Haematologica 2004;89: supplement no. 8 - Supplements ...

XVIII Congress of the Italian Society for Hemostasis and Thrombosis Research, Rome, Sept. 30-Oct. 3, 2004149against phospholipid-binding proteins and thromboticdiathesis. The most severe form of APS is CatastrophicAntiphospholipid Syndrome; (CAPS), a thromboticmicroangiopathy, clinically and histologicallysimilar to Thrombotic Thrombocytopenic Purpura(TTP). Most frequent form of TTP has an autoimmunepathogenesis, as it is due to the inhibition ofADAMTS13 by an IgG antibody. We studied 26patients suffering from APS in order to verify if alsoin these patients, like in TTP, there was a deficiency ofADAMTS13, due to the presence of autoantibodiesable to block the activity of ADAMTS13, possiblyexplaining their thrombosis. Patients’ plasma wastested for laboratory confirmation of antiphospholipidantibodies, activity of ADAMTS13, functionalVWF level (VWF:RCo) and VWF antigen (VWF:Ag).Plasma from 20 blood donors, matched for sex andage with patients, was used as control group. Resultsindicated that ADAMTS13, VWF:RCo, VWF:Ag were:98.6±14.6, 104.2±35.5 and 111.7±34.2, versus153.5±37.7, 187.7±72.4 and 194.3±64.2, respectivelyfor control and patient group (p