Download - ABO and Rh Typing
ABO and Rh Typing
Composition of Blood
ANTIGEN – substances that induces an immune response by causing production of antibodies
ANTIBODY - serum protein that is induced by, and reacts specifically with a foreign substance (Ag)
ABO Blood Group System• Discovered by Karl Landsteiner; on chromosome 9
• Single most important blood group for the selection and transfusion of blood
• Three antigens: A, B, H
• Two major antibodies: anti-A and anti-B
• Four phenotypes: A, B, AB, O
ABO AntigensPresent on the surface of red cells as well as
tissue and endothelial cells in the body
Found in soluble form in the plasma and other body secretions in people known as secretors
3 possible genes tat an be inherited: A, B, and O
ABO AntibodiesNatural antibodies antigenic stimulus is
environment exposure occur at birth
Newborns without ABO antibodies of their own; begin to produce wit detectable titers at 6 months age
According to the ABO blood typing system there are four different kinds of blood types: A, B, AB or O (null).
ABO blood grouping system
Blood group AIf you belong to the blood group A, you have A antigens on the surface of your RBCs and B antibodies in your blood plasma.
Blood group BIf you belong to the blood group B, you have B antigens on the surface of your RBCs and A antibodies in your blood plasma.
AB0 blood grouping system
Blood Group
Antigens on RBCs
Antibodies in Serum
Genotypes
A A Anti-B AA or AO
B B Anti-A BB or BO
AB A and B Neither AB
O Neither Anti-A and anti-B OO
ABO Routine TestingIndirect/Reverse Typing
Known antigen (cell) vs unknown antibody (patient’s serum)
Serum is combined with cells having known antigen content in ratio 2:1 ratio
Uses commercially prepared reagents containing saline suspended A1 and B cells
Reaction Patterns for ABOBlood Group Agglutination w/ Anti-
AAgglutination w/ Anti-
B
A + -
B - +
AB + +
O _ _
ABO Routine TestingIndirect/Reverse Typing
Known antigen (cell) vs unknown antibody (patient’s serum)
Serum is combined with cells having known antigen content in ratio 2:1 ratio
Uses commercially prepared reagents containing saline suspended A1 and B cells
Reaction Patterns for ABOBlood Group Agglutination w/ A
cellsAgglutination w/ B
cells
A _ +
B + _
AB _ _
O + +
Slide Blood TypingThe slide is divided into halves.On one side a drop of anti-A is added, this will
attach to and cause clumping of rbcs possessing the A antigen.
On the other side a drop of anti-B is added which will cause clumping of rbcs with the B antigen.
A drop of rbcs is added to each side and mixed well with the reagent.
The slide is tilted back and forth for one minute and observed for agglutination (clumping) of the rbcs
Interpretation of Slide TypingTesting with Anti-A Anti-Serum
If an rbc contains the A antigen the red blood cells will be agglutinated by anti-A, a positive reaction.
If an rbc does not have the A antigen there will be no clumping, a negative reaction.
Interpretation of Slide TypingTesting with Anti-B Anti-SerumIf an rbc contains the B
antigen the red blood cells will be agglutinated by anti-B, a positive reaction.
If an rbc does not have the B antigen there will be no clumping by anti-B, a negative reaction.
Slide Blood Typing Group AAn unknown rbc suspension is added to known
anti-sera.The left hand of the slide contains anti-A which
reacts with the unknown cell.The right hand side contains anti-B which does
not react with the cell.
Slide Blood Typing Group BAn unknown rbc suspension is added to known
anti-sera.The left hand of the slide contains anti-A does
not react with the unknown cell.The right hand side contains anti-B which reacts
with the cell.
Slide Blood Typing Group OThe left hand of the slide contains anti-A
does not react with the unknown cell.The right hand side contains anti-B does
not react with the unknown cell.
Slide Blood Typing Group ABThe left hand of the slide contains anti-A
which reacts with the unknown cell.The right hand side contains anti-B
which reacts with the unknown cell.
Summary of Slide TypingAnti-A Anti-B Blood Group
NEG NEG O
POS NEG A
NEG POS B
POS POS AB
Example of Determining GenotypeMom’s phenotype is group A, genotype
AODad’s phenotype is group B, genotype
BO B O
A AB 25% AO 25% (Group A)
O BO 25% (Group B) OO 25% (Group O)
Rh Blood GroupAnother common way to group blood types is
using Rh antigensRh stands for ‘Rhesus’ because the Rh antigen
was first found in the Rhesus monkeyPeople with the Rh antigen are ‘Rh positive
(Rh+)’, whereas those without the antigen are ‘Rh negative (Rh -)’
Blood plasma does not normally contain anti-Rh antibodies
Hemolytic Disease of the Newborn: Rh Disease
If the fetus has Rh+ blood and the mother has Rh- blood, then the mother will make anti-Rh antibodies
However, contact between fetal and maternal blood is greatest during childbirth, and thus the firstborn baby is usually not affected
• The most common problem with Rh incompatibility is during pregnancy
• A small amount of blood from the fetus may contact the blood of the mother through the placenta
Treatment of HDN• If a woman has Rh- and gives birth to a child,
or if she has a miscarriage or abortion, she is given an injection of anti-Rh antibodies called anti-Rh gamma globulin or RhoGAM to prevent HDN.
• The antibodies bind to the fetal Rh antigens and inactivates them if they crossed the placenta during birth, and the mother’s immune system does not respond by producing antibodies.