A team of researchers from the University of British Columbia has isolated an enzyme in the gut that reliably converts any type of blood into type O, which is compatible with nearly everyone.

These enzymes are able to remove markers called antigens from AB, A and B blood.

Approximately 7%–8% of the UK population has type O negative blood, but demand for this special group accounts for about 13% of all hospital requests, according to NHS Blood and Transplant.

Blood groups

There are four basic types of blood group, AB, A, B and O, and each group is characterised by the presence of antigens, which are sugars on the surface of the cells.

Type A blood has A antigens, type B blood has B antigens, type AB has both, and type O has no antigens.

Someone with type A blood cannot receive type B blood and vice versa, because the body will produce antibodies to attack red blood cells with antigens different to its own.

However, people with type AB blood (‘universal recipients’) are able to receive any type of blood because their red blood cells have both A and B antigens, so their bodies will not produce antibodies.

Type O blood is often called the ‘universal donor’, as the red blood cells do not have antigens.

This type, specifically type O negative (which is the true universal donor), is the most valuable because it can be administered to virtually everyone and is particularly useful in emergencies when the blood type of patients is often unknown.

Research progress

Using a technique called metagenomics, the team was able to take a large amount of microbes from a sample of human faeces and ‘get a snapshot of all the DNA’ found in the gut.

The team then isolated bacterial genomes from the sample and tested thousands of enzymes against sugary proxies that resembled A and B antigens.

One enzyme was found to be particularly effective at stripping away A antigens from red blood cells.

Researchers were then able to combine their new enzyme with one that is already known to remove B antigens from blood cells, providing a way to convert AB, A and B blood into type O.

The researchers hope to continue exploring their new approach to blood-type conversion in clinical trials to test the effects on the human body.

If successful, this approach could help alleviate the near-constant shortage of blood around the world.

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