[Platelet immunoglobulins and complement in idiopathic thrombocytopenic purpura. Specificity to the IIb/IIIa membrane complex].

Platelet-associated IgG, IgM and C3c was studied by an enzyme-linked immunosorbent assay (ELISA) procedure using polystyrene microter plates and solubilize platelets. At the time of investigation patients fell into the following disease categories: 24 chronic ITP, 10 acute ITP and 11 ITP in remission (normal platelet counts). A significant elevation of platelet IgG was found in acute and chronic ITP. The C3c was increased in acute categories and normal in the others. There was not significant difference in the immunoglobulins and complement values between ITP in remission and normal donors. The platelet specificity of IgG and IgM antibodies to IIb/IIIa membrane complex was positive in 20% from chronic ITP and in none from acute. It is concluded that an elevated platelet immunoglobulins or complement is usefull for ITP diagnosis but the difference between acute and chronic categories only is possible in some cases by the antibodies specificity.