Normally donors and recipients of blood transfusions need to be carefully matched to avoid a transfusion reaction - an immediate antibody-antigen reaction that can result in fever, low blood pressure, low back pain, a crushing sensation in the chest, nausea, vomiting and death. There are many different blood groups, but a transfusion reaction will only occur if an individual has acquired antibodies to a different blood group through exposure to the antigen that they don't have, and are then given blood with that antigen.

The best known blood group antigens are A, B and H (the O antigen). Exposure to these antigens occur through eating food that contains antigenic components identical to the blood group that the individual does not have. Antibodies to ABO blood groups are IgM, causing destruction of transfused red blood cells, which can then block the kidneys and cause acute tubular necrosis. In unsensitised individuals the reaction may develop over days or weeks as antibodies are produced, resulting in anaemia and jaundice. Reactions to white blood cells and platelets can occur, although the consequences are less serious.

Sensitisation to the Rhesus blood group, which includes the antigens C, c, D, d, E and e, can happen before or during birth, especially with Rhesus D, if the mother is Rhesus negative and her baby is Rhesus positive.

Individuals with blood group O Rhesus negative are considered universal donors, as their red cells do not carry antigens to A, B or D. Consequently O negative blood can generally be transfused to individuals of any blood group.

It is also possible to acquire antibodies to non-self blood groups following exposure to those antigens on some non-self tissue such as a graft or incompatible blood transfusion. Examples of other blood groups involved in transfusion reactions are Kell (K, k), Duffy (Fya, Fyb, Fy) and MN (M, N). Antibodies to Rhesus and other blood groups are IgG.

Scientists at the Albert Einstein College of Medicine, New York have now found a way to 'hide' the ABO and Rhesus antigens on the donor's red blood cells before transfusion to make their blood suitable for any recipient. Using polyethylene glycol (PEG), a polymer of the hydrocarbon ethylene oxide, stuck together with thiols to stick the PEG to the amino acid lysine on the surface of the red cell. The blood from individuals of any blood group will behave as if it is from a donor of blood group O negative. PEGylation has been used in other areas of medicine, such as PEGylated interferon, which remains in the body longer, prolonging its effectiveness. PEG has been found to be immunogenic and can induce antibodies that shorten survival of transfused PEG-RBCs in rabbits, so PEGylation may not be the best way to transfuse blood.

This is not the only way to alter red blood cells to create universal donor blood. Studies have been carried out on group B blood to remove the sugar galactose on the end of the B antigen with the enzyme galactosidase. The red blood cells from group B donors were found to be comparable to group O blood for safety and efficacy. This does not overcome the problem of Rhesus incompatibility, and also the researchers are still looking for a way to convert group A blood to group O.

The laboratory-manufactured universally compatible blood is still some way off. For now, it looks like it is best to get the closest match possible, and the best way to do that is to receive a transfusion of your own blood that you have stored prior to a scheduled operation.

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References:

Nacharaju P, Boctor FN, Manjula BN, and Acharya SA.

Surface decoration of red blood cells with maleimidophenyl-polyethylene glycol facilitated by thiolation with iminothiolane: an approach to mask A, B, and D antigens to generate universal red blood cells.

Transfusion, March 1, 2005; 45(3): 374-83.

PMID:

Garratty G.

Progress in modulating the RBC membrane to produce transfusable universal/stealth donor RBCs.

Transfus Med Rev. 2004 Oct;18(4):245-56.

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Garratty G, Telen MJ, Petz LD.

Red cell antigens as functional molecules and obstacles to transfusion.

Hematology (Am Soc Hematol Educ Program). 2002;:445-62. Review.

PMID:

Kruskall MS, AuBuchon JP, Anthony KY, Herschel L, Pickard C, Biehl R, Horowitz M, Brambilla DJ, Popovsky MA.

Transfusion to blood group A and O patients of group B RBCs that have been enzymatically converted to group O.

Transfusion. 2000 Nov;40(11):1290-8.

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