Blood Transfusion and Agglutination

[Infarious]

I understand the ABO and Rhesus systems quite well but I don't understand why O is the universal donor if O contains anti-A and anti-B antibodies. Wouldn't it agglutinate A, B and AB type blood? Or is the agglutination negligible? Or are antibodies removed from blood destined for transfusion?

[mith]

O has neither, AB has both

[biohazard]

O lacks the A and B surface antigens, therefore the receiver's immune system does not destroy thehse blood cells. O blood does have A and B antibodies, but since the volume transfused is usually relatively small, the little amounts of antibody that are transfered to the recipient are not a big problem. However, as far as I have understood, in big operations or when there has been a massive loss of blood, matching type of blood is always the optimal choice, and only if it is not possible, O type is given.

[Revenged]

I understand the ABO and Rhesus systems quite well but I don't understand why O is the universal donor if O contains anti-A and anti-B antibodies. Wouldn't it agglutinate A, B and AB type blood? Or is the agglutination negligible? Or are antibodies removed from blood destined for transfusion?

the anti-A and anti-B antibodies are found in plasma...

plasma is separated from red blood cells by centrifugation...

only the O red blood cells are transfused (not the plasma)...

in clinical practice you'd always match blood types as it is not possible to fully separate plasma and red blood cells...

[Infarious]

Thanks Biohazard and Revenged.

[biohazard]

Good you specified my answer a bit, Revenged.

It is indeed so that the antibodies are found in the plasma (and on the surface of B-cells in the form of a membrane-bound immunoglobulin), but since both are separated from the red blood cells, it is not a big problem. Tiny amounts of both plasma and white blood cells (including B lymphocytes) usually remain among the erythrocytes, but like I tried to say, the amount is so small that usually it causes no harm. Despite this, in big transfusions this can have an effect, if O blood is given to a non-O recipient.

[mcar]

Antibodies are needed to be removed.

[biohazard]

As far as I know, the antibodies remaining within the erythrocytes need not be removed, and I'm not even sure if there is an efficient / cost effective way of doing that. After all, virtually all antibodies are removed when the plasma is separated. Any antibody traces remaining with the red blood cells should not be a problem. At least during some smallish operation requiring a unit or two of red blood cells, whatever antibodies there are with them is not a problem. And like I said before, in bigger operations a matching type of blood is used if available.

Want to specify a bit what you meant with this 'need to be removed'? :)