1. BLOOD GROUP SYSTEM

2. Introduction
 A blood group also called a Blood Type
 Classification of blood is based on the
presence or absence of inherited
antigenic substances on the surface of red
blood cells (RBCs).
 Blood group systems
◦ ABO blood group system
◦ Rh blood group system

3. Introduction
 Karl Landsteiner discovered the ABO Blood
Group System in 1901.
 The ABO blood group system is the most
important blood group system in human blood
transfusion.
 Determination of ABO blood groups depends
upon the immunological reaction between
antigen and antibody.

4. Landsteiner Rule:
 If an antigen is present on a patients red
blood cells (RBCs) the corresponding
antibody will NOT be present in the
patients plasma, under ‘normal
conditions’.

5. Based on the presence or absence of
antigen A and antigen B, blood is divided
into four groups:
1. A
2. B
3. AB
4. O

6. Cont..
 Blood having antigen A belongs to ‘A’
group. This blood has β-antibody in the
serum.
 Blood with antigen B and α-antibody
belongs to ‘B’ group.
 If both the antigens are present, blood
group is called ‘AB’ group and serum of
this group does not contain any antibody.
 If both antigens are absent, the blood
group is called ‘O’ group and both α and β
antibodies are present in the serum.

8.  It is the most important blood group
system after ABO.
 The Rh blood group system was
discovered in 1940 by Karl
Landsteiner and A.S.Weiner.
 It was first discovered in Rhesus monkey
and hence the name 'Rh factor’

9. Cont..
 The Rh blood group system consists of 49
defined blood group antigens among
which the five antigens D, C, c, E, and e are
the most important.
 The type D antigen is widely prevalent in
the population.
 Anyone who has this type of antigen is
said to be Rh positive, whereas a person
who does not have type D antigen is said
to be Rh negative.

10. Rh Incompatibility
Erythroblastosis fetalis
 Mother Rh negative and fetus Rh positive
 RBCs from the fetus can go into mothers
bloodstream through the placenta
 Rh negative mothers immune system treats
the Rh positive fetal cells as a foreign
substance and makes antibodies against them
 Theses anti Rh antibodies may cross the
placenta into the fetus where they destroy
the fetus’s circulation RBCs.

13. Blood Groups Compatibility