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A person wih blood group O is called a Universal Donor. Well, his plasma contains antibodies A and B. During blood donation, if blood group O is given to a person with blood group A (since blood group O can be donated to all the blood groups) then wouldn't the antibodies of the donor with blood group O harm the recipient? Although nowadays doctors prefer giving blood having 100 percent compatibility...

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up vote 5 down vote accepted

The key feature of type O blood as "universal donor" is that the incoming red blood cells have neither A nor B antigens and so the resident antibodies (anti-A , anti-B) will not react with them. Since transfusions are carried out with packed red blood cells the plasma antibodies of the donor don't matter - they will not be introduced into the recipient.

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For plasma donation the reverse is true, O is the universal acceptor and AB is the universal donor. – AndroidPenguin Jul 9 '13 at 17:22
@AndroidPenguin What if the entire blood is donated instead of just RBC's would that affect the receiver?? Well i would also like to know why the reverse is true in case of plasma donation?? – user3800 Jul 13 '13 at 17:05
That would cause the cross reaction effects you'd imagine, and so hence neither is done – AndroidPenguin Jul 13 '13 at 17:36
ok, it really cleared my confusion thanks.... – user3800 Jul 15 '13 at 1:43

Since a person with blood group O does not express the A and B antigens, his blood does not contain antibodies to A and B. Therefore, it is safe to transfuse into someone with type A, B, AB, or O blood.

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(http: // well the table given here states the presence of both the antibodies anti a and anti b in a person with blood group O. – user3800 Jul 7 '13 at 16:37

This is because the Group A or Group B recipient's plasma contain soluble A or soluble B (antigen not bound to red cell surface). These free antigens will bind to the antibodies from the donors and prevent it to react on the red cell surface antigen A or B. The other thing is usually universal O should be low titer Anti-A or Anti-B.

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Welcome to Biology.SE. Please add one or more references to support and strengthen your answer. – Mike Taylor Sep 14 '14 at 14:47

If red blood cells have no A or B antigen on its surface it means it O blood is said Universal donor bcz no antigen antibody reaction take place the reason is that it has no antigen for any antibody

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