ABO Basics• Blood group antigens are
actually sugars attached to the red blood cell.
• Antigens are “built” onto the red blood 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.
ABO Basics
• The immune system produces an antibody (protein) in the plasma (produced by white blood cells) for the antigen not present.
• Antibodies recognize foreigners and destroy them. Antibody B destroys antigen B.
• For example, blood type A has antigen A attached to the red blood cell and antibody B in their plasma. Therefore, if blood type B is injected into their systems, anti-B antibodies in their plasma will recognize it as an alien and destroy it.
Rh Factor
• Another important antigen (antigen D) found on the surface of blood cells is the Rh factor.
• Blood containing this antigen is said to be Rh positive (Rh+); blood lacking this antigen is said to be Rh negative (Rh-).
• Production of antibody to D requires exposure to the antigen.
• The D antigen is very immunogenic, ie, 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.
Rh Disease of the Neborn – How it Occurs• A) child is Rh + and mother is Rh -• B) during pregnancy fetal Rh + rbc’s escape into maternal circulation• C) This causes the mother's immune system to make antibodies against the baby's red
blood cells Rh (D) in future pregnancies. • D) Second pregnancy with Rh (D) pos child results in destruction of fetal D pos rbcs• This antibody response is called Rh sensitization and, depending on when it happens,
can destroy the red blood cells of the baby before or after it is born. • If sensitization happens, a fetus or newborn can develop mild to severe problems
(called Rh disease). In rare cases, if Rh disease is not treated, the fetus or newborn may die.
• A woman with Rh-negative blood can get a shot of Rh immunoglobulin (such as RhoGAM) that almost always stops sensitization from occurring. Problems from Rh sensitization have become very rare since Rh immunoglobulin was developed.
Hemolysis
• If an individual is transfused with an incompatible blood group destruction of the red blood cells will occur.
• This may result in the death of the recipient.
Clumping
• If a film remains uniform in appearance, there is no agglutination (clumping).
• If the sample appears granular, agglutination has occurred.
When does the blood react?
• Blood reacting to anti-A is group A. • Blood reacting to anti-B is group B.• Blood reacting to both anti-A and anti-B is
group AB.• Blood not reacting to either anti-A or anti-B is
group O. • Blood reacting to anti-Rh (D) is Rh+; Blood not
reacting to anti-Rh (D) is Rh-
How common is your blood type?
46.1%
38.8%
11.1%
3.9%
Blood Transfusion
Type You Can Give Blood To
You Can Receive Blood From
A A, AB A, OO ALL OB B, AB B, O AB AB ALL
TYPE YOU CAN GIVE BLOOD TO
YOU CAN RECEIVE BLOOD FROM
Rh + + + or -Rh - - -
With Rh-/Rh+
Type You Can Give Blood To
You Can Receive Blood From
A+ A+ AB+ A+ A- O+ O-O+ O+ A+ B+ AB+ O+ O-B+ B+ AB+ B+ B- O+ O-AB+ AB+ EveryoneA- A+ A- AB+ AB- A- O-O- Everyone O-B- B+ B- AB+ AB- B- O-AB- AB+ AB- AB- A- B- O-
