Megakaryocytes and myelofibrosis in gray platelet syndrome.

Studies have been carried out with cultured human megakaryocytes derived from Gray Platelet Syndrome blood and have demonstrated that MK-DGF and MK-F4 are present in the early stages of megakaryocyte maturation (day 5-6) but disappear in the late phase (day 9-11). In Gray platelets total mitogenic activity, PDGF and PF4 amounts were reduced while beta TG and PF4 plasma levels were slightly increased. These findings indicate a possible relationship between the loss of alpha granule contents from the megakaryocytes in the marrow and the myelofibrosis found in Gray platelet disorder and possibly associated in other diseases with platelet or megakaryocyte abnormalities.