Antibody Screening / Detection

& Antibody Identification

S. Nasizadeh, APCP

DiaMed Switzerland

“Direct Transfusion”

SHOT REPORT: IBCT Vs TTD

• ABO incompatibilities 9.5%• RhD incompatibilities 6.3%• Other blood group antigens 6.3%• TOTAL IBCT 22.1%

• HIV 0.17%• HBV 0.17%• HAV 0.17%• Malaria 0.17%• Bacterial contamination 0.51%• TOTAL TTDs 1.19%

Compatibility Testing

Ab screening

Indirect Antiglobulin Test

2 or 3 red blood cells

To detect ANY clinically significant Ab

Ab identification

Indirect Antiglobulin Test

11 reagent panel cells

To detect THE clinically significant Ab

Clinically Significant Antibodies

Rhesus (D, C, c, E, e)

Kel (K)

Kidd (Jka, Jkb)

Duffy (Fya, Fyb)

s

Anti-A & -B

Clinically Relatively SignificantAntibodies Lewis (Lea, Leb)

M

N

S

HI

Unexpected Antibodies (Non-A, Non-B)

Found in:

• Chronically transfused patients

• Pregnancy

• Transplants

• Needle sticking

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Clinically Significant Antibodies.

• Clinically significant antibodies in vitro are detected by the indirect antiglobulin technique (IAT) at a strict 37ºC.

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Antibody Screening

• The antibody screen is a

serological technique designed

to detect the presence of ANY

clinically significant

antibody(ies) present in

patient’s blood sample.

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Antibody Screening, Indications

For detection of irregular antibodies (non-ABO)

• Pre-transfusion tests

• Antenatal screening

• Donor units

• HDN

Antibody screening procedure

• Two cell pooled (only for donors)

• Two cells (not pooled)

• Three cells (recommended)

Antibody ScreeningAntibody Screening

Antibody Screening

• Allow the early detection of antibodies.

• Enable laboratories to phenotype available units, or obtain appropriate antigen negative blood from their Blood Centre.

• Negate the need for serological crossmatching if the screen is negative. C/T ratio = 2/1

VERY IMPORTANT

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Antibody Identification

• If the Antibody Screen is reactive, the

antibody specificity must be determined.

• So safe blood can be administered to the

Recipient.

• 11 reagent panel cells are to be used for

identification.

Antibody Identification

• The antibody identification is a

serological technique designed to

determine the TYPE of the

clinically significant antibody(ies)

present in patient’s blood sample.

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Antibody IdentificationAntibody Identification

Antibody Identification.

• When an antibody is detected in the antibody screen, crossmatch compatible blood should not be issued until:

– The antibody has been positively identified

and

– If the antibody is clinically significant, units

phenotyped and found antigen negative for the

appropriate antibody have been obtained.

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Antibody Exclusion

• Antibody exclusion is an important part of antibody investigative work and should always be performed.

• It is essential that when one antibody has been identified, the potential presence of another, masked, antibody has not been overlooked.

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Antibody Screening / Identification

Di aMed- I D Ant i gen - Tabl e Set I - I I 4515. 45. 01 Exp. dat e : 31. 05. 99

Rh- hr Kel l Duff y Ki dd Lewi s P MNS Lut h. Xg Speci al ag Resul t s

D C E c e Cw K k Kpa Kpb J sa J sb Fya Fyb J ka J kb Lea Leb P1 M N S s Lua Lub Xga AHG ENZ1 + + 0 0 + 0 0 + 0 + 0 + + 0 0 + + 0 + + + + + 0 + + - N/ T

2 + 0 + + 0 0 + + 0 + 0 + + + + 0 0 + 0 + 0 + 0 0 + 0 2+ N/ T

Di aMed- I D Ant i gen - Tabl e Set I D- Di aPanel 4517- 63- 01 Exp. dat e : 31. 05. 99

Rh- hr Kel l Duff y Ki dd Lewi s P MNS Lut h. Xg Speci al ag Resul t s D C E c e Cw K k Kpa Kpb J sa J sb Fya Fyb Jka J kb Lea Leb P1 M N S s Lua Lub Xga AHG ENZ

1 + + 0 0 + + + + 0 + 0 + + 0 0 + 0 + + + + + + 0 + + -

2 + + 0 0 + 0 0 + + + 0 + + + + 0 + 0 0 + + 0 + 0 + 0 2+s

3 + 0 + + 0 0 0 + 0 + 0 + 0 + 0 + 0 + + + 0 + 0 0 + + -

4 0 + 0 + + 0 + + 0 + 0 + + + + 0 0 0 + + + 0 + + + + 2+

5 0 0 + + + 0 0 + 0 + 0 + + 0 + + 0 + + + 0 + + 0 + 0 2+

6 0 0 0 + + 0 + + 0 + 0 + + 0 + + 0 + 0 0 + + + 0 + + 2+

7 0 0 0 + + 0 0 + 0 + 0 + 0 + 0 + + 0 0 0 + 0 + + + + -

8 + 0 0 + + 0 0 + 0 + + 0 0 0 + + 0 + + + + 0 + 0 + + 2+s

9 0 0 0 + + 0 0 + 0 + 0 + + + + + 0 + + + 0 + 0 0 + + 2+s

10 + + + 0 + 0 0 + 0 + 0 + 0 + + + + 0 0 0 + 0 + 0 + + 2+

11 + + + 0 0 0 0 + 0 + 0 + + + + + + 0 + + + 0 + 0 + + 2+

12 Aut ocont r ol 0

Antibody Specificity (confirmation)

• Current pre-transfusion guidelines state:

‘The specificity of the antibody should only be assigned when it is reactive with at least two examples of reagent red cells carrying the antigen and non-reactive with at least two examples of reagent red cells lacking the antigen’ .

• In order to meet this criteria, more than one identification panel may be necessary.

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Advatages of cross matching (XM)

• Easy,

• Routinely applied in all blood banks

• Relatively cheap

Disadvantages of cross matching

• Missing of some weak antibodies

• Compatible XM may still cause hemolytic reactions

• Time consuming in cases of incompatibility

Advantages of antibody screening

• Detection of weak antibodies (homozygous cells)

• Preparation and testing of blood at leisure• Batch and mass testing• Automation• Substitution of cross matching (in optimal

conditions)

Antibody screening

Requires :

- Training interpretation skills

- Time

- Tomans

Price / Time comparison

• XM

• RT + 37 AHG (2 tubes)--- 2x• Repeat incompatibles, e-g 4 units --- 8x

• 4 x 30 min= 120 min

• Ab Screen

• 2 x 37 C tubes (2x)

• Or 3 x 2 (AHG +ENZ)= 6x

• 30 min

Tests Are Performed to Provide Compatible Blood

With the Minimum Delay.

• The red cells will have the maximum survival following the transfusion.

• The donor’s blood will not cause an adverse reaction.

• Serological compatibility cannot guarantee that an antibody will not cause a transfusion reaction.

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