Effect of hypothermia and hyperthermia on the induction of chromosome aberrations by adriamycin in human leukocytes.

When human leukocytes are treated with adriamycin (ADR) for brief durations of 1 to 2 hr at concentrations ranging between 0.04 and 0.25 microgram/ml, a dramatic reduction is observed in the frequency of chromosome aberrations in cells treated at 4 degrees in comparison to those treated at 37 degrees. Conversely, a severalfold increase in the frequency of aberrations is found if temperature at the time of ADR treatment is raised to 43 degrees. At higher temperatures, the most dramatic increase is in the frequency of exchanges. These results point to a parallelism between these studies and those carried out previously for determining cell death with hyperthermia and ADR treatment. This effect on chromosome aberrations appears only if temperatures of 4 of 43 degrees are applied during the period of exposure of cells to ADR. No effect is evident if cells are posttreated at 4 or 43 degrees after ADR is removed from the medium. The question of true synergism versus "facilitation" of influx of ADR into cells is discussed in light of the information obtained by other workers on total quantities of the drug present in the cell.