Image credit: Amy Claxton
One of the crucial needs that arise during or after a devastating natural disaster is the availability of the “universal” blood type O. The increased demand for blood surges following the aftermath of a catastrophe. Storms, hurricanes, and earthquake calamities are major causes of an abrupt call for blood donations. Researchers from the University of British Columbia headed by Stephen Withers knew so well the gravity of this need that they are adamant in finding a way to somehow curb the limitations hampering the availability of a universal, friendlier blood type. Withers and his team recently identified a potential enzyme candidate that appears to be efficient and at the same time cost-effective in converting blood types into type O.
Blood group systems overview
The blood is the circulating fluid in our body that performs multifarious functions. Its major functions are for transporting nutrients, delivering oxygen, moves metabolic byproducts for excretion, providing immune defense, and homeostasis. It is comprised mainly of plasma (55%) and cellular elements (45%) (e.g. red blood cells and white blood cells). The red blood cells (RBCs) are the major cellular component of the blood and are essential for their role in delivering oxygen throughout the body. The white blood cells (WBCs), in turn, are involved in the detection of non-self particles (antigens) and the subsequent immune action against them.
Blood type (or blood group) is a classification system used to identify which type the blood belongs to. It is determined based on the presence (or absence) and types of antigens present on the cell surface of the RBCs. Various blood classification systems are used to classify types; however, the ABO and the Rh systems are the most important ones. The ABO system is used to classify blood into types A, B, AB, and O. The Rh system, in turn, is used to denote blood as either positive (+) or negative (-) based on the presence and absence of the Rh factor, respectively.
Why type O blood?
Type O blood is considered as the universal blood because it has neither A nor B antigens on the surface of the RBCs. Type AB blood, in contrast, has both A and B antigens. If A antigens are present on the cell surface of the RBCs, the blood is typified as type A whereas type B has B antigens. Determining the blood group is important because blood administered into the body that does not match with the innate blood type can trigger an immune response. Transfusion involving a blood type different from one’s own can instigate the WBCs of the body to attack the transfused blood cells, and this could lead to serious effects. Thus, an individual with type A (Rh-), for instance, can receive transfusions of type A (Rh-) and type O (Rh-). Based on this precept, type O (especially Rh-) can be administered to any blood type.
Metagenomics for creating a universal type of blood
Blood banks constantly need type O. Withers and his team focused their research works in searching for enzymes that can convert types A and B to type O by applying metagenomics. Accordingly, they found enzymes from the human gut that apparently can turn type A and B into O as much as thirty times more efficiently than previously identified enzymes.1 Withers said, “We have been particularly interested in enzymes that allow us to remove the A or B antigens from red blood cells. If you can remove those antigens, which are just simple sugars, then you can convert A or B to O blood.”
In reaching their goal, they focused on mucins, which are glycoproteins secreted by the mucous membranes in the gut wall. These mucins in the gut wall display a number of sugars, including antigen A and antigen B. They found that the gut microbiome can cleave these sugars from the gut wall and use them as a food source. Using metagenomics, they identify genes from these gut microbial species that code for proteins that cleave target antigens on the cell surfaces of RBCs. Thus, type A blood, for instance, can be converted into type O blood through the enzymes that remove antigen A from the RBCs. The goal is to identify the most economical, most efficient, and safest enzyme that can be used to turn donated blood into a particular type as needed.
Disastrous events take so much of human properties and lives. Apart from the apparent destruction of homes and livestock as an aftermath of natural calamities, blood donations become crucial to save the lives of the people needing blood transfusions. Suddenly, life takes a stance on the edge between survival and death. Blood transfusions have to be extensive, safe, and economical. Although research on how to turn blood types into a more universal type has still a long way to go before it can be approved for medical use, this is a significant development.
— written by Maria Victoria Gonzaga
1 American Chemical Society. (2018, August 21). Gut bacteria provide key to making universal blood (video). American Chemical Society.. Retrieved from https://www.acs.org/content/acs/en/pressroom/newsreleases/2018/august/gut-bacteria-provide-key-to-making-universal-blood-video.html?-ga=2.17288057.1746138702.1535160738-1328130083.153516073