ANTIBODY IDENTIFICATION

Question 1

• Used to detect clinically significant
antibodies in allogeneic blood
donors and in patients as part of pretransfusion compatibility testing for whole blood, RBCS, and
granulocyte components.

Answer 1

ANTIBODY SCREEN

Question 2

AB IDENTIFICATION

• Used to detect _____ in allogeneic blood donors and in patients as part of _______testing for (3)

Answer 2

clinically significant antibodies

pretransfusion compatibility testing

whole blood,
RBCS, and
granulocyte components.

Question 3

• The *reagent red cells come with an_____ or _____ sheet.

Answer 3

antigram or antigen profile sheet.

Question 4

The______ shows the phenotype of each reagent cell used

Answer 4

antigram

Question 5

Purpose of Ab Screening

Answer 5

Antibody detection

Question 6

A positive antibody screen means that…

Answer 6

an unexpected antibody is present in the patient’s serum.

Question 7

If the antibody screen is positive, the antibody must be identified by performing an…

Answer 7

antibody panel.

Question 8

Immediate Spin phase (optional)
Centrifuge
Observe for hemolysis and agglutination

Components???

Answer 8

2 drops patient’s plasma + 1 drop screen cell reagent

Question 9

37°C phase
Centrifuge
Observe for hemolysis and agglutination

What to do???

Answer 9

Add enhancement reagent (optional)

Incubate at 37°C

If antibodies present, RBC sensitization occurs

Question 10

AHG phase

Wash_______
Unbound_____ removed

Add ______ reagent
Sensitized RBCs cross-linked by antibodies in AHG

Confirm negative reactions with____

Answer 10

3 to 4 times with normal saline

antibodies

2 drops AHG reagent

Coombs’ control cells

Question 11

ANTIBODY SCREEN

REAGENT
An antibody screen consists of___________ with known antigen phenotypes.

Answer 11

2 or 3 group O reagent red cells (2-5%)

Question 12

Immediate Spin (Room
Temperature)

Optimal Phase of Reactivity

Answer 12

Le^a
Le^b
M
N
Lu^a
P1

Question 13

37°C Incubation

Optimal Phase of Reactivity

Answer 13

Potent cold (IgM) antibodies (especially those causing hemolysis)

Some warm antibodies, if high in titer (e.g., D, E, and K)

Question 14

Antiglobulin Phase

Optimal Phase of Reactivity

Answer 14

Rh
Kell
Duffy
Lu^b
Ss
Kidd

Question 15

ANTIBODY SCREEN
INTERPRETATION

Cold-reacting (Room temperature or lower; Immediate spin reaction)

3 examples???

Answer 15

IgM class

• anti-N, anti-l, and anti-P1

Question 16

ANTIBODY SCREEN
INTERPRETATION
Warm-reacting (AHG phase)
Antibodies against.. (4)

Answer 16

IgG class

Rh
Kell
Kidd
Duffy
Ss antigens

Question 17

•Is the autologous control negative or positive?

Positive antibody screen + Negative autocontrol →

Answer 17

Alloantibody

Question 18

•Is the autologous control negative or positive?

• Positive antibody screen + Positive autocontrol:
• No recent transfusion →

Answer 18

Autoantibody or drug-induced

Question 19

•Is the autologous control negative or positive?

• Positive antibody screen + Positive autocontrol:

• Recent transfusion
→

Answer 19

Donor cells coated with alloantibodies
May appear mixed-field

Question 20

Did more than one screen cell sample react? If so, did they react at the same strength and phase(s)?

One cell →

Answer 20

May suggest single antibody

Question 21

Did more than one screen cell sample react? If so, did they react at the same strength and phase(s)?

Multiple cells, same phase/strength →

Answer 21

Single specificity

Question 22

Did more than one screen cell sample react? If so, did they react at the same strength and phase(s)?

• Multiple cells, different phases/strengths →

Answer 22

Multiple antibodies

Question 23

Did more than one screen cell sample react? If so, did they react at the same strength and phase(s)?

• All screen cells & autocontrol positive →

Answer 23

Suspect autoantibody

Question 24

Is hemolysis or mixed-field agglutination present?

• Hemolysis: Suggests antibodies like

Answer 24

anti-Lea
anti-Leb
anti-PP1Pk
anti-Vel

Question 25

Is hemolysis or mixed-field agglutination present? • Mixed-field agglutination: Seen with

Answer 25

anti-Sda Lutheran antibodies

Question 26

- Seen in multiple myeloma, dextran use

Answer 26

rouleaux present

Question 27

- Mimics agglutination but: • Appears like stacked coins microscopically • Disperses with saline • Doesn't persist in AHG phase (washed away)

Answer 27

rouleaux

Question 28

is the process of determining the specific antibody or antibodies present in a patient/donor's blood after a positive antibody screen.

Answer 28

Antibody identification

Question 29

A panel consists of____________ with known phenotypes.

Answer 29

10 to 20 group "O" reagent red cells

Question 30

Panel requires…. (18) phenotypes

Answer 30

D, C, E, c, e, M, N, S, s, P1, Lea, Leb, K, k, Fya, Fyb, Jka, and Jkb

Question 31

EXCLUSION/"RULE-OUTS"

Answer 31

• RBCs that gave a negative reaction in all phases of testing are examined • Only if there is homozygous expression of the antigen on the cell. Exceptions: low-prevalence antigens that are rarely expressed homozygously (ex. K, Kpª, Jsª, and Lua)

Question 32

Common Blood Group Systems With Antibodies That Exhibit Dosage

Answer 32

• Rh (except D) • Kidd • Dufty • MNSS • Lutheran

Question 33

• Variable antigen expression

Answer 33

(e.g., I, P1, Lea, Leb, Vel, Ch/Rg, Sda)

Question 34

Phase helps assess antibody type and clinical significance: • Immediate spin (IS): • 37°C phase: • AHG phase:

Answer 34

Often IgM (usually not clinically significant) Potent IgG antibodies may appear (e.g., anti-D, -E, -K) Detects most clinically significant IgG antibodies

Question 35

Reactions at different or multiple phases may suggest:

Answer 35

• Multiple antibodies • Dosage effect (homozygous cells reacting earlier)

Question 36

Is the autologous control positive or negative? • Autocontrol =

Answer 36

Patient/Donor serum tested against their own red cells

Question 37

• Negative autocontrol → • Positive autocontrol →

Answer 37

Suggests presence of an alloantibody Indicates possible autoantibody

Question 38

• Can mask underlying alloantibodies - Makes identification more complex

Answer 38

Positive autocontrol