ABO Blood Group System

• The ABO system is the most important of all blood groups in transfusion practice
• ABO is the only blood group system in which individuals have antibodies in their serum to antigens that are absent from their RBCs
• In 1901, Landsteiner drew blood from himself and five associates, separated the cells and serum, and then mixed each cell sample with each serum
• Landsteiner was inadvertently the first individual to perform forward and reverse grouping
• Forward grouping or front type is defined as using known sources of commercial antisera

  (anti-A, anti-B) to detect antigens on an individual’s RBCs
• The principle of Forward grouping is the detection of antigens on patient's RBC with known commercial antisera
• Commercial antiseras:

  • Anti-A → Blue
  • Anti-B → Yellow
  • Anti-D → Colorless
• A) Type O

  B) Type A

  C) Type B

  D) Type AB

  
• Slide method only use forward grouping

  
• Tube method uses both forward and reverse grouping

  
• Reverse grouping or back type is defined as detecting ABO antibodies in the patient’s serum by using known reagent RBCs, namely A1 and B cells
• • Forward grouping = Patient’s RBC + Anti-Sera
  • Reverse grouping = Patient’s Serum + Known reagent RBCs
• The principle of Reverse grouping is the detection of ABO antibodies (isoagglutinins) in serum of patients with known commercial RBCs
• ABO antibodies is also known as Isoagglutinins
• A) Type O

  B) Type A

  C) Type B

  D) Type AB

  
• Blood group O

  
• Blood group A

  
• Blood Group B

  
• Blood group AB

  
• The expression of certain RBC antigens may diminish in strength during storage, particularly in EDTA and clotted samples. Better results will be obtained with fresh samples
• Excessive agitation may disrupt weak agglutination and produce false negative results
• Excessive centrifugation can lead to difficulty in re-suspending the cell button, while inadequate centrifugation may result in agglutinates that are easily dispersed
• False positive or false negative results can occur due to:

  • Contamination of test materials
  • Improper reaction temperature
  • Improper storage of materials
  • Omission of test reagents and certain disease states
• Suppressed or weak expression of blood group antigens may give rise to false negative reactions