Soon after birth, newborns develop anti-A and/or anti-B antibodies but not the anti-Rh antibody. Unlike ABO system, an Rh -ve person will not have anti-Rh antibody in the blood unless he/she has been previously exposed to Rh +ve blood. A 'positive' blood group means that the person has Rh antigen on the red blood cells whereas a 'negative' blood group means that the Rh antigen is absent on the red blood cells. The positive or negative in the blood group refers to the Rh antigen. Blood group 'O' means absence of both 'A' and 'B' antigens and both anti-A and anti-B antibody in the plasma. A person with 'AB' blood group will have both 'A' and 'B' antigens on the red blood cells and none of the above mentioned antibodies in the plasma (neither anti-A nor anti-B antibody). Similarly, a person with 'B' blood group will have 'B' antigen on the red blood cells and anti-A antibody in the plasma. There are numerous other less important antigens and therefore numerous other blood grouping systems.Ī person with 'A' blood group will have 'A' antigen on the red blood cells and anti-B antibody in the plasma. Rh antigen determines the Rh blood group system category. ABO blood group system is determined by the presence of A and B antigen. It is important to note that the two are two different blood group systems that are quoted in combination. These two are the most important blood grouping systems and are based on the three most important antigens, i.e. Basic of ABO and Rh Blood Group SystemĪBO blood group and Rh blood group is determined by the presence of three antigens ('A' and 'B' for ABO system, 'Rh' for Rh system).

This article will give you a basic understanding of blood group, especially of O-negative blood group.

One of the components of this attack is antibodies ( special class of molecules that bind to antigens and helps immune system eliminate foreign antigens and the cells bearing them). However, any foreign antigen will not be recognized as native and an immune response will be generated to eliminate the foreign antigens. Human body recognizes its own antigens and the immune system normally will not attack own antigens ( and thus the cells bearing these antigens). The 'antigens' are special molecules that can elicit an immune response. Blood group is determined by the presence of antigen(s) on the membrane of red blood cells.

Type o negative band