We change any blood group to the first
An enzyme capable of modifying red blood cells and changing blood group has been obtained
Biochemists from the University of British Columbia and the Center for Blood Research (Vancouver) using the method of directed evolution have created an enzyme capable of modifying human red blood cells and "turning" all blood groups into the first.
Scientists led by Professor Jayachandran Kizhakkedathu have created a modified version of glycosyl hydrolase, which allows removing A and B antigens from the surface of red blood cells in human blood. With its help, it became possible to change the blood group from A0/AA (second), B0/BB (third) and AB (fourth) to 00 (first) in laboratory conditions.
The enzyme was obtained by introducing mutations into the coding gene of a bacterial enzyme found in Streptococcus pneumoniae pneumococcus. Then several cycles of directed evolution were carried out, during which the enzymes that best cope with their task were selected. After five generations, the enzyme has become more than 170 times more effective in deactivating antigens A and B than its natural counterpart.
The first blood group (00) is very important for medical purposes, as it is a "universal donor" – it can be transfused to patients with any other blood group (in the first approximation). The availability of reliable technology for turning an arbitrary blood group into the first one is potentially able to solve the problem of the ever-increasing shortage of donor blood in medical institutions.
The typology of AB0 blood groups was proposed by Karl Landsteiner in 1900. He found that on the surface of red blood cells in some people there are substances-antigens (agglutinogens), which are deposited by certain antibodies (agglutinins) contained in blood plasma. He designated the antigens with the Latin letters A and B, and the antibodies to them – alfa and beta.
There are usually no antibodies to one's own red blood cells in human blood, however, when transfused, other people's red blood cells may be incompatible and an agglutination reaction will occur. As a result, blood clots that overlap the vessels may form. The totality of the body's reactions that occur during the transfusion of incompatible blood is called hemotransfusion shock.
Even in people who do not have antigens A and B, however, innate antibodies to them are contained in the blood plasma. Therefore, transfusion of blood from one person to another often leads to hemotransfusion shock. This happens if red blood cells containing A- or B-antigens are injected into people who have antibodies to them in the body. Therefore, during blood transfusion, it is necessary to prevent the formation of pairs A-antigen-alfa-antibody and B-antigen-beta-antibody, which are called of the same name.
The erythrocytes of the first blood group have neither A nor B agglutinogens, therefore it is also called zero, and the plasma contains alpha and beta agglutinins. These features allow it to be transfused to carriers of other groups. Donors for the owners of the first group can only be themselves.
The study is published in the Journal of the American Chemical Society: Kwan et al., Towards Efficient Enzymes for the Generation of Universal Blood through Structure-Guided Directed Evolution.
In the same issue of the magazine, you can read the press release Transforming all donated blood into a universal type with a popular presentation of the work - VM.
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30.04.2015