Epitope mapping of ADAMTS13 autoantibodies in acquired thrombotic thrombocytopenic purpura.

Abstract

Severe deficiency of the von Willebrand factor (VWF)-cleaving protease ADAMTS13 can lead to thrombotic thrombocytopenic purpura (TTP), a disease associated with the widespread formation of platelet-rich thrombi in many organs. Autoantibodies that inactivate ADAMTS13 are the most frequent cause of acquired TTP. Little is known about epitope specificity and reactivity of anti-ADAMTS13 antibodies. In this study, a series of ADAMTS13 domains were expressed in Escherichia coli, and the reactivity of purified recombinant fragments with anti-ADAMTS13 auto-antibodies from 25 patients with severe ADAMTS13 deficiency was evaluated in vitro. All TTP plasmas contained antibodies directed against the cysteine-rich spacer (cys-rich/spacer) domain of ADAMTS13. In the plasma of 3 patients, antibodies were detected that reacted exclusively with the cys-rich/spacer domain, underscoring the importance of this region for functional activity of ADAMTS13. In 64% of the plasmas, antibodies reacted with the 2 CUB domains, and in 56% they reacted with the isolated first thrombospondin type 1 (TSP-1) repeat and with the compound fragment consisting of the catalytic, the disintegrin-like, and the TSP1-1 domain. Less frequently, in 28% of the plasmas, antibodies reacted with the TSP1 repeats 2 to 8. Unexpectedly, antibodies reacted with the propeptide region in 20% of the plasmas. In conclusion, this study shows that even though anti-ADAMTS13 autoantibodies react with multiple domains of the protease, the cys-rich/spacer domain is consistently involved in antibody reactivity.

• Authors: Christoph Klaus, Barbara Plaimauer, Jan-Dirk Studt, Friedrich Dorner, Bernhard Lämmle, Pier Mannuccio Mannucci, Friedrich Scheiflinger
• Journal: Blood (Blood) Vol. 103 Issue 12 Pg. 4514-9 (Jun 15 2004) ISSN: 0006-4971 [Print] United States
• PMID: 14976043 (Publication Type: Journal Article)

Chemical References

• Autoantibodies
• Epitopes
• Peptide Fragments
• Recombinant Proteins
• von Willebrand Factor
• ADAM Proteins
• Metalloendopeptidases
• ADAMTS13 Protein
• ADAMTS13 protein, human

Topics

• ADAM Proteins
• ADAMTS13 Protein
• Adult
• Autoantibodies (blood)
• Cloning, Molecular
• Epitopes (analysis)
• Escherichia coli
• Female
• Humans
• Male
• Metalloendopeptidases (chemistry, genetics, immunology)
• Middle Aged
• Peptide Fragments (chemistry, genetics)
• Peptide Mapping
• Purpura, Thrombocytopenic, Idiopathic (blood, immunology)
• Recombinant Proteins (immunology)
• von Willebrand Factor (immunology)