[thedoc (OP)]

Kaya Kwinana  asked the Naked Scientists:
   Chris
From your explanation of why animal blood could not be used for human transfusion, it seems the main problem is the blood cells rather than the plasma.
Especially important seems to be the blood groups.
Since there is a blood group which is universal (I think Group O), is it not possible to get those cells to multiply in sufficient quantities (don't want to say in a test tube but if possible you would know where) to plug the supply gap?
Regards
Kaya Kwinana
 
What do you think?

[chris]

Blood "groups" arise because red blood cells have on their surfaces collections of sugar molecules - called antigens - that are recognised by the immune system. If blood is transfused into an individual with mismatched antigens then the recipient's immune system will regard the cells as hostile and mount a response. Initially this involves antibodies locking onto the foreign antigens and cross-linking them. This binds the cells together in what's known as an agglutination reaction and can be fatal if the agglutinated cell mass lodges in a blood vessel and obstructs it. But administering cells with the same surface markers, or no surface markers / antigens, does not trigger this reaction and is safe. This is the difference between a compatible and an incompatible blood transfusion.

Four common "groups" are defined in humans A, B, AB and O. Other animals also have multiple blood groups: dogs have 13 different known groups, cats have 3, sheep have at least 7 and chimps appear to have 3. However, the markers or antigens that define these groups are not the same as the markers found on the surfaces of the blood cells of humans.

Therefore, it's inevitable that, in the majority of cases, the transfusion of animal blood into a human would trigger an immune response and probably fatal agglutination within minutes.

[evan_au]

it seems the main problem is the blood cells rather than the plasma.

By filtering out the red blood cells, you remove most of the antigens that your body would attack. Humans may have been exposed to some of these antigens in the past (eg from their mother), and might be ready to mount an immediate immune response.

However, the white blood cells in the animal plasma would regard your body as alien, and try to attack it. But they would have few allies, and would be overwhelmed.

There are also antibodies floating around in the animal blood. If the animal has never been in a fight with a human, then hopefully there would be no anti-human antibodies present.

But any sterile liquid which has roughly the right salt concentration would work for transfusion. It is said that in an emergency, even filtered coconut water has been used to restore some blood volume.