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J Thromb Haemost. 2009 Mar;7(3):421-8. doi: 10.1111/j.1538-7836.2008.03250.x.

VH1-69 germline encoded antibodies directed towards ADAMTS13 in patients with acquired thrombotic thrombocytopenic purpura.

Author information

1
Department of Plasma Proteins, Sanquin-AMC Landsteiner Laboratory, Amsterdam, The Netherlands.

Abstract

BACKGROUND:

Autoantibodies directed towards ADAMTS13 are present in the majority of patients with acquired thrombotic thrombocytopenic purpura (TTP). Analysis of a set of antibodies derived from two patients with acquired TTP revealed frequent use of the VH1-69 heavy chain gene segment for the assembly of anti-ADAMTS13 antibodies.

OBJECTIVE:

We explored the ability of two VH1-69 germline gene-encoded antibodies to inhibit the von Willebrand factor (VWF)-processing activity of ADAMTS13 under different experimental conditions. Furthermore, the presence of VH1-69 encoded anti-ADAMTS13 antibodies in 40 patients with acquired TTP was monitored using monoclonal antibody G8, which specifically reacts with an idiotype expressed on VH1-69 encoded antibodies.

METHODS AND RESULTS:

Binding of the two VH1-69 encoded monoclonal antibodies was dependent on the presence of the spacer domain. Both antibodies inhibited ADAMTS13 activity under static conditions, as measured by cleavage of FRETS-VWF73 substrate and cleavage of VWF multimers. The recombinant antibodies were also capable of inhibiting the processing of UL-VWF strings on the surface of endothelial cells. G8-reactive antibodies directed towards ADAMTS13 were present in plasma of all patients containing anti ADAMTS13 antibodies.

CONCLUSIONS:

These results suggest that VH1-69 derived antibodies directed towards ADAMTS13 develop in the majority of patients with acquired TTP.

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