Sandwich enzyme-linked immunosorbent assay was developed for evaluation of target antigens reacting with antiplatelet auto-and alloantibodies. The method based on specific immobilization of platelet antigens via monoclonal antibodies was applied to identify antigens of platelet-associated and serum autoantibodies in patients with different thrombocytopenias and to determine platelet HPA-1 alloantigens.

Antiplatelet antibodies were titered in children and adults with idiopathic thrombocytopenic purpura. The levels of platelet-associated IgG were elevated in 100% of the examined children and 86% of the adults, their mean titers being at least 10 times higher than in the control and differing little within the groups. Serum antibodies reacting with normal donor platelets were detected in 43% of adults and in only 18% of children. Improvement of the clinical picture and increase of the platelet count in these patients according to different protocols always correlated with a drop in the level of antiplatelet antibodies. The resuits point to the immune nature of idiopathic thrombocytopenic purpura in children.