ABO Discrepancies Flashcards
ABO discrepancies caused by diseases such as conditions caused by weaker reactions
Leukemia
Chromosome translocations
Hemolytic diseases
Hodgkin’s disease
Hypogammaglobulinemia (CLL)/Immunodeficiency
ABO discrepancies caused by diseases such as conditions that cause pseudoantigens
Acquired A:
• Proteus mirabilis
• Tn activation
Acquired B:
• E. coli 086
• Protreus vulgaris
• Intestinal obstruction
• Carcinoma of the colon & rectum
• C. tetani
Anti-A: 4+
Anti-B: 1+
A1 Cells: 0
B Cells: 4+
Probable group?
A
At what pH, acquired B cells will not react?
PH <6/7 (8.5)
Resolutions for acquire B
1) Acetic anhydride
2) monoclonal Anti-B
3) acidified Anti-B
4) secretor status
5) autocontrol
ABO discrepancies caused by technical errors
Incorrect specimen/labelling/recording of results
Failure to add reagents/sample
Over/undercentrifugation
Cell suspension too heavy or light
Contaminated reagents/materials
Mix-up of samples
Failure to follow manufacturer’s instructions
Uncalibrated centrifuge
Warming during centrifugation
ABO reaction denoting discrepancy
1+, 2+, w+
Problem of Group 1 discrepancies
Weakly reacting or missing Abs of reverse grouping
Causes of group 1 discrepancies
Newborns
Elderly patients
Hypogammaglobulinemia
• Leukemia (CLL)
• Malignant lymphoma
• Immunosuppressive drugs usage
• Bone marrow/stem cell transplantation
Agammaglobulinemia
• Congenital/acquired
• Immunodeficiency disease
Plasma/exchange transfusion
ABO subgroups
Resolution of group 1 discrepancies
1) incubate serum with reagent (RT, 15-30 min)
2) incubate (4oC, 15 min)
3) O cell control & autocontrol
4) age and patient history
Problem of group 2 discrepancies
Weakly reacting antigens of forward grouping
Causes of group 2 discrepancies
ABO subgroups
Weakened/depression of A/B antigens
• Leukemias
• Hodgkin’s disease
Pseudoantigens
Causes of group 2 discrepancies
ABO subgroups
Weakened/depression of A/B antigens
• Leukemias
• Hodgkin’s disease
Pseudoantigens
Resolutions of group 2 discrepancies
1) incubate RBCs with antisera (RT, 30 min)
2) incubate (4oC, 15-30 min)
3) O cell control & autocontrol
4) Enzyme treatment
Rare group 2 discrepancies
Blood group-specific soluble substances
Antibodies to low-incidence antigens in anti-A/anti-B
Chimerism (True/Artificial)
Resolution to BGSS
Washing patient cells with saline
Resolution of antibodies to low-incidence Ag to anti-A/anti-B
Repeat and use different lot number antisera
Monoclonal antibodies
Presence of two cell populations, recognised as self and individuals do not make anti-A/anti-B
True chimerism of twins
Two cell populations due to blood transfusions, bone marrow/stem cell transplantation, exchange transfusion, feto-maternal bleeding
Artificial chimerism
Problem of group 3 discrepancies
Plasma/protein abnormalities of forward/reverse typing caused by:
Elevated globulin levels
• multiple myeloma
• Waldenstrom’s macroglobulinemia
• plasma cell dyscrasia
• advanced cases of Hodgkin’s lymphoma
Elevated fribinogen levels
Plasma expanders
• dextran
• polyvinylpyrrolidone
Wharton’s jelly
Resolution of group 3 discrepancies
1) microscopic examination
2) saline-replacement techniques
3) wash cells with saline 3x (cord cells wash 6-8x)
4) run antibody screen
Problem of group 4 discrepancies
Miscellaneous problems of forward/reverse grouping caused by:
Cold reactive autoantibodies
Unexpected ABO isoagglutinins
Unexpected non-ABO alloantibodies
More than one ABO group RBCs
Polyagglutination
Resolution of group 4 discrepancies
Forward typing:
1) incubate RBCs (RT, wash with saline @ body temp 3x and retype
2) treat with 0.01 M dithiothreitol
Reverse typing:
1) rgt RBCs and serum warmed 37oC, mixed, tested and read @ 37oC
2) cold autoadsorption
Resolution of unexpected ABO isoagglutinin
determine specificity of antibody by pattern of reactivty (ex. test cells with anti-A lectin and serum with A1, A2, and O cells)
Resolution of unexpected non-ABO alloantibody
Run antibody screen and panel
Rare group 4 discrepancies
Antibody to acriflavin
Cis-AB phenotype
Resulotion of Antibody to Acriflavin
Wash RBCs with saline and retype
