AB_SCR_ID

• Clinically Significant Alloantibodies


  Cause decreased survival of RBCs, typically IgG antibodies that react at 37°C
• Antibody Screening


  Involves the reaction between patient serum with 2 or 3 reagent RBCs phenotyped for multiple antigens
• Reagent RBC


  Type O cell with: C, c, D, E, Fya, Fyb, Jka, Jkb, K, k, Lea, Leb, P1, M, N, S and s antigens
• Antibody Screening


  • To detect as many clinically significant antibodies as possible
  • To detect as few clinically insignificant antibodies as possible
  • To complete the procedure in a timely manner
• Antibody Screening Procedure


  1. Incubate reagent red cells

  2. Wash 3x

  3. Add AHG reagent

  4. Immediate Spin phase (optional)

  5. 37°C phase

  6. AHG phase
• Antigram


  A positive test result (in any phase) indicates the need for antibody identification
• Antibody specificity should be suspected when all screen cells yielding a positive reaction react at the same phase(s) and strength
• Multiple antibodies are most likely present when screen cells react at different phases or strengths
• A positive autologous control or DAT with all screen cells yielding a positive reaction should be suspected when the autologous control or DAT is positive and all screen cells tested yield a positive reaction
• Common Blood Group Systems With Antibodies That Exhibit Dosage

  • Rh (except D)
  • Kidd
  • Duffy
  • MNSs
  • Lutheran
• Steps for Antibody Identification

  • Cross out panel cells with "O" reaction - do not cross out heterozygous antigens that show dosage
  • Look for matching pattern (cells with reaction)
  • Consider the antibody's usual temperature reactivity
• Possible Interpretations of Antibody Screening Results

  • Single alloantibody
  • Two alloantibodies, antigens only present on cell II
  • Multiple alloantibodies, warm and cold
  • Potent cold alloantibody binding complement in AGT
  • Multiple alloantibodies
  • Single alloantibody (dosage)
  • Probable IgG alloantibody
  • Single or multiple antibodies
  • Probably IgM alloantibody
  • Single warm alloantibody, antigen present on both cells
  • Antibody to high-prevalence antigen
  • Complement binding by a cold alloantibody not detected at IS
  • Warm alloantibodies
  • Transfusion reaction
  • Warm autoantibody
• Optimal Phase of Reactivity for Some Common Alloantibodies


  • Immediate Spin (Room Temperature): Lea, Leb
  • 37°C Incubation: M, N, Lua, P1
  • Antiglobulin Phase: Potent cold (IgM) antibodies (especially those causing hemolysis), Rh antibodies, Some warm antibodies, if high in titer (e.g., D, E, and K), Kell
• Antibody Identification


  Identification of an antibody to red cell antigen(s) requires testing the serum against a panel of selected red cell samples with known antigen composition
• Antibody Identification Panel


  A collection of group O reagent RBCs with diverse antigen expression
• Rule of Three


  Patient serum must be: Positive with cells with the antigen, Negative with cells without the antigen
• Additional Techniques for Resolving Antibody Identification: Selected Panel, Enzymes, Neutralization, Adsorption (Absorption), Antibody Titration
• Selected Panel


  The cells selected for testing should have minimal overlap in the antigens they possess
• +000 00+0+00+0 +0+ +0++0 +++00+0++00
• + + + 0 0 + 0 + +00
• + 0 + + +0+0
• + + 0 + + 0 0 + 0+0++0++0++0+0+0++
• 00 + + + 00+0+0+++0+00+0+0+0+ +00 2+
• Additional Techniques for Resolving

  Antibody Identification
• Additional Techniques


  • Selected Panel
  • Enzymes
  • Neutralization
  • Adsorption (Absorption)
  • Antibody Titration
• Initial Panel Results
• DCcEe CW Kk Kp Kpb Js Jsb Fy Fyb JK Jkb Le Leb P, M|NS s Luª Lub Xg" IS 37 AHG CC
• + +00+ + + +0+0+0++
• 0+ +0 +00
• Donor Cell number
• + + 0 0 0
• Selected Cell Panel
• DCcEe CW KkKpa Kpb JS Jsb Fya Fyb Jka Jk Lea Leb P, MN SS Lu Lub Xga IS 37 AHG CC
• o + + °
• + 0+ +
• + 0 + + + 0
• 0+0+ +0+0++00
• + 0 00 0 3+
• + +
• 00 2+