THROMBOCYTOPOIETIC PROPERTIES OF ONCOSTATIN-M

Oncostatin M (OM) is a 28-kD glycoprotein that exhibits a panoply of b iologic effects. Based on histologic observations of increased splenic megakaryocytes in nude mice implanted with an OM-secreting cell line, the thrombocytopoietic properties of OM in mice were investigated in culture and in vivo. Alone, OM did not induce megakaryocytic colony fo rmation, but in combination with murine interleukin-3 (IL-3), OM marke dly enhanced colony formation. The effects of OM on colony formation w ere similar to those of IL-6, OM alone augmented acetylcholinesterase in short-term marrow cultures. In normal mice, the administration of O M augmented platelet counts without increasing other circulating blood cell counts. The increment in counts exceeded that observed with IL-6 . The kinetics of the OM response suggested that maximal increases in platelets occurred 3 days after the cessation of OM administration, ir respective of the duration of administration. In irradiated mice, OM a dministration accelerated platelet recovery and prevented the decrease in red blood cells observed in irradiated control animals. The data s how that OM behaves as a megakaryocytic maturation factor in vitro and augments platelet production in vivo. Based on these animal data, OM may have potential clinical utility as a thrombocytopoietic agent. (C) 1995 by The American Society of Hematology.