Gut bacteria enzymes can eliminate antigens found in blood types A and B, leading to improved compatibility with blood type O.
According to Live Science, Swedish scientists have recently successfully tested a method using gut bacteria enzymes to enhance compatibility between blood types.
Blood type in the human body is determined by specific antigens present on the surface of red blood cells. Antigens consist of sugar molecules and proteins that coat the cell surface.
Mismatched blood transfusions can lead to fatal immune reactions. (Illustration: Live Science)
In a study published on April 29 in the journal Nature Microbiology, researchers from Lund University (Sweden) identified specific extended sugar chains present in red blood cells (RBCs) that prevent individuals with certain blood types, such as A, from donating or receiving blood from someone with a different blood type. After identifying these chains, scientists used a mixture of enzymes from the gut bacterium Akkermansia muciniphila to remove those antigens from RBCs.
According to Dr. Martin Olsson, a hematology and blood transfusion specialist and one of the lead authors, the surface of red blood cells has a structure similar to the mucus in the human intestine. Therefore, rather than synthesizing artificial enzymes, scientists employed gut bacteria enzymes that metabolize the mucus on the surface of red blood cells.
For decades, scientists have attempted to use enzymes to remove antigens from blood types A and B. However, previous experiments have all failed.
In the 1980s, scientists discovered an enzyme from unroasted coffee beans to convert blood type B to blood type O. After removing known antigens from the red blood cells, blood type B appeared molecularly similar to type O. However, when mixing treated blood with type O plasma, incompatibility was observed. This incompatibility arose because the scientists had only removed known antigens, while the extended sugar chains present in the red blood cells remained.
In the new study, Dr. Olsson and colleagues demonstrated that removing antigens and extensions from blood samples A and B made them more compatible with blood type O.
The results of Dr. Olsson’s team showed that after treatment with gut bacteria enzymes, approximately 80% of plasma from blood type B donors was compatible with type O plasma. This compatibility increased to about 91% to 96% after the extended sugar chains were removed.
However, the success rate of compatibility for blood type A was more modest, starting at 20% and increasing to 50% after the removal of extended sugar chains.
According to Dr. Steven Spitalnik, co-director of the Blood Transfusion Biology Laboratory at Columbia University, blood type A appears to be biochemically more complex than blood type B. Thus, scientists will need to adjust the type of enzyme for more precise screening.
According to scientific guidelines, mismatched blood transfusions can lead to fatal immune reactions. This is because the immune system in the body recognizes and activates an attack on foreign antigens present in red blood cells. Antigen A in blood type A is incompatible and cannot mix with antigen B in blood type B. Meanwhile, blood type O—the most common blood type for donations—lacks these specific antigens. Therefore, it can be given to individuals of any blood type.
Although people with blood type O are considered the most common donors, this blood type is not always sufficient to meet the needs of recipients. Thus, finding a way for anyone with any blood type to donate to others helps reduce the risk of blood shortages.
In September 2023, the American Red Cross announced a nationwide blood shortage, citing extremely low blood supply levels that had dropped nearly 25% since early August. A year earlier, the NHS Blood and Transplant Agency in the United Kingdom issued an amber warning, indicating shortages of red blood cells in many blood types and that reserves could drop further without action.
