[Detection of platelet antibodies in idiopathic thrombopenic purpura]

The authors report the results of Dixon's assay modified by Follea in 24 cases of idiopathic thrombocytopenic purpura. The level of immunoglobulin G bound to platelet membrane was increased in 91 p. 100 of patients in the acute phase of the disease. An inverse correlation was demonstrated between platelet-bound antibody levels and platelet count as well as platelet survival. In all cases of refractory idiopathic thrombocytopenic purpura, the assay was positive and the mean level was higher. When the platelet count improved after prednisone therapy or after splenectomy, the level decreased. Platelet antibody determination seems to be useful for predicting the course of the disease. Patients with normal immunoglobulin G bound to platelet might have only C3, IgM or IgA. Dixon's assay is not specific to idiopathic thrombopenic purpura, since it is positive in other types of thrombocytopenia, but immunoglobulin G bound to platelet probably represents specific antiplatelet antibodies.