the BLOOD group

The Blood Group------------------Experiments with blood transfusions, the transfer of blood or blood components into a person's blood stream, have been carried out for hundreds of years. Many patients have died and it was not until 1901, when the Austrian Karl Landsteiner discovered human blood groups, that blood transfusions became safer.Mixing blood from two individuals can lead to blood clumping or agglutination. The clumped red cells can crack and cause toxic reactions. This can have fatal consequences. Karl Landsteiner discovered that blood clumping was an immunological reaction which occurs when the receiver of a blood transfusion has antibodies against the donor blood cells.Karl Landsteiner's work made it possible to determine blood types and thus paved the way for blood transfusions to be carried out safely. For this discovery he was awarded the Nobel Prize in Physiology or Medicine in 1930


All humans and many other primates can be typed for the ABO blood group.Basically,there are four principal types: A, B, AB, and O.  There are two antigens and two antibodies that are mostly responsible for the ABO types.Very often,an individual’s type is determined by  the specific combination of these four components. Individuals with type O blood do not produce ABO antigens.  Therefore, their blood normally will not be rejected when it is given to others with different ABO types.This results that type O people are normally named as universal donors for transfusions.Despite being an universal donors,they can receive only type O blood themselves. 
Another exception is that those who have type AB blood do not make any ABO antibodies.Hence,Their blood does not discriminate against any other ABO type.  Consequently, they are universal receivers for transfusions, but their blood will be agglutinated when given to people with every other type because they produce both kinds of antigens.



By a few drops of blood,you could determine an individual’s ABO type.
Mixed some of the blood with a serum containing anti-A antibodies. Another serum with anti-B antibodies is mixed with the remaining sample.Based on theory of blood group,whether or not agglutination will occur in either sample indicating the ABO type.  It is a simple process of elimination of the possibilities.  For instance, if an individual's blood sample is agglutinated by the anti-A antibody, but not the anti-B antibody, it means that the A antigen is present but not the B antigen.  Therefore, the blood type is A.

Special Thanks to :
http://nobelprize.org/educational_games/medicine/landsteiner/readmore.html
http://anthro.palomar.edu/blood/ABO_system.htm



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