Take the 2-minute tour ×
Biology Stack Exchange is a question and answer site for biology researchers, academics, and students. It's 100% free, no registration required.

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...

share|improve this question

4 Answers 4

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.

share|improve this answer
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?? –  Annette Black 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.... –  Annette Black 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.

share|improve this answer
(http: // anthro.palomer.edu/blood/ABO_system.htm) well the table given here states the presence of both the antibodies anti a and anti b in a person with blood group O. –  Annette Black 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.

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

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

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.