ABO Blood Group System

ABO Blood Group System

• Antigens on red cell membranes are unique to the individual, recognized as foreign if transfused into another individual, and promote agglutination of red cells if combined with antibody.
• Presence or absence of these antigens is used to classify blood groups.
• Major blood groups include ABO and Rh.
• ABO blood group was discovered by Karl Landsteiner in 1901 and is the most significant for transfusion practice.
• ABO blood group consists of two antigens (A and B) on the surface of RBCs and two antibodies in the plasma (anti-A and anti-B).

ABO Typing Techniques

• There are two ABO typing techniques: slide method and tube method.
• Slide method requires monoclonal Anti-A and Anti-B reagents.

Rh Blood Group System

• Rh blood group system is the second most important blood group system after ABO.
• The term Rh derives from Rhesus monkey.
• Rh blood group system is one of the most polymorphic and immunogenic systems.
• D (Rh) antigen is the most potent and is present on the erythrocytes of approximately 85% of the human population.
• Human red blood cells are classified as Rh positive (Rh+) or Rh negative (Rh-) depending on the presence or absence of the D antigen.
• Other common Rh antigens include C and c, and E and e.
• Patients are not routinely typed for these antigens unless they have developed atypical antibodies or require long-term transfusion support for diseases such as myelodysplasia or sickle cell disease.
• There are more than 50 other Rh system antigens known in addition to the five principal antigens (D, C, c, E, and e).