Human blood groups-
on the presence and absence of antibodies, the blood is classified into different groups.Two types of blood groups — ABO Blood Group and Rh Blood Group (Rh Factor) are widely used all over the world. Blood group can be defined as the serological classification of blood according to the presence or absense of agglutinogen in RBC and agglutinin in plasma .
ABO Blood Group System-
ABO blood groups in human beings was first reported Karl Landsteiner . A, В and О blood groups were discovered by Landsteiner (1900). while AB group was discovered by de Castello and Sturli (1902).
In the case of the ABO blood groups, the antigens are present on the surface of the red blood cell, while the antibodies are in the serum.
'O' Blood group individuals are said to be universal donors, because their blood can be used for transfusion in individuals who have any one of the four blood types. On the other hand, individuals with blood type A can only donate to either type A or type AB, and individuals with blood type B can only donate to B or AB types. AB individuals can only donate to type AB. But AB blood group individual can accept all groups of individuals and so these persons are called universal recipients .