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%

Ab screening Ab identification Compatibility Testing Ab screening Indirect Antiglobulin Test 2 or 3 red blood cells To detect ANY clinically significant Ab Ab identification 11 reagent panel cells To detect THE clinically significant Ab

Unexpected Antibodies (Non-A, Non-B) * Unexpected Antibodies (Non-A, Non-B) Found in: Chronically transfused patients Pregnancy Transplants Needle sticking

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

* 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.

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 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

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 * 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.

Antibody Identification

Antibody 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.

* 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.

Antibody Screening / Identification

Antibody Specificity (confirmation) * 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.

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.