyme that adds D-galactose to the terminal sugar of the H antigen D-galactosyltransferase
Formation of the A antigen Glucose
Galactose
N-acetylglucosamine
Galactose
RBC
FucoseN-acetylgalactosamine
A antigen
Formation of the B antigen Glucose
Galactose
N-acetylglucosamine
Galactose
RBC
FucoseGalactose B antigen
Formation of the AB antigen
Glucose
Galactose
N-acetylglucosamine
Galactose
RBC
Fucose
Galactose B antigen
N-acetylgalactosamine A antigen
Formation of the H antigen Glucose
Galactose
N-acetylglucosamine
Galactose
Precursor Substance (stays the
same)
RBC
H antigen
Fucose O antigen
H antigen
Certain blood types possess more H antigen than others:
O>A2>B>A2B>A1>A1B
Genetics
The H antigen is found on the RBC when you have the Hh or HH genotype, but NOT from the hh genotype
The A antigen is found on the RBC when you have the Hh, HH, and A/A, A/O, or A/B genotypes
The B antigen is found on the RBC when you have the Hh, HH, and B/B, B/O, or A/B genotypes
Bombay Phenotype (Oh)
Inheritance of hh
The h gene is an amorph and results in little or no production of L-fucosyltransferase
Originally found in Bombay
Very rare (130 worldwide)
Bombay Phenotype (Oh)
The hh causes NO H antigen to be produced Results in RBCs with no H, A, or B antigen (patient types as O)
Bombay RBCs are NOT agglutinated with anti-A, anti-B, or anti-H (no antigens present)
Bombay serum has strong anti-A, anti-B and anti-H, agglutinating ALL ABO blood groups
What blood ABO blood group would you use to transfuse this patient??
Another BombayGroup O RBCs cannot be given because
they still have the H antigenYou have to transfuse the patient with
blood that contains NO H antigen
ABO antibodies
Group A serum contains anti-B Group B serum contains anti-A Group AB serum contains no antibodies Group O serum contains anti-A, anti-B, and anti-A,B
ABO antibodies
IgM is the predominant antibody in Group A and Group B individuals Anti-A Anti-B
IgG (with some IgM) is the predominant antibody in Group O individuals Anti-A,B (with some anti-A and anti-B)
ABO antibodies
Reactions phase: Room temperature Complement can be activated with ABO antibodies (mostly IgM, some IgG)
High titer: react strongly (4+) Usually present within the first 3-6 months of life
Stable by ages 5-6 years Decline in older age Newborns may passively acquire maternal antibodies (IgG crosses placenta) Reverse grouping (with serum) should not be
performed on newborns or cord blood
ABO routine testing
Several methods for testing the ABO group of an individual exist. The most common method is:
Serology: This is a direct detection of the ABO antigens. It is the main method used in blood transfusion centres and hospital blood banks.
This form of testing involves two components: a) Antibodies that are specific at detecting a particular ABO antigen on RBCs.
b) Cells that are of a known ABO group that are agglutinated by the naturally occurring antibodies in the person's serum.
ABO ROUTINE TESTING
DIRECT OR FORWARD GROUPINGTest for antigens• Patient’s cells containing unknown antigens tested with known antisera
• Antisera manufactured from human seraAantisera used:Antisera Color SourceAnti-A Blue Group B donorAnti-B Yellow Group A donorAnti-A,B Red Group O donor
Forward Grouping
Reaction of patient red blood cells tested with Reagent anti-A and anti-B antisera
Slide: 20-40% RBC suspension + anti-serum
Tube (12x75mm): 2-5% RBC suspension + anti-serum (centrifuge before read)
Forward Grouping
Reaction Patterns for ABO Groups
Blood group Agglutination with Anti-A
Agglutination with Anti-B
A + -
B - +
AB + +
O - -
Reverse grouping
• serum is combined with cells having known Ag content in a 2:1 ratio
• uses commercially prepared reagents containing saline-suspended A1 and B cells
Reverse grouping
Reaction Patterns for ABO Groups
Blood Group Agglutination with A cells
Agglutination with B cells
A - +
B + -
AB - -
O + +
Grading of Agglutination:
Negative (0) No clumps or aggregatesWeak (+/-) Tiny clumps or aggregates barely
visible macroscopically or to the naked eye
1+ Few small aggregates visible macroscopically
2+ Medium-sized aggregates3+ Several large aggregates4+ One solid aggregate
ABO blood group (forward blood grouping)
Patient Red Cells Tested With
Interpretation Anti-B Anti-A Patient
0 0 10 4+ 2
4+ 0 34+ 4+ 4
ABO blood group (forward blood grouping)
Patient Red Cells Tested With
Interpretation Anti-B Anti-A Patient
O 0 0 1A 0 4+ 2B 4+ 0 3
AB 4+ 4+ 4
Reverse Grouping (Confirmatory grouping
Patient SERUM Tested With
Interpretation
B Cells A1 Cells Patient
4+ 4+ 14+ 0 20 4+ 30 0 4
Reverse Grouping (Confirmatory grouping
Patient SERUMTested With
Interpretation
B Cells A1 Cells Patient
O 4+ 4+ 1A 4+ 0 2B 0 4+ 3
AB 0 0 4
Forward & reverse ABO blood grouping
Reaction of Cells Tested With
Reaction of Serum Tested Against ABO
GroupAnti-A Anti-B A1 Cells B Cells
1 0 0 + + O
2 + 0 0 + A
3 0 + + 0 B
4 + + 0 0 AB
Forward & reverse ABO blood grouping
Reaction of Cells Tested With
Reaction of Serum Tested Against ABO
GroupAnti-A Anti-B A1 Cells B Cells
1 0 0 + +2 + 0 0 +3 0 + + 04 + + 0 0
ID card system
This ID-Card contains a mixture of human polyclonal and monoclonal anti-A, human polyclonal anti-B and human polyclonal anti-D antibodies.
The microtube ctl is the negative control. Two microtubes with neutral gel serve for reverse grouping with A1 and B cells.
Thank you….
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