ELECTROPHORETIC PROPERTIES OF PLATELETS FROM NORMAL, THROMBOTIC AND ITP PATIENTS BY DOPPLER ELECTROPHORETIC LIGHT-SCATTERING ANALYSIS

At fixed pH and ionic environment platelet net charge depends on the c omposition of surface glycoproteins and phospholipids. It is believed that this composition changes, becoming more negative in the course of activation, and that certain thrombotic disorders such as transient i schemic attacks (TIA) may be associated with platelet activation. To i nvestigate this hypothesis we measured the electrophoretic mobility (U ) of normal platelets, activated normal platelets and platelets from p atients with TIA and immune thrombocytopenic purpura (ITP), Normal pla telets gave U = -0.91 +/- 0.05 mu m cm/vs, while normal platelets acti vated by ADP gave -1.25 and by collagen -1.70, TIA patients (n = 22) h ad mean U = -1.14 +/- 0.10 and the ITP patients (n = 37) had U = -1.07 +/- 0.13. The U of both patient groups differed significantly from no rmal controls, P < 0.001. Indeed, only 2 of the 22 TIA cases had U wit hin 2 SD of the control value. The ITP group included 10 patients with TIA-like symptoms; the mean U of this subgroup was identical to that of the TIA group without ITP. We conclude that U is a useful measure f or research on platelet abnormalities and may even be useful as a rout ine clinical tool. This work was greatly facilitated by the use of an automated instrument, the DELSA 440, allowing determination of U of a given sample in as little as 5 min.