Thromb Haemost 2019; 119(11): 1807-1815
DOI: 10.1055/s-0039-1696716
Cellular Haemostasis and Platelets
Georg Thieme Verlag KG Stuttgart · New York

Current Anti-HPA-1a Standard Antibodies React with the β3 Integrin Subunit but not with αIIbβ3 and αvβ3 Complexes

Behnaz Bayat
1  Institute for Clinical Immunology and Transfusion Medicine, Justus Liebig University Giessen, Giessen, Germany
,
Annalena Traum
1  Institute for Clinical Immunology and Transfusion Medicine, Justus Liebig University Giessen, Giessen, Germany
,
Heike Berghöfer
1  Institute for Clinical Immunology and Transfusion Medicine, Justus Liebig University Giessen, Giessen, Germany
,
Silke Werth
1  Institute for Clinical Immunology and Transfusion Medicine, Justus Liebig University Giessen, Giessen, Germany
,
Jieging Zhu
2  Blood Research Institute, Milwaukee, Wisconsin, United States
,
Gregor Bein
1  Institute for Clinical Immunology and Transfusion Medicine, Justus Liebig University Giessen, Giessen, Germany
,
Ulrich J. Sachs
1  Institute for Clinical Immunology and Transfusion Medicine, Justus Liebig University Giessen, Giessen, Germany
3  Center for Transfusion Medicine and Hemotherapy, University Hospital Marburg, Marburg, Germany
,
Sentot Santoso
1  Institute for Clinical Immunology and Transfusion Medicine, Justus Liebig University Giessen, Giessen, Germany
› Author Affiliations
Funding This work was supported by the German Society of Transfusion Medicine and Immunohematology (DGTI; to S.S.). J.Z. was supported by Grant HL131836 from the Heart, Lung, and Blood Institute of the National Institutes of Health.
Further Information

Publication History

26 March 2019

05 July 2019

Publication Date:
06 October 2019 (online)

Abstract

Background Fetal/neonatal alloimmune thrombocytopenia (FNAIT) results from maternal alloantibodies (abs) reacting with fetal platelets expressing paternal human platelet antigens (HPAs), mostly HPA-1a. Anti-HPA-1a abs, are the most frequent cause of severe thrombocytopenia and intracranial hemorrhage (ICH).

Objectives Titration of anti-HPA-1a in maternal serum using standard National Institute for Biological Standards and Control (NIBSC) 03/152 is one diagnostic approach to predict the severity of FNAIT. Recently, we found three anti-HPA-1a subtypes reacting with the β3 subunit independently or dependently from complexes with αIIb and αv. Endothelial cell-reactive anti-αvβ3 abs were found predominantly in cases with ICH. Our aim was to assess whether available standard material represents all anti-HPA-1a subtypes.

Materials and Methods In this study, anti-HPA-1a sera (NIBSC 03/152) and human monoclonal antibodies (moabs) against HPA-1a (moabs 26.4 and 813) were evaluated using transfected cell lines expressing αIIbβ3, αvβ3 or monomeric cβ3.

Results Flow cytometry analyses with well-characterized murine moabs recognizing αIIbβ3, αvβ3, or β3 alone demonstrated that AP3 reacts compound-independently, whereas compound-dependent moabs Gi5 and 23C6 reacted only with complexes. NIBSC 03/152, moabs 26.4, and 813 against HPA-1a reacted like AP3, same results were obtained with monomeric cβ3 in immunoblotting. Antigen capture assay targeting endothelial cells showed anti-HPA-1a reactivity disappearance after cβ3 beads adsorption. Furthermore, in contrast to anti-HPA-1a abs from ICH cases, none of NIBSC 03/152, 26.4, and 813 inhibited tube formation.

Conclusion These results suggest that current anti-HPA-1a standard material contains only the anti-β3 subtype. The absence of anti-αvβ3 makes NIBSC 03/152 less suitable as standard to predict the severity of FNAIT.

Authors' Contributions

B.B., G.B., S.S., and U.J.S. conceived and designed research. A.T., H.B., and S.W. performed experiments. B.B., U.J.S., and S.S. analyzed data. B.B. and S.S. wrote the manuscript. U.J.S. revised the manuscript.