The document summarizes the ABO blood group system, which was discovered in 1901 by Karl Landsteiner. It describes the antigens and antibodies present in the four main blood groups (A, B, AB, and O) based on the presence or absence of the A and B antigens. The genes that code for the A, B, and H antigens are explained, as well as how they produce specific enzymes that add sugars to precursor structures on red blood cells. Forward and reverse blood grouping tests are outlined to determine a person's blood group.

1. ABO Blood system
Muhammad Asif zeb
Lecturer –Hematology
Khyba medical university
Peshawar

2. BloodGrouping

3. 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

4. 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
’.

5. MajorABO
BloodGroup
ABO
Group
Antigen
Present
Antigen
Missing
Antibody
Present
A A B Anti-B
B B A Anti-A
O None A and B Anti-A&B
AB A and B None None

6. 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

7. 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

8. 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.

9. ABO and H
Antigen
Genetics
ABO chromo
9
O 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

10. 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

11. RBC Precursor
Structure Glucose
Galactose
N-acetylglucosamine
Galactose
Precursor
Substance
(stays the
same)
RBC

12. 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

13. HAntigen
 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

14. Formation of
the H antigen Glucose
Galactose
N-acetylglucosamine
Galactose
Precursor
Substance
(stays the
same)
RBC
H antigen
Fucose

15. 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

16. Formation of
theA antigen Glucose
Galactose
N-acetylglucosamine
Galactose
RBC
Fucose
N-acetylgalactosamine
A antigen

17. Formation of
the B antigen Glucose
Galactose
N-acetylglucosamine
Galactose
RBC
Fucose
Galactose B antigen

18. Formation of
theAB
antigen
Glucose
Galactose
N-acetylglucosamine
Galactose
RBC
Fucose
Galactose B antigen
N-acetylgalactosamine A antigen

19. Formation of
the H antigen Glucose
Galactose
N-acetylglucosamine
Galactose
Precursor
Substance
(stays the
same)
RBC
H antigen
Fucose
O antigen

20. H antigen
 Certain blood types possess more H antigen than
others:
O>A2>B>A2B>A1>A1B

21. 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, orA/B genotypes

22. 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)

23. 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 bloodABO blood group would you use to
transfuse this patient??
Another Bombay
Group O RBCs cannot be given because they still
have the H antigen
You have to transfuse the patient with blood that
contains NO H antigen

24. ABO
antibodies
 GroupA serum contains anti-B
 Group B serum contains anti-A
 GroupAB serum contains no antibodies
 GroupO serum contains anti-A, anti-B, and anti-A,B

25. ABO
antibodies
 IgM is the predominant antibody in GroupA and Group
B individuals
 Anti-A
 Anti-B
 IgG (with some IgM) is the predominant antibody in
GroupO individuals
 Anti-A,B (with some anti-A and anti-B)

26. 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

27. 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.

28. ABO
ROUTINE
TESTING
DIRECT OR FORWARD GROUPING
Test for antigens
• Patient’s cells containing unknown antigens tested
with known antisera
• Antisera manufactured from human sera
Aantisera used:
Antisera Color Source
Anti-A Blue Group B donor
Anti-B Yellow Group A donor
Anti-A,B Red Group O donor

29. 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)

30. Forward
Grouping
Reaction Patterns for ABO Groups
Blood group Agglutination with
Anti-A
Agglutination with
Anti-B
A + -
B - +
AB + +
O - -

31. 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

32. Reverse
grouping
Reaction Patterns for ABO Groups
Blood Group Agglutination with
A cells
Agglutination with
B cells
A - +
B + -
AB - -
O + +

33.  Grading of Agglutination:
Negative (0) No clumps or aggregates
Weak (+/-) Tiny clumps or aggregates barely
visible macroscopically or to the
naked eye
1+ Few small aggregates visible
macroscopically
2+ Medium-sized aggregates
3+ Several large aggregates
4+ One solid aggregate

34. ABO blood
group
(forward blood
grouping)
Patient Red CellsTested With
Interpretation
Anti-B
Anti-A
Patient
0
0
1
0
4+
2
4+
0
3
4+
4+
4

35. ABO blood
group
(forward blood
grouping)
Patient Red CellsTested With
Interpretation
Anti-B
Anti-A
Patient
O
0
0
1
A
0
4+
2
B
4+
0
3
AB
4+
4+
4

36. Reverse
Grouping
(Confirmatory
grouping
Patient SERUMTestedWith
Interpretation
B Cells
A1 Cells
Patient
4+
4+
1
4+
0
2
0
4+
3
0
0
4

37. Reverse
Grouping
(Confirmatory
grouping
Patient SERUMTestedWith
Interpretation
B Cells
A1 Cells
Patient
O
4+
4+
1
A
4+
0
2
B
0
4+
3
AB
0
0
4

38. Forward &
reverse
ABO blood
grouping
Reaction of CellsTested With
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

39. Forward &
reverse
ABO blood
grouping
Reaction of CellsTested With
Reaction of SerumTested
Against ABO
Group
Anti-A Anti-B A1 Cells B Cells
1 0 0 + +
2 + 0 0 +
3 0 + + 0
4 + + 0 0

40. 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.

41. Thank you….