Autoimmunity in thrombotic thrombocytopenic purpura.

In the last few years, an autoimmune hypothesis for the pathogenesis of thrombotic thrombocytopenic purpura (TTP) has been proposed often, with variable success because of inconsistent supporting data. We are now aware that at least one subgroup of TTP patients does present with pathogenic autoantibodies (i.e, anti-ADAMTS13); this group consequently is a putative candidate for a curative treatment including plasma exchange (still the cornerstone of TTP treatment), together with corticosteroids or other immunosuppressants. Furthermore, for patients not responding to or relapsing following plasma exchange, the use of stronger immunosuppression (e.g., with the use of the anti-CD20 monoclonal antibody rituximab) should be considered as appropriate. Conversely, few data are actually available regarding the complex relationship between TTP and the antiphospholipid (aPL) syndrome, as well as other autoimmune diseases. Indeed, a correct differential diagnosis should be done on the basis of both different clinical presentations and autoantibody profile. At present, the presence of aPL antibodies should give evidence against a diagnosis of TTP, even though we cannot exclude that aPL antibodies may, in a minority of patients, be associated with a primary endothelial damage ultimately resulting in overt TTP.