Characterization of room temperature induced apoptosis in HL-60.

We found that exposure to room temperature (RT/21 degrees C) causes apoptosis in HL-60 cells. Here we characterized RT-induced apoptosis in HL-60. After exposure to RT, apoptosis starts within 6 h and more than 80% of the cells underwent apoptosis within 20 h. All cells, however, were committed to apoptosis after 16 h and no viable cells could be recovered. The caspase-1 inhibitor (YVAD-CHO) effectively blocked apoptosis, whereas the caspase-3 inhibitor (DEVD-CHO) did not. About 20% of newly obtained early passage HL-60 cells (passage 10) also underwent apoptosis by RT treatment. These data suggest that some population in HL-60 which responds to RT with apoptosis became dominant during passaging.