The ABO blood group system is one of the most important blood group systems for transfusions. It is determined by the ABO gene which has three alleles - IA, IB, and i - that encode for the A, B, and O antigens, respectively. The ABO blood types are determined by which alleles are present: IAIA or IAi produce type A blood, IBIB or IBi produce type B, IAIB produces AB, and ii produces O. The Rh system, specifically the D antigen, is the second most important blood group and sensitization to the D antigen in Rh-negative pregnant women can cause hemolytic disease of the newborn if not prevented.
2. ABO BLOOD GROUP SYSTEM
❑The ABO blood group system is the most
important blood group system in human blood
transfusion.
❑ Found on platelets, epithelium and cells other
than erythrocytes, AB antigens can also cause an
adverse immune response to organ transplantation. The
associated anti-A and anti-B antibodies are
usually IgM antibodies, which are produced in the first
years of life by sensitization to environmental
substances, such as food, bacteria, and viruses.
4. ● HISTORY
➢ KARL LANDSTEINER discovered the ABO
Blood Group System in 1901.
➢He and five co-workers began
mixing each others red blood cells
and serum together and
accidentally performed the
first forward and reverse ABO groupings.
5. LANDSTEINER’S LAW
a) If an agglutinogen is present on red blood
cell membrane, the corresponding
agglutinin must be absent in the plasma.
b) If an agglutinogen is absent on red blood
cell membrane, then the corresponding
agglutinin must be present in the plasma.
6. IMPORTA NCE OF A BO
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.
7. 2) These “naturally occurring” Abs are mostly IgM
class. That means that, they are antibodies capable
of agglutinating saline/ low protein suspended red
cell without enhancement and may activate
complement cascade.
* *
8. BLOOD GROUP ANTIGENS
ON CELL
ANTIBODIES
IN PLASMA
A A Anti-B
B B Anti-A
AB A and B none
O None Anti-A and B
9. ABO TYPING
❖ ABO typing involves both antigen typing and antibody
detection. The antigen typing is referred to
as the forward typing and the antibody
detection is the reverse typing
●The forward typing determines antigens on
patient's or donor's cells
a.Cells are tested with the antisera reagents anti- A,
anti-B, (and in the case of donor cells anti-A,B)
b.Reagents are either made from hyper
immunized human sources, or monoclonal
antibodies.
c.One advantages of the monoclonal antibodies are
the antibody strength.
11. ● The reverse typing determines antibodies in
patient’s or donor’s cells.
a. Serum tested with reagent A1 cells and B cells
b.Reverse grouping is also known as backtyping
or serum confirmation
REVERSE TYPING
REACTIONS OF SERUM TESTED
AGAINST
REVERSE ABO GROUP
O
A
B
A1 Cells B Cells
+ +
0 +
+ 0
0 0 AB
12.
13. ABO GENE &
GENETICS
❑ The ABO blood type is controlled by a single gene (the ABO
gene) with three types of alleles i, IA, and IB.
❑ The Idesignation stands for isoagglutinogen , another
term for antigen.
❑
❑
❑
❑
The gene encodes a glycosyltransferase .
The gene is located on the long arm of the ninth
chromosome (9q34)
IAallele gives type A, IB gives type B, i gives type O.
IAand IB are dominant over i.
❑ O group : Only ii
❑ A group : IAIA or IAi
AB group : IAIB
B group : IBIBor IB i
❑ IA
IB people have both phenotypes, becauseA and B express a
special dominance relationship: co dominance, which means that
typeA and B parents can have an AB child.
14. A and B
are co
dominan
t giving
the AB
phenotyp
.e
16. ABO ANITGEN GENETICS
●The presence or absence of the ABH
antigens on the red blood cell
membrane is controlled by the H gene
●• The presence or absence of the
ABH antigens in secretions is
indirectly controlled by the Se gene
●• H gene – H and h alleles (h is an
amorph)
●• Se gene – Se and se alleles (se is
an amorph)
17. BOMBAY GROUP
●The h/h blood group, also known as Oh[ or
the Bombay blood group, is a rare blood
type. This blood [phenotype] was first
discovered in Bombay, now known
as Mumbai, in India, by Dr. Y.M.Bhende in
1952.
●The Hh blood group contains one antigen,
the H antigen, which is found on virtually all
RBCs and is the building block for the
production of the antigens within the ABO
blood group.
18. H antigen deficiency is known as the
"Bombay phenotype" (h/h, also known as
Oh) and is found in 1 of 10,000 individuals
in India and 1 in a million people in Europe.
There is no ill effect with being H deficient,
but if a blood transfusion is ever needed,
people with this blood type can receive
blood only from other donors who are also
H deficient. (A transfusion of "normal" group
O blood can trigger a severe transfusion
reaction.)
●The peculiarity is that they do not express
the H antigen. As a result they cannot form
A antigens or B antigens on their red blood
cells. Thus they can donate blood to
anyone.
19. RH BLOOD GROUP SYSTEM
oThe Rh blood group system (including
the Rh factor) is one of thirty-five
current human blood group systems. It is
the second most important blood group
system, after ABO.
o Rh derives from rhesus and the terms
rŁesus blood group system, rŁesus
factor, rŁesus positive and rŁesus
ne gative are also used.
o Rh is a blood group system with many
antigens, one of which is D.
20. RH (D) ANTIGEN
●Unlike the ABO blood group system,
individuals who lack the D antigen do
not naturally make it.
●Production of antibody to D requires
exposure to the antigen.
●The D antigen is very immunogenic,
i.e, individuals exposed to it will very
likely make an antibody to it.
●For this reason all individuals are
typed for D, if negative must receive
Rh (D) negative blood.
21. RH (D) ANTIGEN
{CONTINUED}
●The most important patient population
to consider is females of child-bearing
age.
●If immunized to Rh (D) antigen the
antibody can cross the placenta and
destroy Rh (D) positive fetal cells
resulting in death.
●This is why Rh negative women are
given Rhogam after birth of Rh
positive baby.
