Thromb Haemost 2005; 93(02): 267-283
DOI: 10.1160/TH04-05-0301
Blood Coagulation, Fibrinolysis and Cellular Haemostasis
Schattauer GmbH

The spacer domain of ADAMTS13 contains a major binding site for antibodies in patients with thrombotic thrombocytopenic purpura

Brenda M. Luken
1   Department of Plasma Proteins, Sanquin Research at CLB, Amsterdam, The Netherlands
,
Ellen A.M. Turenhout
1   Department of Plasma Proteins, Sanquin Research at CLB, Amsterdam, The Netherlands
,
Janine J.J. Hulstein
2   Department of Haematology, University Medical Center Utrecht, Utrecht, The Netherlands
,
Jan A. Van Mourik
1   Department of Plasma Proteins, Sanquin Research at CLB, Amsterdam, The Netherlands
3   Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
,
Rob Fijnheer
2   Department of Haematology, University Medical Center Utrecht, Utrecht, The Netherlands
,
Jan Voorberg
1   Department of Plasma Proteins, Sanquin Research at CLB, Amsterdam, The Netherlands
› Institutsangaben

Financial support: Supported by grants 00.16/01.14 from the Landsteiner Foundation of Blood Transfusion Research (LSBR) and a grant from the Dutch Thrombosis Foundation (grant no. 2000/001).
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Publikationsverlauf

Received 14. Mai 2004

Accepted after resubmission 10. Januar 2004

Publikationsdatum:
11. Dezember 2017 (online)

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Summary

Thrombotic thrombocytopenic purpura (TTP) is a microangiopathy often associated with a severely decreased activity of ADAMTS13. In plasma of the majority of patients withTTP, antibodies are present that inhibit the vonWillebrand factor (VWF) processing activity of ADAMTS13.We describe a sensitive assay that monitors binding of recombinant ADAMTS13 to immobilized IgG derived from patient plasma. Analysis of fifteen patients with TTP and severely reduced ADAMTS13 activity revealed that in all patients antibodies directed toADAMTS13 were present. Levels of anti-ADAMTS13 antibodies varied considerably among patients, specific antibody levels in plasma range from less than 100 ng/ml to over 1 μg/ml. Longitudinal analysis in three patients revealed that anti-ADAMTS13 antibody levels declined with different kinetics. For further characterization of anti- ADAMTS13 antibodies, we prepared a series of recombinan fragments corresponding to the various ADAMTS13 domains. All seven TTP plasma samples tested, showed reactivity of antibodies towards a fragment consisting of the disintegrin/ TSR1/cysteine-rich/spacer domains. In one patient, we also observed reactivity towards the TSR2–8 repeats. No binding of antibodies to propeptide, metalloprotease and CUB domains was detected. To further delineate the binding site in the disintegrin/ TSR1/cysteine-rich/spacer region, we prepared additional ADAMTS13 fragments. Antibodies directed towards the cysteine- rich/spacer fragment were found in all plasma samples analyzed. No antibodies reacting with the disintegrin/TSR1 domains were detected. A recombinant fragment comprising the spacer domain was recognized by all patients samples analyzed, suggesting that the 130-amino-acid spacer domain harbors a major binding site for anti-ADAMTS-13 antibodies.