Immunohematology 3

Front 1

What is an ABO discrepancy?

Back 1

-ABO forward/ front type does not match ABO reverse/ back type
-Mixed-field agglutination

Front 2

Causes of ABO Discrepancies

Back 2

-Forward: Extra antigens, missing antigens and Mixed field agglutination
-Reverse: Extra antibodies, missing antibodies

Front 3

Missing Antigens (forward)

Back 3

ns

Front 4

Extra antigens (forward)

Back 4

ns

Front 5

Mixed-Field agglutination (forward)

Back 5

ns

Front 6

Extra Antibodies (reverse)

Back 6

ns

Front 7

Missing Antibodies (reverse)

Back 7

ns

Front 8

Why do we observe discrepancies in ABO Forward/ Front type?

Back 8

-Mixed Field agglutination
-Extra Antigens: B(A), Acquired B, Antibody Coated RBCs

Front 9

Why do we observe mixed-field agglutination?

Back 9

"Artificial" causes
-blood transfusion
-fetal/ maternal bleed
-hematopoietic progenitor cell transplant (HPC)

Front 10

A3 subgroup

Back 10

inherited mutation in A gene

Front 11

A3 subgroup

Back 11

-weaker than A2 with anti-A
-Characterized by mixed-field agglutination with Anti-A and Anti-A,B
-Serum occasionally contains anti-A1 (will make sometimes)

Front 12

Chimerism

Back 12

Fraternal twins
mosaicism from despermy

Front 13

How is mixed field agglutination characterized

Back 13

by small tightly agglutinated clumps of cells which chip off the buttom first followed by a stream of free cells giving a smoky looking background or vice versa

Front 14

Why is it important to recognize mixed field?

Back 14

-May provide unrecognized clinical information about patient
-May identify mistransfusion

Front 15

Why do we observe extra antigen?

Back 15

B(A)
Acquired B
Antibody coated RBCs

Front 16

Acquired B

Back 16

ns

Front 17

Acquired B

Back 17

-Found in A1 individuals
-Monoclonal anti-A most sensitive
-found in bacterial infection (deacetylase enzyme)

Front 18

Acquired B Antigen

Back 18

ns

Front 19

Antibody coated RBCs

Back 19

DAT positive RBCs may cause spontaneous agglutination

Front 20

Why do we observe missing antigen?

Back 20

-Subgroups of A/B
-mutations in A or B gene resulting in altered transferase which weakly puts stuff on.

Front 21

A2 phenotype

Back 21

Qualitative difference
A2 can make anti A1 why?
transferase activity differs, A1 transferase adds GalNAc to repetitive Type 3H and Type 4H

Front 22

Cold Autoantibody

Back 22

ns

Front 23

Cold-reactive Alloantibodies

Back 23

ns

Front 24

Rouleaux

Back 24

ns

Front 25

Missing Antibodies

Back 25

ns

Front 26

Missing Antibodies

Back 26

ns

Front 27

Resolving ABO Discrepancies

Back 27

1.Assume either forward or reverse type is correct
2.Assess if discrepancy in opposite typing is due to extra or missing antigens/antibodies
3.review patient history for clues to determining cause of discrepancy
4.perform testing to verify cause of discrepancy and interpret ABO

Front 28

Repeat ABO type-Why?

Back 28

many labs routinely repeat ABO (compare results)
mistakes happen

Front 29

patient transfused

Back 29

mixed field

Front 30

infused with ABO compatible plasma products

Back 30

extra antibody

Front 31

Received IVIG

Back 31

extra antibody

Front 32

6 months or younger

Back 32

missing antibody

Front 33

testing RBCs to resolve ABO discrepancies

Back 33

type with: Anti-A,B, Anti-A1 lectin, different manufacturer of Anti-A, -B, -AB, Acidified Anti-B, lectin Kit

Front 34

Testing RBCs to resolve ABO Discrepancies

Back 34

-incubate -A,-B,-A,B at Room temp
-treat to remove antibody
-look at RBCs in plasma to assess for rouleaux
-phenotype patient if alloantibody is identified

Front 35

Anti-A,B reagent

Back 35

polyclonal or monoclonal
FDA requirement-reacts with Ax RBCs

Front 36

-

Back 36

-

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-

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-

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-

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-

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