Thrombotic thrombocytopenic purpura (TTP)--an enigmatic disease finally resolved?

Thrombocytopenic thrombocytopenic purpura (TTP), characterized by hemolytic anemia, thrombocytopenia and fluctuating neurological abnormalities, was almost universally fatal until in the 1970s, when it was discovered that remissions could usually be achieved by exchanging plasma from patients with that of donors. For the following 25 years, this therapy was routinely used without any real understanding of why it was effective. Three recent papers published almost simultaneously offer insights into the molecular basis of TTP, a rationale for why plasma exchange is helpful, and avenues for development of new and highly specific therapeutic agents.