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According a summary in Chemical & Engineering News of a much more technical paper in the Journal of the American Chemical Society (referenced in the C&EN summary):
Hospitals keep stores of universal, type O blood for situations when a patient with an unknown blood type needs an emergency transfusion. The other types—A, B, and AB blood—can trigger a potentially fatal immune response in an unmatched recipient. Now, bioengineers have taken a step on the path toward making all blood universal—by broadening an enzyme’s ability to remove antigens on the surface of red blood cells (J. Am. Chem. Soc. 2015, DOI: 10.1021/ja5116088).
The quest for universal blood has tempted researchers since the discovery in the 1980s of coffee bean enzymes that could turn type B blood into O. The four main blood types each have distinctive sugar chains on the surface of their red blood cells.
Soylentils will note the intersting link to coffee.
Meanwhile, other scientists have claimed to have developed an enzyme that convert other blood types to that of the universal donor.
“We produced a mutant enzyme that is very efficient at cutting off the sugars in A and B blood, and is much more proficient at removing the subtypes of the A-antigen that the parent enzyme struggles with,” said David Kwan, the lead author of the study and a postdoctoral fellow in the Department of Chemistry. Their job, however, is not yet done. Whilst the enzyme was able to remove the vast majority of antigens from type A and B blood, they were not able to remove all of them. As the immune system is incredibly sensitive to blood groups—so much so that even small amounts of residual antigen can trigger an immune response—the scientists must first be certain that all antigens are absent.
(Score: 4, Informative) by sjames on Monday May 11 2015, @12:14PM
One is "too good" and not good enough. The first article is about an enzyme that removes all subtypes of A and N, but curts off too much so that what is left isn't truly type O either. It is thought that it will be removed quickly from circulation because of the missing O type antigen.
The second doesn't have that problem, but isn't able to remove some sub-types of the A antigen.
(Score: 2) by Grishnakh on Monday May 11 2015, @04:02PM
The first article is about an enzyme that removes all subtypes of A and N, but curts off too much so that what is left isn't truly type O either. It is thought that it will be removed quickly from circulation because of the missing O type antigen.
What are you talking about? The 2007 article doesn't say anything about this. And how can they cut off "too much"? Type O blood has no antigens; it's only A, B, and AB which have antigens. O people can't have the other types because they're allergic to those antigens, and the A/B/AB people *can* have O because there's no antigens in there for them to be allergic to. Unless you're talking about that "Bombay" blood type thing.
(Score: 3, Insightful) by sjames on Monday May 11 2015, @04:45PM
The articles linked from 'summary' and 'have claimed' in the summary refer to two different efforts.
At one time, O was thought to be an absence of antigen, but then they discovered Bombay.
Type O blood still has the H antigen. The A and B antigens are different additions to the H antigen. This [wikipedia.org] may make it clearer.
If I'm understanding correctly, the ober-active enzyme doesn't even leave all of Bombay's h antigen.
(Score: 2) by Grishnakh on Monday May 11 2015, @06:01PM
I see, that diagram makes a lot of sense. So even Bombay types have an antigen, it's just smaller and simpler than those for O types, and they're all composed of sugars (namely galactose). So if you use an enzyme which consumes sugars, you won't have any of those molecules on the blood cell, and quite likely the body won't be able to use the blood (because those molecules are surely there for a reason).
One thing I wonder now, though, is how many people who think they're type O are actually Bombay types. Probably a very tiny number, but still...
(Score: 2) by sjames on Monday May 11 2015, @07:31PM
Most of those should be caught by cross matching, though in extreme emergencies that step is sometimes skipped.