Platelet separation from the blood of severely thrombocytopaenic patients.

An efficient method is described for the isolation of platelets from the blood of severely thrombocytopaenic patients. The method, based on centrifugation over a density medium, was compared with platelet-rich plasma obtained by conventional differential centrifugation at a relative centrifugal force of 200 x g. With samples from thrombocytopaenic patients (n = 10, platelet counts between 7 and 22 x 10(9)/l), the density barrier method gave significantly improved platelet recoveries (82.1% +/- 6.2%) compared with differential centrifugation (61.6 +/- 4.6%) (P less than 0.001). Platelets isolated by the density barrier method showed no tendency to aggregate and were suitable for use in tests to detect platelet-associated immunoglobulin.