Temperature and the formation of radiation-induced chromosome aberrations. I. The effect of irradiation temperature.

Irradiation temperature, changed from 37 degrees C to 4 degrees C, acts as a dose-modifying factor with regard to the dose-yield relationship for dicentric chromosome aberrations in human lymphocytes irradiated with 150 kV X-rays. The temperature dependence of the aberration yield observed at constant dose is S-shaped, with a sharp rise near 15 degrees C from a lower plateau below 12 degrees C to a higher plateau beyond 17 degrees C. The aberration yield is determined by the irradiation temperature, irrespective of fast temperature changes from 4 degrees C to 37 degrees C or from 37 degrees C to 4 degrees C, applied at various delay times before and after irradiation. It is concluded that irradiation temperature influences the formation of chromatin lesions rather than their interaction.