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Hemagglutination inhibition of Cromer blood group antibodies with soluble recombinant decay-accelerating factor
G L Daniels1, C A Green, R M Powell
1Bristol Institute for Transfusion Sciences, United Kingdom.
Insights
Soluble recombinant decay-accelerating factor (DAF) effectively identifies Cromer blood group system antibodies, aiding transfusion testing. Domain-deleted DAF precisely maps antibody epitopes, improving Cromer system antibody identification.
Area of Science:
- Immunology
- Blood group serology
Background:
- Cromer blood group antigens reside on decay-accelerating factor (DAF, CD55).
- DAF comprises four short consensus repeats (SCRs).
- Cromer system antibodies can pose clinical challenges in blood transfusions.
Purpose of the Study:
- To evaluate soluble recombinant DAF (srDAF) for identifying Cromer blood group system antibodies.
- To utilize domain-deleted srDAF for precise epitope mapping of DAF.
Main Methods:
- Expression of srDAF constructs (full-length or partial SCRs) in Pichia pastoris.
- Hemagglutination-inhibition assays using Cromer system antibodies and DAF-specific monoclonal antibodies.
- Testing with domain-deleted srDAF to pinpoint antibody binding sites.
Main Results:
- srDAF inhibited hemagglutination by all tested Cromer system alloantibodies.
- No inhibition was observed with antibodies to other blood group systems.
- Specific SCRs were identified as the location for key Cromer blood group antigens (UMC, Tca, TcaTcb, WESb, Dra, Cra).
Conclusions:
- Hemagglutination inhibition with srDAF is a valuable tool for recognizing Cromer blood group system antibodies.
- This method simplifies pretransfusion testing and enhances the precision of antibody identification.
- Domain-deleted srDAF offers an accessible approach to determining DAF epitope locations.
Background:
Cromer blood group antigens are located on decay-accelerating factor (DAF, CD55), which contains four short consensus repeats (SCRs). Cromer system antibodies may be of clinical significance in blood transfusion.
Study Design And Methods:
Soluble recombinant DAF (srDAF) constructs, consisting of all four SCRs or of only two SCRs, were expressed in the yeast Pichia pastoris. They are used in hemagglutination-inhibition tests with Cromer system antibodies and with DAF-specific monoclonal antibodies.
Results:
The srDAF inhibited hemagglutination by all Cromer system alloantibodies in undiluted serum. Antibodies to antigens of other blood group systems were not inhibited by the srDAF. Hemagglutination-inhibition tests with domain-deleted srDAF showed that UMC is on SCR-4 and confirmed that Tca, TcaTcb, and WESb are on SCR-1; Dra is on SCR-3; and Cra is on SCR-4.
Conclusions:
Hemagglutination inhibition with srDAF is useful in the recognition of antibodies that belong to the Cromer blood group system and facilitates pretransfusion testing. This use of domain-deleted srDAF provides an easy method of determining epitope location on DAF and is an aid to more precise identification of Cromer system antibodies.