Blood Type Flashcards
Type A Blood
A Antigens present on RBC, anti-B antibodies in blood
Type B Blood
B Antigens present on RBC, anti-A antibodies in blood
Type AB Blood
Universal acceptor: no antibodies in blood, both A and B type antigens on RBCs
Type O Blood
Universal donor: both anti-A and anti-B antibodies in Blood, but no antigens on surface of RBCs
What are blood type antigens?
Chains of sugars on the surface of RBCs: the only difference between A and B is that B terminates in a galactose while A terminates in a galactosamine.
Type O antigen is the same length as A and B except that it is missing that final terminal sugar.
How do we get our blood type?
From the enzymes encoded for in our genome. A ‘Type A’ enzyme add the terminal galactosamine to our RBCs, making us Type A. If we get both A and B enzymes, one from Mom and one from Dad, then we get both kinds of sugars on cell surfaces.
Rhesus Factor
D protein on the surface of RBCs
There is A+, A-, B+, B-
+ indicates that there is rhesus antigen
When is rhesus factor clinically important?
In case where mother is rhesus negative and father is rhesus positive and she has her SECOND rhesus positive baby.
First pregnancy with rhesus positive baby leads to production of anti-rhesus antibodies. This is primary exposure.
So during second pregnancy, will unleash immune response when those antibodies cross placenta barrier to attack the non-self fetus.
RhoGAM is a treatment: destroys rhesus+ cells that enter mother’s blood during pregnancy, so cannot generate primary immune response.
What happens during incompatible blood transfusion?
Antibodies in your blood attack cells of non-self RBCs and clump them up (opsonization), preventing them from acting. This triggers complement cascade and hemolysis.
What’s the point of having different blood types?
May confer immunity or resistance to certain diseases that were more prevalent in certain genetic populations in the past.
