Dielectric study of the programmed cell death, apoptosis, in human leukemia

Previous work in our laboratories showed that Broadband Dielectric Spectroscopy (DRS) reveals the very early physical events on damaged DNA which lead to the disruption of the DNA weak stacking forces. We followed up the evolution of this early physical damage into chemical damage within human cells. The induced chemical lesions result in biological effects including the initiation of programmed cell death, apoptosis, a mechanism resulting in extensive disruption of the external cell membranes. Using sensitive bio-methodologies we revealed that the early DNA damage was finally initiating apoptosis only when the damage was overwhelming intrinsic repair mechanisms. Finally, we were able to study the early stages of membrane alteration, associated with apoptosis, by measuring modifications in the dielectric properties of the cell membrane. It was found that in cells from donors with the chronic lymphocytic leukemia (CLL-cells), which exhibit a higher frequency of apoptosis, the values of the real and the imaginary part of the dielectric permittivity, e*, i.e. e' and e" respectively, and of the alternate field specific conductivity, s/sub ac/ as a function of frequency, were higher than those of the healthy donors, in which apoptosis occurs at very low frequency.