Thursday, April 05, 2007

Blood shortages to be passé?

Hallelujah! Blood shortages may be passé!

Such were the headlines this past week with a flurry of news items about bacterial enzymes that can cut antigen-bearing sugar molecules from the surface of red blood cells. The enzymes can render A and B rbc into group O rbc, producing so-called "universal donor" cells that can be transfused to recipients of any ABO group, providing the rbc are Rh-negative and providing recipients lack unexpected antibodies.

The news was based on this recent publication by Danish researchers:

Was it really news given that the concept has been around for about 25 years? For example:

Editorials back then were similar to today:
Cowart VS. Green coffee beans may solve a blood bank problem. JAMA 1982 Jan 1;247(1):12.

Similar research followed in the 1990s:

Looking back, I think that I first became aware of the possibility of enzymes to cleave ABO blood group antigens in this 1994 paper and accompanying editorial:

These early papers made nice discussion papers for students as they dealt with enzymes from coffee beans, soybeans, and taro (novelty) and helped reinforce the sugars responsible for group A and B antigens.

My joke when teaching ABO blood group chemistry was that no one in the transfusion service ran around asking for a crossmatch for two alpha-D-galactose red cells. <8-)

One problem was that the research dealt with converting B cells into group O red cells (stripping the terminal alpha-D-galactose) and would be more useful if A rbc could be converted using a naturally occurring alpha-N-acetylgalactosaminidase, since group A has a higher frequency in Western Europe and North America.

Another was that the research could not be applied to large scale production despite in vivo studies such as this one:

In a way, the current headlines remind me of the unmet promise of "artificial blood substitutes" (perfluorocarbons and hemoglobin-based oxygen carriers) whose history dates back to the 1960s. We have been waiting a long time!

Many of the news items on the possibility of converting other blood groups to group O include precautions. As noted by Ian Franklin, the national medical and scientific director of the Scottish National Blood Transfusion Service, in the Scotsman:

Quite an understatement by Dr. Franklin. Moreover, the conversion process would need to be cost-effective when applied to large-scale production (millions of blood donors annually).

So, will blood shortages may be passé any time soon? My guess is that this French saying applies:

Keep on donating!

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