Flow cytometric measurement of antiplatelet antibodies.

A flow cytometric technic was developed to detect platelet surface-bound immunoglobulin in patients with thrombocytopenia. Elevated platelet surface IgG and/or IgM was detected in 90.9% of patients with immune thrombocytopenia purpura (ITP). False positive results occurred in 9.3% of patients with nonimmune thrombocytopenia usually associated with sepsis. False negatives occurred most frequently in adults with chronic ITP. Measurement of platelet surface immunoglobulin with this flow cytometric technic helps differentiate immune from nonimmune thrombocytopenia.