In search of the universal O

Researchers from the University of Copenhagen have described a method of converting blood from groups A, B and AB into the 'universal' O blood group using bacterial enzymes.

The method, published today in Nature Biotechnology, uses recombinant enzymes to remove cell-surface sugars that trigger an immune reaction against A and B antigens in unmatched recipients.

Plasma of blood group A individuals contains naturally occurring antibodies to the B antigen. Blood group B contains antibodies to the A antigen, blood group AB has neither antibody and blood group O plasma has both.

Because group O red blood cells lack both A and B antigens, they can be transfused safely into recipients of any blood group.

Henrik Clausen and colleagues describe how enzymes from two glycosidase gene families can be used to remove the antigens and render A, B and AB red blood cells as group O cells, as assessed by standard tests.

One enzyme is from Elizabethkingia meningosepticum and targets the N-acetyl-galactosamine sugar, thus removing the A antigen. The other is derived from the gut bacterium Bacteroides fragilis and is used to cleave galactose from B red blood cells.

Importantly, the process uses routine cell washing methods that the researchers say could be scaled up to automated full-unit conversions.

The next step in the development of this technology is clinical trials to determine whether universal blood produced by this method is safe and effective. Clausen's team is working with US company ZymeQuest on the clinical trials.

Source: "Bacterial glycosidases for the production of universal red blood cells", Nature Biotechnology (DOI: 10.1038/nbt1298)