Congress of the International Society on Thrombosis and Haemostasis

Adamts13 levels in HIV infected patients with and without TTP

Abstract number: PP-WE-726

Meiring¹ M., Van Staden¹ B., Van Hoorelbeke² K., Deckmyn² H., Badenhorst¹ P.

¹¹Haematology and Cell Biology, University of the Free State, Bloemfontein, South Africa ²²Laboratory for Thrombosis Research, KU Leven, campus Kortrijk, Kortrijk, Belgium

How-to-cite Meiring M, Van Staden B, Van Hoorelbeke K, Deckmyn H, Badenhorst P. Adamts13 levels in HIV infected patients with and without TTP. Journal of Thrombosis and Haemostasis 2009; Volume 7, Supplement 2: Abstract PP-WE-726

Thrombotic Thrombocytopenic Purpura (TTP) is a life-threatening disease characterised by microvascular platelet deposition and thrombus formation in selected organs. Typically a very rare disorder, TTP is being seen with increased frequency in patients infected with the human immunodeficiency virus (HIV). Deficiency of the Von Willebrand factor cleavage protease, also known as ADAMTS13, has been implicated as the cause of TTP. However, before studying the role of ADAMTS13 in HIV related TTP, it is necessary to know the normal values of ADAMTS13 levels in the population group in question. It is also necessary to know whether HIV infection in the absense of TTP has any effect on ADAMTS13 levels.

The aim of the stdy was threefold: a) to compare the ADAMTS13 levels in the local Caucasian and African populations; b) to study the effect of HIV infection on ADAMTS13 levels by correlating CD4 counts and viral loads with ADAMTS13 levels in HIV positive patients without TTP; and c) to measure ADAMTS13 levels in HIV infected patients with TTP.

An ELISA for ADAMTS13-antigen levels was standardised and optimised for routine use in our laboratory. Reference intervals were established for both local Caucasian (n = 19) and African (n = 21) populations. ADAMTS13 levels were measured in 36 HIV-positive patients without TTP and with CD4 counts varying from 4 to 681 and viral loads varying from 3400 to 700000. The CD4 counts were determined by flow cytometry and the viral loads with a RT-PCR kit. ADAMTS13 levels were also measured in 20 patiens with HIV associated TTP.

No statistically difference in ADAMTS13-antigen levels could be found in the local Caucasian and African population groups with reference ranges of 585–893 ng/mL and 620–808 ng/mL respectively. The ADAMTS13 levels were normal in the HIV patients without TTP (750 ± 89 ng/mL) and the severity of HIV infection as reflected by either CD4 count or viral load had no effect on the levels. ADAMTS13 levels in all 20 HIV associated TTP patients were low (244 ± 121 ng/mL).

Neither population group nor severity of HIV infection as reflected by CD4 count and viral load has any effect on ADAMTS13-antigen levels, making it a useful diagnostic tool in the setting of HIV positive patients with TTP.

Disclosure of interest: none declared.

To cite this abstract use the following format:

Journal of Thrombosis and Haemostasis 2007; Volume 5, Supplement 2: abstract number

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Date:	Unpresented
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Session name:	ISTH2009
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