Gut enzyme could open door for creation of universal blood donations

Nurses attend blood donors on beds during session at NHS National Blood Service collection centre

Nurses attend blood donors on beds during session at NHS National Blood Service collection centre

TUESDAY, Aug. 21, 2018 (HealthDay News) - An enzyme found in gut bacteria could convert type A blood into universal type O blood, a scientific feat that would significantly boost blood supplies, a new study suggests.

"Blood type is determined by the presence of antigens on the surface of red blood cells; type-A blood has the A antigen, B has the B antigen, AB blood has both antigens and O blood has none", said lead researcher Stephen Withers, a professor of chemistry and biochemistry at the University of British Columbia.

"It looks like it completely converted to O", Withers said. If the antigens injected into an individual doesn't match the antigens already in the body, the immune system attacks and kills the cells - rendering the donated blood useless and even harmful.

The researchers presented their results today at the 256th National Meeting & Exposition of the American Chemical Society in Boston, Massachusetts. Such research is considered preliminary until published in a peer-reviewed journal.

For years researchers have been scrambling to find ways to adjust donated blood to a common type, however, they have not yet been able to find an efficient selective enzyme that could do the trick while still remaining safe and economical.

When lacking in blood for transfusions, going with your gut might do the trick. O blood, however, has no antigens, which makes it very valuable. Type A has A antigens, type B has B antigens and type AB has both.

Of the four basic blood groups, only type O has no antigens. "If you can remove those antigens, which are just simple sugars, then you can convert A or B to O blood".

As an example, the very same team announced back in 2015 that enzymes used by Streptococcus pneumoniae could manage this.

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Withers is now validating the enzymes with colleagues at the Center for Blood Research at UBC and testing them in larger-scale studies.

Researchers in the United States said the transformation is up to 30 times more efficient than previously studied enzymes and will soon start work on clinical trials. This is why group A blood must never be given to someone who has group B blood and vice versa. Gut bacteria are known to derive some of their energy from breaking down these sugars, Withers said.

One workaround this issue is to turn other types of blood into O-type.

"The other big key: our enzyme works on whole blood", he said.

"We don't seem to see any other sugars cut off by this enzyme".

Previous research uncovered a similar process for type B blood, but Withers said making this work with type A blood was much more important, given how common the blood type is. "As far as we can tell, we're only cutting off the A antigen".

The researchers started by looking for enzymes that can help them achieve their goals. So, in one fell swoop, they grabbed the DNA blueprints for everything those microorganisms might make - including, it turned out, enzymes that help the bacteria pluck sugar-studded proteins called mucins off the walls of the digestive tract.

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