Chinese hamster cells in suspension were exposed to 20 kHz ultrasound (US) at 54 W/cm2 and various temperatures between 2 and 44 degrees C. Activation energies were 2.6 and 24 kcal/mole below and above 35 degrees C, respectively. Procaine, a local anaesthetic drug known to increase membrane fluidity, enhanced cellular inactivation by US above 41 degrees C, increasing the activation energy to 62 kcal/mole. The inactivation of the bacterium Salmonella typhimurium by US was also dependent on the exposure temperature, with an activation energy of 2.9 kcal/mole between 2 and 44 degrees C. These data are most simply explained by the hypothesis that membranes are a major target for cellular inactivation by US and that the fluidity of the membranes is important in this respect.
K-562 human leukemia cells grown in the presence of specific goat anti- K-562 gamma globulin, F(ab)'2, Fab', or Fab showed a decrease in DNA and protein syntheses and a loss of cell viability within several hours. Eventually all cells died and lysed within 2–5 days. These events occurred in the absence of added effector cells or complement. The effect on the cell was not due to proteolytic or other external lytic activity generated at the cell surface, since 51Cr-labeled bystander cells or antibody-sensitized bystander cells (chicken erythrocytes or K-562 cells) were not lysed when added to cultures of K- 562 cells incubated with immune globulin. The anti-K-562 gamma globulin was not observed to patch or cap on K-562 cells, but the ability of bound immunoglobulin to fix complement decreased markedly (50% in 60 min), so that no complement-mediated cytolysis could be observed at 2 hr. However, the immunoglobulin, at least portions of it, reacted with fluorescein--labeled rabbit anti-goat gamma globulin for about 16 hr. 125I-labeled immune globulin appeared to be internalized and released into the medium as small degradation products. 125I-labeled Fab did not appear to be internalized, since it was released intact and more rapidly from cells than the intact globulin.
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