IH ABO Blood Group System

• Discovered the ABO Blood Group System in 1902 - Karl Landsteiner
• Landsteiner performed the first forward and reverse ABO groupings by mixing the red cells and serum together of him and his five co-workers
• ABO group contains antigen on red cells and the reciprocal agglutinating antibodies in the serum of the same individual
• Forward grouping (front type) - Defined as using known sources of commercial antisera (anti-A, anti-B) to detect antigens on an individual’s RBCs.
• Reverse grouping (back type) Defined as detecting ABO antibodies in the patient’s serum by using known reagent RBCs, namely A1 and B cells to determine the type in the patient’s serum
• There is always an inverse reciprocal relationship between the forward and reverse type
• If the individual has A antigens only on their red cells, there will be an “expected” naturally occurring anti-B antibody in their serum

  since they lack the B antigen.
• These antibodies have been described as naturally occurring because

  they are produced without any exposure to RBCs. The ABO antibodies are predominantly IgM, and they activate complement and react at room temperature or colder.
• Forward Grouping - Use of known commercial antisera (anti-A & anti-B) to determine antigens on patient’s or donor’s cells
• in forward grouping, Reagents are either made from hyper-immunized human sources, or monoclonal antibodies
• Where is the reagent of forward grouping made?

  Hyper-immunized human sources, or monoclonal antibodies
• ABO Forward Grouping

  • Anti-A = 0
  • Anti-B = 0
  • blood group = ?

  Blood type O
• ABO Forward Grouping

  • Anti-A = agglutination
  • Anti-B = no agglutination
  • blood type?

  blood type is A
• ABO Forward Grouping

  • Anti-A = 0
  • Anti-B = 4+
  • blood type?

  blood type B
• ABO Forward Grouping

  • Anti-A = 4+
  • Anti-B = 4+
  • blood type?

  blood type AB
• Blood type that has no antigen since we are testing RBC; no antigen-antibody reaction

  Blood type O
• Has antigen on the RBC in which anti a,b,and ab reacts with it

  blood type AB
• what specimen is used in reverse grouping?

  serum
• this grouping does not detect in neonate?

  reverse grouping
• why does reverse grouping not detected in neonate?

  since antibodies during that age is not detectable
• Wheter they are IgG or IgM, ABO antibodies can activate complement readily
• IgM antibodies are the associated anti-A and anti-B; it is produced in the first years of life by sensitization to environmental substances
• IgM antibodies happens during pregnancy
• Almost all normal healthy individuals above 3 to 6 months of age have “naturally occurring antibodies” to the ABO antigens that they lack. These antibodies are termed naturally occurring because they were thought to arise without antigenic stimulation.