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:
- Qiyong P Liu QP et al. Bacterial glycosidases for the production of universal red blood cells. Nature Biotechnology 2007 Mar;25(3):327-37.
- Goldstein J, Siviglia G, Hurst R, Lenny L, Reich L. Group B erythrocytes enzymatically converted to group O survive normally in A, B, and O individuals. Science 1982 Jan 8;215(4529):168-70.
- Dybus S, Aminoff D. Action of alpha-galactosidase from Clostridium sporogenes and coffee beans on blood group B antigen of erythrocytes. The effect on the viability of erythrocytes in circulation.Transfusion 1983 May-Jun;23(3):244-7.
Cowart VS. Green coffee beans may solve a blood bank problem. JAMA 1982 Jan 1;247(1):12.
Similar research followed in the 1990s:
- The conversion of group B red blood cells into group O by an alpha-D-galactosidase from taro (Colocasia esculenta). Carbohydr Res 1991 Sep 18; 217:191-200.
- Goldstein J, Galbraith RA. Transfusions to group O subjects of 2 units of red cells enzymatically converted from group B to group O. Transfusion 1994 Mar; 34(3):209-14.
- Wilson RB, Spitalnik SL. Designer red cells. (editorial)Transfusion 1994 Mar; 34(3):189-91.
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:
- Lenny LL, Hurst R, Goldstein J, Benjamin LJ, Jones RL. Single-unit transfusions of RBC enzymatically converted from group B to group O to A and O normal volunteers. Blood 1991 Mar 15;77(6):1383-8. (note link to full free text)
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!
I agree that this technique is a long way from being routine and used on a large scale. Clinical trials to assess the long term effects would also be important. Would antibodies be formed to neo-antigens due to the enzyme treatment?
ReplyDeleteAll other blood group antigens apart from the A/B will be present and so it will not reduce the incidence of alloimmunisation or delayed TR's for example. Plus, I think it will increase the BTS laboratory workload because all blood will need to be tested twice, before and after treatment, to ensure that no A/B antigens are left on the cells. Cost-effectiveness will need to be carefully assessed! Although even one fatality due to an ABO incompatible transfusion is one too many, if efforts (and money) are concentrated on training and education so that ABO typing is 100% guaranteed, then this may be a wiser distribution of funds!
'ECO'cells would of course, be useful in emergency situations and in times of conflict/terrorist activities but it remains to be seen how easily the research will convert to rotuine preparation, even for these situations.