Soon, for a blood transfusion, it may not be necessary to match the receiver’s blood type with the donor’s. Scientists at the University of British Columbia (UBC), Canada, have discovered a method to convert all blood into type O, the universal donor. Human blood is classified under the ABO group on the basis of the presence and the type of surface sugars on the RBC. Type A and Type B RBCs have an extra (but distinct, in the two cases) sugar molecule bound to the surface while type AB has both the extra molecules and Type O has neither. These molecules function as antigens or triggers of immune response—Type A blood plasma has anti-B antibodies (antibodies target antigens once directed by the immune system to respond) while Type B has anti-A antibodies. Type O has both antibodies (but no antigens, which is why it is the universal donor) while Type AB has no antibodies (making it the universal recipient).
This is not the first time that blood with lesser antigens has been produced in a lab, but the UBC researchers have discovered a technique that allows them to markedly reduce the antigen count. The technique, called directed evolution, uses bacterial DNA to produce an enzyme that snips off antigen molecules from the RBCs. After inserting a particular mutation, after 5 generations, the researchers harvested the same enzyme, only with 170 times more potency. The treated blood isn’t a perfect Type O at the moment, but the researchers believe they can tweak the enzyme to be powerful enough for that. The findings could prove to be a boon in emergencies where finding matching blood types takes up precious times. Incidentally, this can also take care of the shortage of O (Rhesus factor negative) blood in blood banks given its overuse as the universal donor.