39 Antibody Identification – LISS

Principle

The antibody identification test assists with the naming of unexpected blood group antibodies detected in the antibody screening procedure. The addition of a potentiating medium (LISS) helps promote the interaction of red cells allowing antibody/antigen reactions to occur quickly. The antigens present should explain positive reaction patterns seen on the panel red cells. These reactions are evaluated to identify the antibody(ies) present using an “exclusion” method. Antibody detection does not require enhancement media such as LISS; however, due to time limitations in student labs it is used.

Related Policies

This procedure applies to all patient or donor samples that require antibody identification.

Reagents

1. Antibody identification reagent red blood cell panel.
2. LISS
3. AHG (polyspecific or anti-IgG)
4. CCs
5. Isotonic saline

Procedure 

1. Label tubes with patient name and MRN or donor unit number and panel cell number identification.
2. Add two drops of patient serum to each test tube.
3. Add two drops of LISS to each tube and mix well.
4. Add one drop of thoroughly mixed panel cells to its respective tube.
5. Perform an auto if NOT performed with antibody screening test.
6. Incubate at 37°C for 10-15 minutes (as per manufacturer’s instructions).
7. Centrifuge the tubes for 20 seconds and examine for hemolysis.
8. Suspend and read for agglutination.
9. Grade and record test results (37°C) immediately while holding tube in hand. All positive and negative results should be carried on through to the end of the procedure.
10. Wash the tubes 4 times with isotonic saline. Decant completely and blot after the last wash.
11. Add 2 drops of AHG. Mix well and centrifuge for 20 seconds.
12. Suspend and read for agglutination. Grade and record test results immediately while holding tube in hand.
13. Control all negative antiglobulin tests by adding one drop of CC. Centrifuge for 20 seconds, re-suspend and read for agglutination.
14. Grade and record test results.

Interpretation

1. Agglutination/hemolysis in any phase of testing is a positive test result and indicates the presence of an antigen/antibody reaction. Hemolysis is a positive reaction when using a serum sample with polyspecific AHG.
2. No agglutination/hemolysis of the red cells is a negative test result and may indicate lack of an antigen/antibody reaction.

Notes

1. There must be agglutination in the last step with the IgG-sensitized red cells (CC) confirming the presence of active Antiglobulin reagent in the test mixture. If there is no agglutination or the results are indeterminate the test must be repeated . Record CC results as 1-4+.
2. If test results with all reagent red cells are reactive, consider the possibilities of an autoantibody, an antibody to high incidence antigen, or an antibody to red cell diluent.
3. Consider reactivity due to dosage effect prior to exclusion of the presence of an antibody.
4. Antibodies to low incidence antigens may be missed because of the absence of the antigen on the panel red cells.