Interleukin-6 and erythropoietin act as direct potentiators and inducers of in vitro cytoplasmic process formation on purified mouse megakaryocytes.

Mouse megakaryocytes were purified using a rabbit antimouse platelet serum, and magnetic beads were conjugated with an antirabbit IgG antibody. The purified cells were 95.8 +/- 1.2% megakaryocytes, and the recovery and viability of the megakaryocytes were 70 +/- 18.4%, and 80 +/- 13.4%, respectively. The effects of recombinant erythropoietin (Epo), interleukin-6 (IL-6), and IL-1 beta on these purified megakaryocytes were studied. Epo and IL-6 significantly increased DNA synthesis in these cells, but IL-1 beta did not. Similarly, both Epo and IL-6, but not IL-1 beta, increased the acetylcholinesterase (AchE) activity in the megakaryocytes. Epo and IL-6 stimulated the megakaryocytes to form cytoplasmic processes, which are considered to represent in vitro proplatelet formation. This process formation was inhibited by the addition of colchicine to the cultures. It was concluded that Epo and IL-6 are not only direct potentiators of megakaryocytes, but also inducers of in vitro cytoplasmic process formation on megakaryocytes.