Platelets of normal persons were separated into five fractions by centrifugation in discontinuous Ficoll density gradients. Enzyme activities of lactic dehydrogenase, phosphoglycerate kinase, glyceraldehyde phosphate dehydrogenase, pyruvate kinase, glucose-6-phosphate dehydrogenase and content of protein were constantly higher in the heavy fraction IV compared with the light fraction I. With regard to the platelet volume, however, these differences were compensated almost completely.

Platelets of patients with thrombocytosis following splenectomy, in chronic granulocytic leukaemia and in polycythaemia vera were separated into five fractions by centrifugation in discontinuous Ficoll density gradient. Platelet volume, content of protein and enzyme activities of lactic dehydrogenase, phosphoglycerate kinase and glyceraldehyde phosphate dehydrogenase were distinctly higher for the three groups in the heavy fraction IV compared with the light fraction I. With regard to the platelet volume, however, these differences were compensated almost completely like in the normal persons.