Why O antigen (ABO blood group) does not activate immune system? - (Nov/01/2009 )
The ABO blood group is used to discribe the defferent of glycoprotein on RBC surface. In the other word, there are 3 type of antigen on RBC but why there are only A abd B antigens the can stimulate the immune system? Why O does not? I really can't find the answer. Anyway, thank for reading my question.
Because O means there are no A or B antigens on the membrane, its not a different class of antigen
On the surface is the H antigen to which either A (N acetyl glucosamine) or B ( a D glactose) are attached to the end.
A or B blood introduced to a O person will stimulate a response. AB has both (universal recipient; will not produce abs to either a, b, or o. O is universal donor and will produce abs to a or b.
Gerard on Nov 1 2009, 05:42 AM said:
Yes, they are. But, O group person still present an antigen that a little different from both A and B. As the picture from this link.
http://www.ncbi.nlm.nih.gov/projects/gv/mhc/images/systemimages/ABOepitopes.jpg
I can't find the reason that they are all antigen, but different in structor. But why only O antigen that doesn't stimulate the immune system?
However, thank for your answer.
CellSpecific.com on Nov 1 2009, 09:33 AM said:
However, they still present the other type of antigen. And if you agree in this point, you will be stun by the quetion that why this type of antigen doesn't activate the immune system? Thank for your answer.
sgt4boston on Nov 2 2009, 09:21 AM said:
A or B blood introduced to a O person will stimulate a response. AB has both (universal recipient; will not produce abs to either a, b, or o. O is universal donor and will produce abs to a or b.
Thank for you answer.
All three have the H antigen -- the core structure, if you will. Since this is present in all three, this structure is tolerated (recognized as "self"), so no one's immune system reacts to it. In the A group, there is a terminal Gal attached to the H antigen, and in the B group, there is a GalNAc attached to the H antigen.
If you give type A blood to a person with type B, the immune system reacts to the foreign H+Gal structure. Similarly, if you give type B blood to a person with type A, the immune system reacts to the foreign H+GalNAc structure. However, you can give O blood to either person, because the H antigen is not foreign, it exists in all three blood types, and thus is "self" as far as the immune system is concerned.