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Transfusion. 2019 Jan 31. doi: 10.1111/trf.15147. [Epub ahead of print]

Development of a recombinant anti-Vel immunoglobulin M to identify Vel-negative donors.

Author information

1
Department of Hematopoiesis, Sanquin Research and Landsteiner Laboratory, AUMC, Amsterdam, The Netherlands.
2
Department of Experimental Immunohematology, Sanquin Research and Landsteiner Laboratory, AUMC, Amsterdam, The Netherlands.
3
Department of Immunohematology Diagnostic Services, Sanquin, Amsterdam, The Netherlands.
4
Department of Research and Lab Services, National Screening Laboratory Sanquin, Sanquin, Amsterdam, the Netherlands.

Abstract

BACKGROUND:

Alloimmunization against the high-frequency Vel blood group antigen may result in transfusion reactions or hemolytic disease of fetus and newborn. Patients with anti-Vel alloantibodies require Vel-negative blood but Vel-negative individuals are rare (1:4000). Identification of Vel-negative donors ensures availability of Vel-negative blood; however, accurate Vel blood group typing is difficult due to variable Vel antigen expression and limited availability of anti-Vel typing sera. We report the production of a recombinant anti-Vel that also identifies weak Vel expression.

STUDY DESIGN AND METHODS:

A recombinant anti-Vel monoclonal antibody was produced by cloning the variable regions from an anti-Vel-specific B cell isolated from an alloimmunized patient into a vector harboring the constant regions of immunoglobulin (Ig)G1-kappa or IgM-kappa. Antibody Vel specificity was tested by reactivity to SMIM1-transfected HEK293T cells and by testing various red blood cells (RBCs) of donors with normal, weak, or no Vel expression. High-throughput donor screening applicability was tested using an automated blood group analyzer.

RESULTS:

A Vel-specific IgM class antibody was produced. The antibody was able to distinguish between Vel-negative and very weak Vel antigen-expressing RBCs by direct agglutination and in high-throughput settings using a fully automated blood group analyzer and performed better than currently used human anti-Vel sera. High-throughput screening of 13,288 blood donations identified three new Vel-negative donors.

CONCLUSION:

We generated a directly agglutinating recombinant anti-Vel IgM, M3F5S-IgM, functional in manual, automated agglutination assays and flow cytometry settings. This IgM anti-Vel will improve diagnostics by facilitating the identification of Vel-negative blood donors.

PMID:
30702752
DOI:
10.1111/trf.15147

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