DISCREPANCIES IN ABO GROUPING IN IMMUNOHEMATOLOGY.ppt

IT is about the discrepancies in ABO Grouping

1. ABO DISCREPANCIES

2. Common Sources of Technical Errors Resulting in ABO
Discrepancies
Inadequate identification of blood specimens,
test tubes, or slides
Too heavy or too diluted RCS
Clerical errors
Mix-up in samples
Missed observation of hemolysis
Failure to add reagents
Failure to follow manufacturer’s instructions
Uncalibrated centrifuge
Contaminated reagents
Warming during centrifugation

3. Group I Discrepancies
Between forward and reverse groupings because
of weakly reacting or missing antibodies
Newborns
Elderly patients
Patients w/ leukemia demonstrating
hypogammaglobulinemia
Patients w/ lymphomas demonstrating
hypogammaglobulinemia
Patients using immunosuppressive drugs that
yield hypogammaglobulinemia

4. Patients w/ congenital agammaglobulinemia
Patients with immunodeficiency diseases
Patients w/ bone marrow transplantations
(patients develop hypogammaglobulinemia
from therapy and start producing a different red
cell population from the transplanted bone
marrow)

5. Resolution:
Enhance the reaction in the reverse group
reaction by incubating the patient serum
w/ reagent A and B cells at room
temperature, 15-30 minutes
If there is still no reaction, incubate serum-
cell mixtures at 4 deg C for 15-30 mins.

6. Anti-AAnti-BAntiA,BA cellsB cells
Patientneg +++ ++++neg neg
Forward
Reaction
Reverse
Reaction

7. Rare Group I Discrepancy
Chimerism
True: twin
Artificial: blood transfusion of O to A or B
patient, transplanted bone marrows,
exchange transfusions, fetal-maternal
bleeding

8. Group II Discrepancies
Between forward and reverse groupings
because of weakly reacting or missing antigens
Subgroups of A and/or B
Leukemias and Hodgkin’s dse
Excess amounts of blood groups-specific soluble
substances(BGSS) present in the plasma in
association w/ CA of stomach and pancreas
“Acquired B” phenomenon associated w/
intestinal obstruction or malignancy
Antibodies to low incidence antigens in reagent
Anti-A or Anti-B

9. Example of Discrepancy Caused by an
Acquired B Antigen
Anti-AAnti-BAntiA,BA cellsB cells
Patient++++++ ++++neg ++++
Forward
Reaction
Reverse
Reaction

10. Anti-AAnti-BAntiA,BA cellsB cells
Patient+++++ ++++neg ++++
Forward
Reaction
Reverse
Reaction
Example of Discrepancy Caused by Low
Incidence Antibodies in the Reagent Antisera

11. Resolution:
Enhance the mixture by incubating it at
room temp for up to 30 minutes to
increase the association of antibody with
antigen. If negative, reduce the
temperature to 4 deg C.

12. Group III Discrepancies
Between forward and reverse groupings
caused by protein or plasma abnormalities
and result in rouleaux formation.
Elevated levels of globulin from certain
diseases
Elevated levels of fibrinogen
Wharton’s jelly
Plasma expanders, such as dextran and
polyvinyl-pyrrolidone (PVP)

13. Anti-AAnti-BAntiA,BA cellsB cells
Patient++++++ ++++++ ++++
Forward
Reaction
Reverse
Reaction
Example of Discrepancy Caused by Rouleaux
Formation

14. Resolution:
RCS and/or addition of saline

15. Group IV Discrepancies
Between forward and reverse groupings
owing to miscellaneous problems
Polyagglutination
Cold reactive antibodies
Warm autoantibodies
Unexpected ABO isoagglutinins
RBCs with cis”AB phenotype”

16. Resolution
Cold autoantibodies
Incubate patient’s red cells at 37 deg C,
then wash with saline 3x and retype.
If not successful, treat patient’s RBCs with
dithiothreitol (DTT) to disperse IgM-related
agglutination.
For serum, RBCs + serum/plasma can be
warmed to 37 deg C, re-test

17. Anti-AAnti-BAntiA,BA cellsB cells
Patient++ + ++++++++++++
Forward
Reaction
Reverse
Reaction

18. Anti-AAnti-BAntiA,BA cellsB cells
Patient++ +++++++++++++++

19. Anti-AAnti-BAntiA,BA cellsB cells
Patient+ + + ++++++++