Complement-Mediated Autoimmune Thrombocytopenia

CHRONIC or adult autoimmune thrombocytopenia usually occurs with high levels of platelet-associated IgG antibodies,^{1 2 3} platelet-associated IgM antibodies,^{4 5 6} or both. The role of complement-mediated platelet injury in autoimmune thrombocytopenia has not been entirely explained. Most workers have found complement activation to be present,^{7 8 9 10 11 12 13 14} although some have not.^{15 16 17 18} Complement activation does have a leading role in certain types of immune thrombocytopenia, such as that due to drugs. In these disorders, severe thrombocytopenia results when complement activation is induced by a reaction of antibody with the drug (e.g., quinine) and platelet membranes.¹⁹ In this paper, we describe a patient with apparent chronic autoimmune . . .