Antibody Investigation
An antibody investigation is performed to identify or confirm the presence of clinically significant red cell antibodies. In general, clinically significant antibodies are antibodies known to have caused Hemolytic Disease of the Newborn (HDN), hemolytic transfusion reaction, or shortened survival of transfused red blood cells.
Transfused patients may experience potentially life-threatening hemolytic transfusion reactions if clinically significant red cell antibodies are misidentified or unidentified.
Antibody identification is part of a larger workflow that typically includes:
- ABO and Rh Typing of patient
- Antibody Screening to detect unexpected patient antibodies
- Antibody Identification of patient antibodies
- Antigen Typing of patient's pretransfusion specimen
- Antigen Typing of donor red cells if patient antibody is clinically significant
- Crossmatching with antigen-negative donor red cells
Pre-analytic
Before beginning to identify antibodies, available patient information must be reviewed. Many factors can provide valuable insights to help resolve the problem:
- patient history (transfusion history; obstetrical history; diagnosis)
- patient demographics
- sample characteristics
- initial serologic results and characteristics
Analytic
Each hospital determines the method of antibody identification but usually the same method used for antibody screening and compatibility testing is used for identification.
After the patient’s plasma (or serum) has been tested with the initial panel (using the method of choice) and results have been read and recorded, and assuming there is one or more positive reactions, the antibodies present are identified using a “cross-out” (“rule out”) method. The result is often identification of a probable antibody with several antibodies requiring further exclusion and therefore requiring additional tests to eliminate.
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Common Clinically Significant Antibodies
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Rh
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Kell
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Kidd
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Duffy
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MNSs
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anti-D
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anti-K
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anti- Jka
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anti-Fya
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anti-S
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anti-C
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anti- Jkb
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anti Fyb
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anti-s
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anti-E
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anti-c
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anti-e
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Post-analytic
To improve the quality of conclusions when identifying antibodies, a checklist is a simple tool to increase transfusion safety.
Additional considerations
Some patients form multiple antibodies or antibodies to high frequency antigens making compatible (antigen-negative) RBC difficult to find. In such cases, CBS may be able to help find antigen-negative donors through its database of rare donors or by mass phenotyping of donors.