Murine bone marrow-derived mast cells exhibit evidence of both apoptosis and oncosis after IL-3 deprivation

IL-3 deprivation has been reported to induce apoptosis of bone marrow-deriv ed mast cells. In order to evaluate this type of cell death further, we emp loyed trypan blue and propidium iodide stainings, photometric enzyme immuno assay, fluorescence measurement of caspase-3, DNA electrophoresis, flow cyt ometry and transmission electron microscopy. In this experiment, although s everal evidences supporting apoptosis were demonstrated some findings were not consistent with typical apoptosis. On the other hand, electron microsco pical observation demonstrated that most cells from all the time phases aft er IL-3 deprivation showed the morphology of typical oncosis, i.e. cell swe lling, disintegration of ultrastructure and subsequent karyolysis. Only a s mall number of cells from the later time phases showed apoptotic morphology . We here suggest that BMMCs undergo both apoptosis and oncosis after IL-3 deprivation and that the dominant type of prelethal change is oncosis in al l time phases, although apoptosis also plays a partial role in the late tim e phases.