Influenza A infection triggers thrombotic thrombocytopenic purpura by producing the anti-ADAMTS13 IgG inhibitor.

A 68-year-old Japanese woman infected with influenza A developed thrombotic thrombocytopenic purpura (TTP) 2 days after having a fever. Routine laboratory tests on admission suggested a diagnosis of disseminated intravascular coagulation. However, ADAMTS13 assays showed an extremely low level of plasma ADAMTS13 activity with a high titer of anti-ADAMTS13 inhibitor (IgG). Despite high-dose methylprednisolone therapy with daily plasma exchange for 3 consecutive days, the patient died of pulmonary congestion complicated by cardiac failure. Our experience here provides the first evidence that influenza A infection is sufficient to trigger TTP by producing the anti-ADAMTS13 IgG inhibitor.