OTHER Blood Group Systems

• ISBT OO4 Rh BLOOD GROUP SYSTEM

  • In 1939, Levine and Stetson described a hemolytic transfusion reaction in an obstetrical patient and this was the first noted RH HTR case
  • The most important blood group system associated with HDN
  • The second leading cause of HDN
  • The type of hemolysis is DELAYED AND EXTRAVASCULAR
  • RH genes are inherited as codominant alleles. The product of RH genes are nonglycosylated proteins.
• TERMINOLOGIES OF Rh System

  1. Fisher-Race (DCE)

  Fisher race antigens: D, C, E, c, e

  “d” = amorph and represents absence of D antigen, reported as Rh (-)

  Rh null phenotype= absence of all RH antigens

  RH null phenotype can be written as Rhnull, —/—, or RH: –1, –2, –3, –4, –5

  Order of Immunogenicity: D>c>E>C>e
• Wiener believed there was one gene responsible for defining Rh that produced an agglutinogen containing a series of blood factors
• Rh-Hr terminology

  Wiener believed there was one gene responsible for defining Rh that produced an agglutinogen containing a series of blood factors
• Rosenfield (Alpha numeric) assigns a number to each antigen of the Rh system in order of its discovery
• Rosenfield (Alpha numeric)

  The nomenclature has no genetic basis
• Rosenfield (Alpha numeric) antigens

  • D= Rh1
  • C= Rh2
  • E= Rh3
  • c= Rh4
  • e= Rh5
• International Society of Blood Transfusion (ISBT) adopted a six-digit number for each blood group specificity
• International Society of Blood Transfusion (ISBT) numeric terminology

  The first three numbers represent the system and the remaining three represent the antigenic specificity
• International Society of Blood Transfusion (ISBT) establishes a uniform nomenclature that is both eye and machine readable
• R0 or Dce - most commonly seen in Black people

  R1 or DCe - commonly seen in WAN (White or Caucasian, Asia, Native Americans)
• Genetic weak D - D antigens expressed appear to be complete, but few in number
• Del

  • extremely low number of D antigen that most reagent anti-D are unable to detect.
  • This phenotype occurs most often in individuals of Southeast Asian descent, occurring in up to 30% of that population. It is rare in Caucasians
• C Trans to D (Position effect)

  - The first mechanism that may result in weakened expression of D antigen was originally described as a position effect or gene interaction effect

  • Allele carrying D is trans (opposite haplotype) to the allele carrying C
• D mosaic or Partial D

  • Individual with Partial D may produce ANTI-D TO THE MISSING PART
  • One or more parts of the D antigen is missing or altered. The expression can be weakened is when one or more D epitopes within the entire D protein is either missing or altered
• TEST FOR WEAK D / Du

  Test: Indirect AHG/Coomb’s IAT

  Note: In case of Weak D (+), individually it must be reported as Rh (+)

  In case of blood transfusion/donation;

  Patient: Typed as Rh (-)

  Donor: Typed as Rh (+)
• Rh ANTIBODIES

  • Most are IgG and reacts optimally at 37’C
  • They are immune antibodies
  • Do not bind complement
  • Causes extravascular hemolysis
  • Causes delayed, extravascular HTR
  • Rh antibodies are usually produced following exposure of the individual’s immune system to foreign RBCs, through either transfusion or pregnancy
  • HDFN caused by Rh antibodies is often severe because the Rh antigens are well developed on fetal cells, and Rh antibodies are primarily IgG, which readily cross the placenta
• Anti-LW

  • Originally identified as anti-Rh in early experiment involving rabbits immunized with rhesus monkey blood
  • Anti –LW agglutinates Rh+ and Rh- cells except Rh null (--/--)
• RH null syndrome

  • Individuals lack all RH antigens on their RBCs
  • stomatocytosis,
• ♥ G is an antigen present on most D-positive and all C-positive RBC
• Saline reactive reagents

  • Saline reactive reagents, which contain IgM immunoglobulin, were the first typing reagents available to test for the D antigen
  • Because saline anti-D is an IgM immunoglobulin, it cannot be used for weak D typing.
• High protein Anti-D reagents

  • High-protein anti-D reagents (poly-specific reagent) were developed that consisted primarily of IgG anti-D
• Chemically modified

  • When samples test AB Rh-positive or when the Rh test is performed by itself, a separate saline control or 6% to 8% albumin control must be used to ensure the observed reactions are true agglutination and not a result of spontaneous agglutination.
• Rh monoclonal antibodies reagents

  • most common Rh antisera
  • It is prepared by hybridoma technology