Megakaryocytopoiesis Stimulating Factors are Highly Increased in Sera from Patients After Bone Marrow Transplantation

The relative roles of various humoral factors on megakaryocytopoiesis in man remain still unclear. However, in vivo and in vitro studies support a bi-level regulation of megakaryocyte formation. Hoffman et al. have observed, that sera from patients with hypomegakaryocytic thrombocytopenia significantly enhanced the formation of megakaryocytic progenitor cell (CFU-seg) derived colonies in an in vitro clonal assay suggesting a humoral feedback regulation acting in vivo. In order to investigate this feedback regulation after bone marrow transplantation (BMT), we tested sera from 2 patients with SAA, from 3 patients with CML and from one patient with AML in complete remission (CR), who underwent allogeneic BMT, for their capacity to stimulate megakaryocytic colonies from normal bone marrow a) before BMT, b) during severe aplasia following BMT, c) at the time of beginning engraftment, d) after haematological reconstitution.