Low temperature-induced cell surface membrane vesicle shedding is associated with DNA fragmentation

Abstract

Temperature shift conditions of 0 ° to 22 °C or 0 ° to 37 °C induce the formation and shedding of membrane vesicles (MV) from P815 tumor cell surfaces. When the MV shedding process takes place at 22 °C it occurs without changes in cell surface membrane permeability, whereas at 37 °C, changes in permeability to 51Cr and trypan blue do occur, thus mimicking the lymphocyte-mediated lytic process of tumor cells [1]. The present studies demonstrate that nuclear DNA fragmentation also occurs in both 0 ° to 22 °C and 0 ° to 37 °C temperature shifts but cell surface membrane permeability to DNA fragments occurs only in the latter condition, i.e., 0 ° to 37 °C. The microtubule-stabilizing agent deuterium oxide (D 2O) inhibited the MV shedding process, the changes in membrane permeability, and DNA fragmentation. When P815 cells which had been induced to shed MV by the 0 ° to 22 °C temperature shift were labeled with 51Cr and used as targets for alloimmune lymphocytes, they were found to be as susceptible to T-cell lysis as control P 815 cells. This result indicates that the lytic effect of alloimmune T lymphocytes can be exerted at the target cell surface membrane level independently of nuclear DNA fragmentation.