Complement-fixing platelet autoantibodies in autoimmune thrombocytopenia

A 16-year-old male patient is described with chronic autoimmune thrombocytopenic purpura and, after two years, "warm" autoimmune hemolytic anemia (Evans syndrome) who transiently developed complement-fixing platelet autoantibodies. The autoreactivity of these antibodies was established by quantitative complement fixation as well as by absorption and elution studies using autologous platelets. We believe this to be the first documented case with this very rare and peculiar type of platelet autoantibody.