ih 2.1

• RhD is critical to pretransfusion and prenatal testing
• Rh has specific RBC antigen D and 61 different antigenic specificities
• Rh is the 2nd most immunogenic
• Antibodies against Rh are produced only after exposure
• Rh positive individuals have the D antigen, while Rh negative individuals lack or do not have the D antigen
• 1939: Levine & Stetson - Woman received blood from husband & suffers AHTR
• Rh System Nomenclature:
• Comparison of Fisher-Race, Weiner, Rosenfield, and ISBT Nomenclature systems
• Expressions related to WEAKENED D ANTIGEN EXPRESSION


  • Weak D/Du
  • Del
  • Genetic Weak D
  • D mosaic
  • Partial D
  • C trans to D
  • Test for Weak D
• WEAKENED D ANTIGEN EXPRESSION
• Weak D/Du: Extremely low number of D antigen that can't be detected by Anti-D antisera, caused by mutation of RhD gene, common in Asians
• Genetic Weak D: D antigens are complete but fewer in numbers and can't be detected by Anti-D antisera
• D mosaic: One or more parts of D antigen are missing, patient is Rh+ with anti-D to the missing part, donor is Rh-
• C trans to D: Positional effect or gene interaction effect, allele carrying D is trans (opposite haplotype) to the allele carrying zc, donor is Rh+
• Test for Weak D

  INDIRECT ANTI-HUMAN GLOBULIN TEST (IAT), Individual with weak D should be reported as Rh+, during donation or transfusion: If acting as recipient: Rh-, If acting as donor: Rh+
• Rh NULL SYNDROME: Individual lacks all Rh antigens in RBC, negative to high prevalence antigen (LW, FY5, SSU), only Rh null should be transfused, disorder: Mild Compensated HA, various symptoms like reticulocytosis, stomatocytosis, etc.
• Rh mode: reduced expression of all Rh antigen
• Rh null versus Rh mode: Rh null lacks all Rh antigens, Rh mode has normal RHAG gene but can have mutated RHCE or deleted RHD
• Rh ANTIBODIES: Most are IgG, do not bind complement, caused delayed HTR, 2nd most common cause of HDN, crosses placenta
• ANTI-LW: Reacts with Rh+ & Rh- dce except Rh null, appears as autoantibodies but not clinically significant, distinguish from Anti-D by treating panel cell with 0.2 DTT, test patient serum to Rh+ and Rh- cord blood cells
• To distinguish Anti-D and Anti-LW


  1. Treat panel cell with 0.2 DTT (LW antigens are denatured but D antigens are not affected)

  2. Test patient serum to Rh+ and Rh- cord blood cells (Anti-LW reacts to all cord blood cells but Anti-D reacts only with Rh+ cord blood cells regardless of the Rh type except Rh null)
• Rh blood group is highly complex, and alloimmunization to Rh blood group antigens can complicate transfusion and pregnancy
• Rh blood group is critical in pretransfusion and prenatal testing
• Rh blood group has specific RBC antigens (D) and 61 antigenic specifications
• Rh blood group is second in importance to ABO blood group systems in transfusion due to being very immunogenic
• Rh antibodies are produced after exposure to foreign RBCs, leading to hemolytic disease of the fetus and newborn (HDFN) and hemolytic transfusion reactions
• Rh-positive indicates that an individual’s red blood cells possess the D antigen, while Rh-negative indicates the lack of the D antigen
• Levine & Stetson reported a hemolytic transfusion reaction in an obstetrical patient


  1939
• Landsteiner & Weiner discovered Rh antibodies from guinea pigs and rabbits transfused with Rhesus Macaque monkey RBCs


  1940
• Levine and coworkers found that agglutinin causes hemolytic transfusion reaction, leading to human-produced Rh antibodies


  1940
• Anti-LW (Anti-rhesus) antibodies were formed by animals

  Mid-1940s
• Molecular testing defined the structure of RH genes


  1980
• Phenotype is defined by the serologic detection of antigens using specific antisera
• Genotype refers to an individual’s actual genetic makeup, including RH genes inherited from parents
• Basis of the name of Rh antibody is Rhesus Macaque Monkey
• Fisher-Race DCE terminology is based on the theory that antigens of the system are produced by three closely linked sets of alleles that each gene is responsible for producing a product on the RBC surface
• Rhnull genotype may be written in (-/-) or (--/--)
• Gene that codes for the presence of Rh D is ONE GENE (RHD)
• Chromosome code for RHAG is C1p
• Minimum amount of Rh-positive red cell that can stimulate antibody production is 0.1 ml