ABO BLOOD GROUPS (IH)

• ABO Blood Group System


  The only blood group system where individuals have antibodies to antigens absent from their RBCs.
• Karl Landsteiner


  First to perform forward and reverse grouping in blood typing.
• Forward Grouping


  Using antisera to detect antigens on an individual's RBCs.
• Reverse Grouping


  Detecting ABO antibodies in the patient's serum using known reagent RBCs.
• Antisera


  Monoclonal antibodies that are highly specific.
• Anti-B Sera


  Sera with a yellow color due to acriflavine dye.
• Reagent Cells


  RBCs used in blood typing, typically 4-5% of the total RBCs.
• Group O and A


  The most common blood types.
• Group AB


  The rarest blood type.
• ABO Antibodies


  Antibodies produced against A and/or B antigens absent from RBCs.
• ABO Abs


  Naturally occurring, predominantly IgM.
• Complement Activation


  Process where ABO antibodies activate complement.
• 3-6 mons


  only forward grouping on cord blood, antibodies present maybe IgG maternal
• Elderly


  has lower levels of anti-A and Anti - B, undetectable in reverse grouping
• Group O


  has anti a and anti b
• Group O


  Not a combination of anti a and anti b but is "cross-reacting"
• Group O


  IgG in nature
• Antibody Production Peaks


  Peak between 5 and 10 years of age, declining later in life.
• Production of ABO Abs

  Initiated at Birth
• Inheritance of ABO Blood Groups

  Bernstein
• ABO gene


  Chromosome 9
• Phenotype


  Group A and B
• Genotype


  AA, BO, OO
• ABO, Hh, Se genes

  Codes for glycosyltransferases
• A,B,H Ag


  formed from the precursor material (paragloboside or glycan)
• H antigen


  precursor of A and B Antigen
• H and Se genes

  located on chromosome 19
• H gene


  Must be inherited to form ABO antigens on the RBCs
• Se gene


  must be inherited to form ABO antigens in secretions
• newborn


  25-50% antigenic sites
• 2-4 yrs old


  antigenic site fully develop
• Group O


  inherits at least one H gene and two O genes.
• H gene


  a-2-L-fucosyltransferase
• a-2-L-fucosyltransferase


  L-Fucose
• Immunodominant Sugars


  Sugars conferring blood group specificity at terminal positions of precursor chains.
• Bombay Phenotype


  Phenotype lacking normal ABH antigen expression due to hh genotype.
• A Blood Group


  A gene codes for α-3-N-acetylgalactosaminyltransferase.
• α-3-N-acetylgalactosaminyltransferase


  N-acetyl-D-galtosamine
• B Blood Group


  B gene codes for α-3-D-galactosyltransferase.
• α-3-D-galactosyltransferase


  D-galactose