BLOOD GROUPS

We have all heard of blood groups A, B, AB and O. A good number of you actually know which group you belong to. What is the reason of this variance? The red blood cells are part of the composition of blood. This tiny cells have three different types of sugars that are the distinguishing feature between blood types. Yes. You had me right. Sugars are the reason for all this fuss. The three culprits go by the names L-fucose, N-acetyl-D-galactosamine and D-galactose. All four blood types (AB, A, B and O) have L-fucose on their surfaces. If no other sugar is attached to the red blood cells except L-fucose then they are identified as type O. Type A red blood cells have both L-fucose and N-acetyl-D-galactosamine while type B red blood cells have both L-fucose and D-galactose. Type AB have all the 3 sugars attached. Cool stuff, right? These sugars are antigenic which means they are capable of eliciting an immune response. For example, if type A blood is transfused to a patient of type B blood, the N-acetyl-D-galactosidase sugar in the transfused blood is viewed as a foreign agent since it does not exist in type B blood cells. Foreign agents are treated as threats by the body’s immunity and therefore the transfused blood is attacked and made to agglutinate (clump together) forming a clot which may cause blockage to vessels resulting into an embolism or stroke. Since all blood types have L-fucose, O-type blood may be used for transfusions for persons of any blood type. Type AB red blood cells have all three determining sugars and making it possible for the patient of this status to receive blood from all other groups. The +/- sign on your blood group indicates your Rhesus factor. Rhesus factor is an antigenic protein also found on the surface of red blood cells. If you have the protein, you are Rhesus positive and the reverse is also true. Below is a simple illustration of red blood cells and their antigens in relation to their blood groups.

Blood donation is a noble act, whether you did it out of desire to save a life or from that compelling urge to trade your blood for that soda and half a loaf treat back to when you were in school, you made a solid difference in someone’s life. If you can, donate blood at least once a year and save another life.