blood bank lab exam

  1. Rh Typing reagents for Anti -D
    • saline (low protein)
    • high protein  
    • low protein 
    • monoclonal antibodies
  2. saline anti-D reagent
    • IgM
    • low protein based 
    • used to test for cells already coated with IgG antibody
    • disadvantage: cost, long incubation time, cannot test for weak D
  3. high protein anti-D reagent
    • faster
    • can weak D test
    • disadvantages: requires control tube, increased false positives
    • if control is positive, test is invalid
  4. monoclonal anti-D reagent
    • consists of a combination of various monoclonal anti-D reagents from different clones in order to ensure reactivity with a broad spectrum of Rh positive RBCs
    • can be used for slide, tube, microwell and automated testing
  5. Gel technology
    • pipette tip should not go past the gel
    • 0.8% cell suspension for forward typing
    • gel particles are composed of beads of dextran acrylamide
    • advantage: more sensitive and more standardized than tubing
    • disadvantage: cannot test hemolyzed samples. lipemic samples will clog the gel. Rouleux caused by high protein conct in serum with patients with multiple myeloma or waldenstrom's macroglobinemia
  6. why is there a mixed field in gel technology
    • recently transfused
    • bone marrow transplant
  7. Anti A reagent
    • monoclonal antibody
    • IgM
    • blue
    • Anti -A1 lectin: dolichos bilforus
  8. anti B reagent
    • monoclonal antibody
    • IgM
    • yellow
  9. RBC reagents for AB screen
    • group O
    • cells are suspended in 2 - 5% diluent
  10. Enhancement/Potentiators Reagents
    • 22% albumin
    • LISS (low ionic strength solution)
    • PEG (polyethylene Glycol
    • AHG
  11. 22% albumin
    • reduces zeta potential allowing RBCs to approach each other and increase chances of agglutination.
    • zeta potential: difference in electrical potential between RBC surface and outer layer of ionic cloud
  12. LISS (low ionic strength solution)
    lowers zeta potential and increases uptake of antibody onto RBC, thus reducing incubation time
  13. PEG (polyethylene glycol)
    • removes water from the test system, concentrating the antibodies present
    • thus increasing the degree of RBC sensitization.
    • more sensitive than LISS, albumin, saline.
    • do not use PEG with pt specimen with increased protein concentration such as multiple myeloma
  14. AHG reagents
    • allows for agglutination of incomplete antibodies
    • contains antibodies to both IgG and complement
  15. negative result for AHG
    must be controlled by adding Coombs control cells (check cells)
  16. check cells/ coombs control cells
    • They are Rh + coated with anti D
    • will react with anti IgG in the AHG reagent resulting in visible agglutination.
    • Addition of coombs control cells proves that AHG is working properly
    • must show a positive result to validate. if negative (no agglutination) the test must be repeated
  17. limitations from AB screening
    • cannot detect low titer antibodies
    • cannot detect low frequency antigens that are not present on any of the RBCs in the screen cell set
    • false negative reactions occur due to postzone when antigen is in excess
    • temperature and phase of reactivity
    • length of incubation
    • pH: antibodies react best at a neutral pH between 6.8 and 7.2
  18. what might give a positive DAT result
    • transfused within past 3 months
    • medications
    • autoimmune disorders
    • infections
  19. advantageous of molecular teting
    • ability to screen for multiple antigens at one time 
    • no interference from recent transfusion or positives DAT on RBCs
    • not limited due to lack of rare anti sera
    • able to screen large numbers of donors in a short time
  20. what are the techniques used when ABID panel does not have clear cut specificity
    • selected panel cells
    • enzymes
    • neutralization
    • adsorption
  21. selected panel cells
    • done after ABID
    • testing additional panels with minimal overlap in antigens they possess
  22. enzymes
    • treating panel cells with enzymes destroying certain antigens and enhancing expression of others
    • sulfyhydryl - DTT, 2-ME. destroys kell
    • ZZAP - denatures kell, MNS, Duffy
  23. autoadsorption
    • when autoantibodies are suspected, its best to use the patients own RBCs to adsorb the autoantibody.
    • autologous cells are first washed to remove unbound antibody
    • cells are incubated with patients serum. temperature is dependent on adsorbing either cold or warm antibody.
    • sample is inspected for signs of agglutination throughout incubation period. agglutination means that RBC binding sites are saturated with autoantibody.
    • serum is then harvested and incubated several times with new aliquots
    • if no agglutination is apparent during incubation the harvested serum is tested against patient's own RBCs
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blood bank lab exam
blood bank lab includes: ABO typing, Rh typing, Gel technique, ABID, Ab screening