Blood Types
Normally we might ask others what is your blood type and refer to A, B, AB, or O, and Rh positive or negative system. But do you know we have other blood types system? There are actually 30 other ways to types blood, including two just identified by French scientists. The latest are based on proteins called Langereis and Junior. According to Biologist Lionel Arnaud of the French Institute of Blood Transfusion they're almost universal.
Making Sense of the Research
A common school science experiment is to try and determine your own blood type. (Note: Don't assume your conclusion is accurate!) You may also know your blood type from a doctors' visit or filling out medical forms. The blood types we usually hear about are A, B, AB, and O, with a positive or negative attached.These types indicate what kind of antigens, or proteins, are on the surface of your red blood cells. Type A has an antigen we call A, type B has antigen B, type AB has both, and type O has neither. The positive or negative refers to a type of Rhesus protein, specifically Rh-D, and it may be present (positive) or absent (negative).
Blood typing is important because if you receive another kind of blood or tissue – for example, a transfusion or an organ transplant – it must be compatible with your blood type. Giving type B blood to a type A person, for example, would trigger what's essentially an allergic reaction to the blood. That's because the type A person's body would recognize the B protein as a foreign invader, just like a bacteria or virus. It would attack the B-type blood with immune cells called antibodies, creating a serious and potentially life-threatening allergic reaction.
The A/B/O and Rh-D systems create eight different blood types, which represent most of the variation in blood proteins in the human population. However, as you heard, there are actually a total of 30 surface proteins that can vary from person to person. Their names include M and N, Kell, Lewis, and others, often named after the patient in which they were first identified.
The other blood types aren't as well known for one of two reasons: either the vast majority of people have one of the types (therefore making incompatibility rare), or incompatibility doesn't usually cause significant medical problems. In the case of the new blood types, Langereis and Junior, the first is true: until now, it was assumed that virtually everyone carried the proteins. But Arnaud's team found that there are small but significant populations that have Langereis or Junior-negative people – enough to classify the presence or absence of these proteins as a new blood type.
As you heard, the negative blood types are found mainly in certain populations. Therefore, for example, it may only be important to check the Junior type in people of Japanese descent. But knowing about these minor blood types could help explain some otherwise mysterious cases – for instance, women who have unexplained miscarriages. An Rh-negative mother carrying an Rh-positive baby can develop antibodies that harm the fetus, but this is widely recognized and can be prevented with certain drugs. When there's no Rh incompatibility, it's possible that a conflict in one of the lesser-known blood types could be causing the reaction.
Now try and answer these questions:
- What are the best-known blood type systems?
- Why are other blood type systems less well known?
- What does it take for a protein on a red blood cell's surface to be part of a blood type system – positive or negative?
- Why is it important to understand other blood type systems?
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